Running the annotated branch profiler on a box doing average work
(firefox, evolution, xchat, distcc farm), the likely() used in
grab_cache_page_write_begin() was incorrect most of the time:
correct incorrect % Function File Line
------- --------- - -------- ---- ----
1924262 71332401 97 grab_cache_page_write_begin filemap.c 2206
Adding a trace_printk() and running the function tracer limited to
just this function I can see:
gconfd-2-2696 [000] 4467.268935: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=7
gconfd-2-2696 [000] 4467.268946: grab_cache_page_write_begin <-ext3_write_begin
gconfd-2-2696 [000] 4467.268947: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=8
gconfd-2-2696 [000] 4467.268959: grab_cache_page_write_begin <-ext3_write_begin
gconfd-2-2696 [000] 4467.268960: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=9
gconfd-2-2696 [000] 4467.268972: grab_cache_page_write_begin <-ext3_write_begin
gconfd-2-2696 [000] 4467.268973: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=10
gconfd-2-2696 [000] 4467.268991: grab_cache_page_write_begin <-ext3_write_begin
gconfd-2-2696 [000] 4467.268992: grab_cache_page_write_begin: page= (null) mapping=ffff8800676a9460 index=11
gconfd-2-2696 [000] 4467.269005: grab_cache_page_write_begin <-ext3_write_begin
Which shows that a lot of calls from ext3_write_begin will result in the
page returned by "find_lock_page" will be NULL.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Temporary IO failures, eg. due to loss of both multipath paths, can
permanently leave the PageError bit set on a page, resulting in msync or
fsync returning -EIO over and over again, even if IO is now getting to the
disk correctly.
We already clear the AS_ENOSPC and AS_IO bits in mapping->flags in the
filemap_fdatawait_range function. Also clearing the PageError bit on the
page allows subsequent msync or fsync calls on this file to return without
an error, if the subsequent IO succeeds.
Unfortunately data written out in the msync or fsync call that returned
-EIO can still get lost, because the page dirty bit appears to not get
restored on IO error. However, the alternative could be potentially all
of memory filling up with uncleanable dirty pages, hanging the system, so
there is no nice choice here...
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Valerie Aurora <vaurora@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Testing ->mapping and ->index without a ref is not stable as the page
may have been reused at this point.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
NFS needs to be able to release objects that are stored in the page
cache once the page itself is no longer visible from the page cache.
This patch adds a callback to the address space operations that allows
filesystems to perform page cleanups once the page has been removed
from the page cache.
Original patch by: Linus Torvalds <torvalds@linux-foundation.org>
[trondmy: cover the cases of invalidate_inode_pages2() and
truncate_inode_pages()]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Salman Qazi describes the following radix-tree bug:
In the following case, we get can get a deadlock:
0. The radix tree contains two items, one has the index 0.
1. The reader (in this case find_get_pages) takes the rcu_read_lock.
2. The reader acquires slot(s) for item(s) including the index 0 item.
3. The non-zero index item is deleted, and as a consequence the other item is
moved to the root of the tree. The place where it used to be is queued for
deletion after the readers finish.
3b. The zero item is deleted, removing it from the direct slot, it remains in
the rcu-delayed indirect node.
4. The reader looks at the index 0 slot, and finds that the page has 0 ref
count
5. The reader looks at it again, hoping that the item will either be freed or
the ref count will increase. This never happens, as the slot it is looking
at will never be updated. Also, this slot can never be reclaimed because
the reader is holding rcu_read_lock and is in an infinite loop.
The fix is to re-use the same "indirect" pointer case that requires a slot
lookup retry into a general "retry the lookup" bit.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Reported-by: Salman Qazi <sqazi@google.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
70 hours into some stress tests of a 2.6.32-based enterprise kernel, we
ran into a NULL dereference in here:
int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
unsigned long from)
{
----> struct inode *inode = page->mapping->host;
It looks like page->mapping was the culprit. (xmon trace is below).
After closer examination, I realized that do_generic_file_read() does a
find_get_page(), and eventually locks the page before calling
block_is_partially_uptodate(). However, it doesn't revalidate the
page->mapping after the page is locked. So, there's a small window
between the find_get_page() and ->is_partially_uptodate() where the page
could get truncated and page->mapping cleared.
We _have_ a reference, so it can't get reclaimed, but it certainly
can be truncated.
I think the correct thing is to check page->mapping after the
trylock_page(), and jump out if it got truncated. This patch has been
running in the test environment for a month or so now, and we have not
seen this bug pop up again.
xmon info:
1f:mon> e
cpu 0x1f: Vector: 300 (Data Access) at [c0000002ae36f770]
pc: c0000000001e7a6c: .block_is_partially_uptodate+0xc/0x100
lr: c000000000142944: .generic_file_aio_read+0x1e4/0x770
sp: c0000002ae36f9f0
msr: 8000000000009032
dar: 0
dsisr: 40000000
current = 0xc000000378f99e30
paca = 0xc000000000f66300
pid = 21946, comm = bash
1f:mon> r
R00 = 0025c0500000006d R16 = 0000000000000000
R01 = c0000002ae36f9f0 R17 = c000000362cd3af0
R02 = c000000000e8cd80 R18 = ffffffffffffffff
R03 = c0000000031d0f88 R19 = 0000000000000001
R04 = c0000002ae36fa68 R20 = c0000003bb97b8a0
R05 = 0000000000000000 R21 = c0000002ae36fa68
R06 = 0000000000000000 R22 = 0000000000000000
R07 = 0000000000000001 R23 = c0000002ae36fbb0
R08 = 0000000000000002 R24 = 0000000000000000
R09 = 0000000000000000 R25 = c000000362cd3a80
R10 = 0000000000000000 R26 = 0000000000000002
R11 = c0000000001e7b60 R27 = 0000000000000000
R12 = 0000000042000484 R28 = 0000000000000001
R13 = c000000000f66300 R29 = c0000003bb97b9b8
R14 = 0000000000000001 R30 = c000000000e28a08
R15 = 000000000000ffff R31 = c0000000031d0f88
pc = c0000000001e7a6c .block_is_partially_uptodate+0xc/0x100
lr = c000000000142944 .generic_file_aio_read+0x1e4/0x770
msr = 8000000000009032 cr = 22000488
ctr = c0000000001e7a60 xer = 0000000020000000 trap = 300
dar = 0000000000000000 dsisr = 40000000
1f:mon> t
[link register ] c000000000142944 .generic_file_aio_read+0x1e4/0x770
[c0000002ae36f9f0] c000000000142a14 .generic_file_aio_read+0x2b4/0x770 (unreliable)
[c0000002ae36fb40] c0000000001b03e4 .do_sync_read+0xd4/0x160
[c0000002ae36fce0] c0000000001b153c .vfs_read+0xec/0x1f0
[c0000002ae36fd80] c0000000001b1768 .SyS_read+0x58/0xb0
[c0000002ae36fe30] c00000000000852c syscall_exit+0x0/0x40
--- Exception: c00 (System Call) at 00000080a840bc54
SP (fffca15df30) is in userspace
1f:mon> di c0000000001e7a6c
c0000000001e7a6c e9290000 ld r9,0(r9)
c0000000001e7a70 418200c0 beq c0000000001e7b30 # .block_is_partially_uptodate+0xd0/0x100
c0000000001e7a74 e9440008 ld r10,8(r4)
c0000000001e7a78 78a80020 clrldi r8,r5,32
c0000000001e7a7c 3c000001 lis r0,1
c0000000001e7a80 812900a8 lwz r9,168(r9)
c0000000001e7a84 39600001 li r11,1
c0000000001e7a88 7c080050 subf r0,r8,r0
c0000000001e7a8c 7f805040 cmplw cr7,r0,r10
c0000000001e7a90 7d6b4830 slw r11,r11,r9
c0000000001e7a94 796b0020 clrldi r11,r11,32
c0000000001e7a98 419d00a8 bgt cr7,c0000000001e7b40 # .block_is_partially_uptodate+0xe0/0x100
c0000000001e7a9c 7fa55840 cmpld cr7,r5,r11
c0000000001e7aa0 7d004214 add r8,r0,r8
c0000000001e7aa4 79080020 clrldi r8,r8,32
c0000000001e7aa8 419c0078 blt cr7,c0000000001e7b20 # .block_is_partially_uptodate+0xc0/0x100
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: <arunabal@in.ibm.com>
Cc: <sbest@us.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This slipped by when unifying the filemap and swap versions of
lock_page_or_retry()...
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
'end' shadows earlier one and is not necessary at all. Remove it and use
'pos' instead. This removes following sparse warnings:
mm/filemap.c:2180:24: warning: symbol 'end' shadows an earlier one
mm/filemap.c:2132:25: originally declared here
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This change reduces mmap_sem hold times that are caused by waiting for
disk transfers when accessing file mapped VMAs.
It introduces the VM_FAULT_ALLOW_RETRY flag, which indicates that the call
site wants mmap_sem to be released if blocking on a pending disk transfer.
In that case, filemap_fault() returns the VM_FAULT_RETRY status bit and
do_page_fault() will then re-acquire mmap_sem and retry the page fault.
It is expected that the retry will hit the same page which will now be
cached, and thus it will complete with a low mmap_sem hold time.
Tests:
- microbenchmark: thread A mmaps a large file and does random read accesses
to the mmaped area - achieves about 55 iterations/s. Thread B does
mmap/munmap in a loop at a separate location - achieves 55 iterations/s
before, 15000 iterations/s after.
- We are seeing related effects in some applications in house, which show
significant performance regressions when running without this change.
[akpm@linux-foundation.org: fix warning & crash]
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a single location where filemap_fault() locks the desired page.
There used to be two such places, depending if the initial find_get_page()
was successful or not.
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No real bugs, just some dead code and some fixups.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
mm: export generic_pipe_buf_*() to modules
fuse: support splice() reading from fuse device
fuse: allow splice to move pages
mm: export remove_from_page_cache() to modules
mm: export lru_cache_add_*() to modules
fuse: support splice() writing to fuse device
fuse: get page reference for readpages
fuse: use get_user_pages_fast()
fuse: remove unneeded variable
* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable: (27 commits)
Btrfs: add more error checking to btrfs_dirty_inode
Btrfs: allow unaligned DIO
Btrfs: drop verbose enospc printk
Btrfs: Fix block generation verification race
Btrfs: fix preallocation and nodatacow checks in O_DIRECT
Btrfs: avoid ENOSPC errors in btrfs_dirty_inode
Btrfs: move O_DIRECT space reservation to btrfs_direct_IO
Btrfs: rework O_DIRECT enospc handling
Btrfs: use async helpers for DIO write checksumming
Btrfs: don't walk around with task->state != TASK_RUNNING
Btrfs: do aio_write instead of write
Btrfs: add basic DIO read/write support
direct-io: do not merge logically non-contiguous requests
direct-io: add a hook for the fs to provide its own submit_bio function
fs: allow short direct-io reads to be completed via buffered IO
Btrfs: Metadata ENOSPC handling for balance
Btrfs: Pre-allocate space for data relocation
Btrfs: Metadata ENOSPC handling for tree log
Btrfs: Metadata reservation for orphan inodes
Btrfs: Introduce global metadata reservation
...
I/O errors can happen due to temporary failures, like multipath
errors or losing network contact with the iSCSI server. Because
of that, the VM will retry readpage on the page.
However, do_generic_file_read does not clear PG_error. This
causes the system to be unable to actually use the data in the
page cache page, even if the subsequent readpage completes
successfully!
The function filemap_fault has had a ClearPageError before
readpage forever. This patch simply adds the same to
do_generic_file_read.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Larry Woodman <lwoodman@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before applying this patch, cpuset updates task->mems_allowed and
mempolicy by setting all new bits in the nodemask first, and clearing all
old unallowed bits later. But in the way, the allocator may find that
there is no node to alloc memory.
The reason is that cpuset rebinds the task's mempolicy, it cleans the
nodes which the allocater can alloc pages on, for example:
(mpol: mempolicy)
task1 task1's mpol task2
alloc page 1
alloc on node0? NO 1
1 change mems from 1 to 0
1 rebind task1's mpol
0-1 set new bits
0 clear disallowed bits
alloc on node1? NO 0
...
can't alloc page
goto oom
This patch fixes this problem by expanding the nodes range first(set newly
allowed bits) and shrink it lazily(clear newly disallowed bits). So we
use a variable to tell the write-side task that read-side task is reading
nodemask, and the write-side task clears newly disallowed nodes after
read-side task ends the current memory allocation.
[akpm@linux-foundation.org: fix spello]
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Menage <menage@google.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Ravikiran Thirumalai <kiran@scalex86.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Shaohua Li reported parallel file copy on tmpfs can lead to OOM killer.
This is regression of caused by commit 9ff473b9a7 ("vmscan: evict
streaming IO first"). Wow, It is 2 years old patch!
Currently, tmpfs file cache is inserted active list at first. This means
that the insertion doesn't only increase numbers of pages in anon LRU, but
it also reduces anon scanning ratio. Therefore, vmscan will get totally
confused. It scans almost only file LRU even though the system has plenty
unused tmpfs pages.
Historically, lru_cache_add_active_anon() was used for two reasons.
1) Intend to priotize shmem page rather than regular file cache.
2) Intend to avoid reclaim priority inversion of used once pages.
But we've lost both motivation because (1) Now we have separate anon and
file LRU list. then, to insert active list doesn't help such priotize.
(2) In past, one pte access bit will cause page activation. then to
insert inactive list with pte access bit mean higher priority than to
insert active list. Its priority inversion may lead to uninteded lru
chun. but it was already solved by commit 645747462 (vmscan: detect
mapped file pages used only once). (Thanks Hannes, you are great!)
Thus, now we can use lru_cache_add_anon() instead.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is similar to what already happens in the write case. If we have a short
read while doing O_DIRECT, instead of just returning, fallthrough and try to
read the rest via buffered IO. BTRFS needs this because if we encounter a
compressed or inline extent during DIO, we need to fallback on buffered. If the
extent is compressed we need to read the entire thing into memory and
de-compress it into the users pages. I have tested this with fsx and everything
works great. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Make sure compiler won't do weird things with limits. E.g. fetching them
twice may return 2 different values after writable limits are implemented.
I.e. either use rlimit helpers added in
3e10e716ab ("resource: add helpers for
fetching rlimits") or ACCESS_ONCE if not applicable.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No one is calling this anymore as everyone has switched to
invalidate_mapping_pages long time ago. Also update a few
references to it in comments. nfs has two more, but I can't
easily figure what they are actually referring to, so I left
them as-is.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The cache alias problem will happen if the changes of user shared mapping
is not flushed before copying, then user and kernel mapping may be mapped
into two different cache line, it is impossible to guarantee the coherence
after iov_iter_copy_from_user_atomic. So the right steps should be:
flush_dcache_page(page);
kmap_atomic(page);
write to page;
kunmap_atomic(page);
flush_dcache_page(page);
More precisely, we might create two new APIs flush_dcache_user_page and
flush_dcache_kern_page to replace the two flush_dcache_page accordingly.
Here is a snippet tested on omap2430 with VIPT cache, and I think it is
not ARM-specific:
int val = 0x11111111;
fd = open("abc", O_RDWR);
addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
*(addr+0) = 0x44444444;
tmp = *(addr+0);
*(addr+1) = 0x77777777;
write(fd, &val, sizeof(int));
close(fd);
The results are not always 0x11111111 0x77777777 at the beginning as expected. Sometimes we see 0x44444444 0x77777777.
Signed-off-by: Anfei <anfei.zhou@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <linux-arch@vger.kernel.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's a simplified 'read_cache_page()' which takes a page allocation
flag, so that different paths can control how aggressive the memory
allocations are that populate a address space.
In particular, the intel GPU object mapping code wants to be able to do
a certain amount of own internal memory management by automatically
shrinking the address space when memory starts getting tight. This
allows it to dynamically use different memory allocation policies on a
per-allocation basis, rather than depend on the (static) address space
gfp policy.
The actual new function is a one-liner, but re-organizing the helper
functions to the point where you can do this with a single line of code
is what most of the patch is all about.
Tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the case of direct I/O falling back to buffered I/O we sync data
twice currently: once at the end of generic_file_buffered_write using
filemap_write_and_wait_range and once a little later in
__generic_file_aio_write using do_sync_mapping_range with all flags set.
The wait before write of the do_sync_mapping_range call does not make
any sense, so just keep the filemap_write_and_wait_range call and move
it to the right spot.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All callers really want the more logical filemap_fdatawait_range interface,
so convert them to use it and merge wait_on_page_writeback_range into
filemap_fdatawait_range.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
* mark struct vm_area_struct::vm_ops as const
* mark vm_ops in AGP code
But leave TTM code alone, something is fishy there with global vm_ops
being used.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
truncate: use new helpers
truncate: new helpers
fs: fix overflow in sys_mount() for in-kernel calls
fs: Make unload_nls() NULL pointer safe
freeze_bdev: grab active reference to frozen superblocks
freeze_bdev: kill bd_mount_sem
exofs: remove BKL from super operations
fs/romfs: correct error-handling code
vfs: seq_file: add helpers for data filling
vfs: remove redundant position check in do_sendfile
vfs: change sb->s_maxbytes to a loff_t
vfs: explicitly cast s_maxbytes in fiemap_check_ranges
libfs: return error code on failed attr set
seq_file: return a negative error code when seq_path_root() fails.
vfs: optimize touch_time() too
vfs: optimization for touch_atime()
vfs: split generic_forget_inode() so that hugetlbfs does not have to copy it
fs/inode.c: add dev-id and inode number for debugging in init_special_inode()
libfs: make simple_read_from_buffer conventional
* 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6: (21 commits)
HWPOISON: Enable error_remove_page on btrfs
HWPOISON: Add simple debugfs interface to inject hwpoison on arbitary PFNs
HWPOISON: Add madvise() based injector for hardware poisoned pages v4
HWPOISON: Enable error_remove_page for NFS
HWPOISON: Enable .remove_error_page for migration aware file systems
HWPOISON: The high level memory error handler in the VM v7
HWPOISON: Add PR_MCE_KILL prctl to control early kill behaviour per process
HWPOISON: shmem: call set_page_dirty() with locked page
HWPOISON: Define a new error_remove_page address space op for async truncation
HWPOISON: Add invalidate_inode_page
HWPOISON: Refactor truncate to allow direct truncating of page v2
HWPOISON: check and isolate corrupted free pages v2
HWPOISON: Handle hardware poisoned pages in try_to_unmap
HWPOISON: Use bitmask/action code for try_to_unmap behaviour
HWPOISON: x86: Add VM_FAULT_HWPOISON handling to x86 page fault handler v2
HWPOISON: Add poison check to page fault handling
HWPOISON: Add basic support for poisoned pages in fault handler v3
HWPOISON: Add new SIGBUS error codes for hardware poison signals
HWPOISON: Add support for poison swap entries v2
HWPOISON: Export some rmap vma locking to outside world
...
Introduce new truncate helpers truncate_pagecache and inode_newsize_ok.
vmtruncate is also consolidated from mm/memory.c and mm/nommu.c and
into mm/truncate.c.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Recently we encountered OOM problems due to memory use of the GEM cache.
Generally a large amuont of Shmem/Tmpfs pages tend to create a memory
shortage problem.
We often use the following calculation to determine the amount of shmem
pages:
shmem = NR_ACTIVE_ANON + NR_INACTIVE_ANON - NR_ANON_PAGES
however the expression does not consider isolated and mlocked pages.
This patch adds explicit accounting for pages used by shmem and tmpfs.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add the high level memory handler that poisons pages
that got corrupted by hardware (typically by a two bit flip in a DIMM
or a cache) on the Linux level. The goal is to prevent everyone
from accessing these pages in the future.
This done at the VM level by marking a page hwpoisoned
and doing the appropriate action based on the type of page
it is.
The code that does this is portable and lives in mm/memory-failure.c
To quote the overview comment:
High level machine check handler. Handles pages reported by the
hardware as being corrupted usually due to a 2bit ECC memory or cache
failure.
This focuses on pages detected as corrupted in the background.
When the current CPU tries to consume corruption the currently
running process can just be killed directly instead. This implies
that if the error cannot be handled for some reason it's safe to
just ignore it because no corruption has been consumed yet. Instead
when that happens another machine check will happen.
Handles page cache pages in various states. The tricky part
here is that we can access any page asynchronous to other VM
users, because memory failures could happen anytime and anywhere,
possibly violating some of their assumptions. This is why this code
has to be extremely careful. Generally it tries to use normal locking
rules, as in get the standard locks, even if that means the
error handling takes potentially a long time.
Some of the operations here are somewhat inefficient and have non
linear algorithmic complexity, because the data structures have not
been optimized for this case. This is in particular the case
for the mapping from a vma to a process. Since this case is expected
to be rare we hope we can get away with this.
There are in principle two strategies to kill processes on poison:
- just unmap the data and wait for an actual reference before
killing
- kill as soon as corruption is detected.
Both have advantages and disadvantages and should be used
in different situations. Right now both are implemented and can
be switched with a new sysctl vm.memory_failure_early_kill
The default is early kill.
The patch does some rmap data structure walking on its own to collect
processes to kill. This is unusual because normally all rmap data structure
knowledge is in rmap.c only. I put it here for now to keep
everything together and rmap knowledge has been seeping out anyways
Includes contributions from Johannes Weiner, Chris Mason, Fengguang Wu,
Nick Piggin (who did a lot of great work) and others.
Cc: npiggin@suse.de
Cc: riel@redhat.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Introduce new function for generic inode syncing (vfs_fsync_range) and use
it from fsync() path. Introduce also new helper for syncing after a sync
write (generic_write_sync) using the generic function.
Use these new helpers for syncing from generic VFS functions. This makes
O_SYNC writes to block devices acquire i_mutex for syncing. If we really
care about this, we can make block_fsync() drop the i_mutex and reacquire
it before it returns.
CC: Evgeniy Polyakov <zbr@ioremap.net>
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
generic_file_aio_write_nolock() is now used only by block devices and raw
character device. Filesystems should use __generic_file_aio_write() in case
generic_file_aio_write() doesn't suit them. So rename the function to
blkdev_aio_write() and move it to fs/blockdev.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
generic_file_direct_write() and generic_file_buffered_write() called
generic_osync_inode() if it was called on O_SYNC file or IS_SYNC inode. But
this is superfluous since generic_file_aio_write() does the syncing as well.
Also XFS and OCFS2 which call these functions directly handle syncing
themselves. So let's have a single place where syncing happens:
generic_file_aio_write().
We slightly change the behavior by syncing only the range of file to which the
write happened for buffered writes but that should be all that is required.
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
Signed-off-by: Jan Kara <jack@suse.cz>
Rename __generic_file_aio_write_nolock() to __generic_file_aio_write(), add
comments to write helpers explaining how they should be used and export
__generic_file_aio_write() since it will be used by some filesystems.
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
This simple helper saves some filesystems conversion from byte offset
to page numbers and also makes the fdata* interface more complete.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
In testing a backport of the write_begin/write_end AOPs, a 10% re-read
regression was noticed when running iozone. This regression was
introduced because the old AOPs would always do a mark_page_accessed(page)
after the commit_write, but when the new AOPs where introduced, the only
place this was kept was in pagecache_write_end().
This patch does the same thing in the generic case as what is done in
pagecache_write_end(), which is just to mark the page accessed before we
do write_end().
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Callers of alloc_pages_node() can optionally specify -1 as a node to mean
"allocate from the current node". However, a number of the callers in
fast paths know for a fact their node is valid. To avoid a comparison and
branch, this patch adds alloc_pages_exact_node() that only checks the nid
with VM_BUG_ON(). Callers that know their node is valid are then
converted.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Paul Mundt <lethal@linux-sh.org> [for the SLOB NUMA bits]
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we do readahead for sequential mmap reads, here is a simple
evaluation of the impacts, and one further optimization.
It's an NFS-root debian desktop system, readahead size = 60 pages.
The numbers are grabbed after a fresh boot into console.
approach pgmajfault RA miss ratio mmap IO count avg IO size(pages)
A 383 31.6% 383 11
B 225 32.4% 390 11
C 224 32.6% 307 13
case A: mmap sync/async readahead disabled
case B: mmap sync/async readahead enabled, with enforced full async readahead size
case C: mmap sync/async readahead enabled, with enforced full sync/async readahead size
or:
A = vanilla 2.6.30-rc1
B = A plus mmap readahead
C = B plus this patch
The numbers show that
- there are good possibilities for random mmap reads to trigger readahead
- 'pgmajfault' is reduced by 1/3, due to the _async_ nature of readahead
- case C can further reduce IO count by 1/4
- readahead miss ratios are not quite affected
The theory is
- readahead is _good_ for clustered random reads, and can perform
_better_ than readaround because they could be _async_.
- async readahead size is guaranteed to be larger than readaround
size, and they are _async_, hence will mostly behave better
However for B
- sync readahead size could be smaller than readaround size, hence may
make things worse by produce more smaller IOs
which will be fixed by this patch.
Final conclusion:
- mmap readahead reduced major faults by 1/3 and no obvious overheads;
- mmap io can be further reduced by 1/4 with this patch.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mmap read-around now shares the same code style and data structure with
readahead code.
This also removes do_page_cache_readahead(). Its last user, mmap
read-around, has been changed to call ra_submit().
The no-readahead-if-congested logic is dumped by the way. Users will be
pretty sensitive about the slow loading of executables. So it's
unfavorable to disabled mmap read-around on a congested queue.
[akpm@linux-foundation.org: coding-style fixes]
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need this in one particular case and two more general ones.
Now we do async readahead for sequential mmap reads, and do it with the
help of PG_readahead. For normal reads, PG_readahead is the sufficient
condition to do a sequential readahead. But unfortunately, for mmap
reads, there is a tiny nuisance:
[11736.998347] readahead-init0(process: sh/23926, file: sda1/w3m, offset=0:4503599627370495, ra=0+4-3) = 4
[11737.014985] readahead-around(process: w3m/23926, file: sda1/w3m, offset=0:0, ra=290+32-0) = 17
[11737.019488] readahead-around(process: w3m/23926, file: sda1/w3m, offset=0:0, ra=118+32-0) = 32
[11737.024921] readahead-interleaved(process: w3m/23926, file: sda1/w3m, offset=0:2, ra=4+6-6) = 6
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~
An unfavorably small readahead. The original dumb read-around size could
be more efficient.
That happened because ld-linux.so does a read(832) in L1 before mmap(),
which triggers a 4-page readahead, with the second page tagged
PG_readahead.
L0: open("/lib/libc.so.6", O_RDONLY) = 3
L1: read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\342"..., 832) = 832
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
L2: fstat(3, {st_mode=S_IFREG|0755, st_size=1420624, ...}) = 0
L3: mmap(NULL, 3527256, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fac6e51d000
L4: mprotect(0x7fac6e671000, 2097152, PROT_NONE) = 0
L5: mmap(0x7fac6e871000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x154000) = 0x7fac6e871000
L6: mmap(0x7fac6e876000, 16984, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fac6e876000
L7: close(3) = 0
In general, the PG_readahead flag will also be hit in cases
- sequential reads
- clustered random reads
A full readahead size is desirable in both cases.
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Auto-detect sequential mmap reads and do readahead for them.
The sequential mmap readahead will be triggered when
- sync readahead: it's a major fault and (prev_offset == offset-1);
- async readahead: minor fault on PG_readahead page with valid readahead state.
The benefits of doing readahead instead of read-around:
- less I/O wait thanks to async readahead
- double real I/O size and no more cache hits
The single stream case is improved a little.
For 100,000 sequential mmap reads:
user system cpu total
(1-1) plain -mm, 128KB readaround: 3.224 2.554 48.40% 11.838
(1-2) plain -mm, 256KB readaround: 3.170 2.392 46.20% 11.976
(2) patched -mm, 128KB readahead: 3.117 2.448 47.33% 11.607
The patched (2) has smallest total time, since it has no cache hit overheads
and less I/O block time(thanks to async readahead). Here the I/O size
makes no much difference, since there's only one single stream.
Note that (1-1)'s real I/O size is 64KB and (1-2)'s real I/O size is 128KB,
since the half of the read-around pages will be readahead cache hits.
This is going to make _real_ differences for _concurrent_ IO streams.
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This shouldn't really change behavior all that much, but the single rather
complex function with read-ahead inside a loop etc is broken up into more
manageable pieces.
The behaviour is also less subtle, with the read-ahead being done up-front
rather than inside some subtle loop and thus avoiding the now unnecessary
extra state variables (ie "did_readaround" is gone).
Fengguang: the code split in fact fixed a bug reported by Pavel Levshin:
the PGMAJFAULT accounting used to be bypassed when MADV_RANDOM is set, in
which case the original code will directly jump to no_cached_page reading.
Cc: Pavel Levshin <lpk@581.spb.su>
Cc: <wli@movementarian.org>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mapping->tree_lock can be acquired from interrupt context. Then,
following dead lock can occur.
Assume "A" as a page.
CPU0:
lock_page_cgroup(A)
interrupted
-> take mapping->tree_lock.
CPU1:
take mapping->tree_lock
-> lock_page_cgroup(A)
This patch tries to fix above deadlock by moving memcg's hook to out of
mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected
by page lock, not tree_lock.
After this patch, lock_page_cgroup() is not called under mapping->tree_lock.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This wasn't exported before and is useful (used by the experimental ext3
data=guarded code)
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Acked-by: Theodore Tso <tytso@mit.edu>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix filemap.c kernel-doc warnings:
Warning(mm/filemap.c:575): No description found for parameter 'page'
Warning(mm/filemap.c:575): No description found for parameter 'waiter'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds Kconfig and Makefile entries and exports to
VFS functions to be used by POHMELFS.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Add a function to install a monitor on the page lock waitqueue for a particular
page, thus allowing the page being unlocked to be detected.
This is used by CacheFiles to detect read completion on a page in the backing
filesystem so that it can then copy the data to the waiting netfs page.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
Recruit a page flag to aid in cache management. The following extra flag is
defined:
(1) PG_fscache (PG_private_2)
The marked page is backed by a local cache and is pinning resources in the
cache driver.
If PG_fscache is set, then things that checked for PG_private will now also
check for that. This includes things like truncation and page invalidation.
The function page_has_private() had been added to make the checks for both
PG_private and PG_private_2 at the same time.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
Impact: standardize IO on cached ops
On modern CPUs it is almost always a bad idea to use non-temporal stores,
as the regression in this commit has shown it:
30d697f: x86: fix performance regression in write() syscall
The kernel simply has no good information about whether using non-temporal
stores is a good idea or not - and trying to add heuristics only increases
complexity and inserts fragility.
The regression on cached write()s took very long to be found - over two
years. So dont take any chances and let the hardware decide how it makes
use of its caches.
The only exception is drivers/gpu/drm/i915/i915_gem.c: there were we are
absolutely sure that another entity (the GPU) will pick up the dirty
data immediately and that the CPU will not touch that data before the
GPU will.
Also, keep the _nocache() primitives to make it easier for people to
experiment with these details. There may be more clear-cut cases where
non-cached copies can be used, outside of filemap.c.
Cc: Salman Qazi <sqazi@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, enable future change
Add a 'total bytes copied' parameter to __copy_from_user_*nocache(),
and update all the callsites.
The parameter is not used yet - architecture code can use it to
more intelligently decide whether the copy should be cached or
non-temporal.
Cc: Salman Qazi <sqazi@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
System calls with an unsigned long long argument can't be converted with
the standard wrappers since that would include a cast to long, which in
turn means that we would lose the upper 32 bit on 32 bit architectures.
Also semctl can't use the standard wrapper since it has a 'union'
parameter.
So we handle them as special case and add some extra wrappers instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Convert all system calls to return a long. This should be a NOP since all
converted types should have the same size anyway.
With the exception of sys_exit_group which returned void. But that doesn't
matter since the system call doesn't return.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
My patch, memcg-fix-gfp_mask-of-callers-of-charge.patch changed gfp_mask
of callers of charge to be GFP_HIGHUSER_MOVABLE for showing what will
happen at memory reclaim.
But in recent discussion, it's NACKed because it sounds ugly.
This patch is for reverting it and add some clean up to gfp_mask of
callers of charge. No behavior change but need review before generating
HUNK in deep queue.
This patch also adds explanation to meaning of gfp_mask passed to charge
functions in memcontrol.h.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Frustratingly, gfp_t is really divided into two classes of flags. One are
the context dependent ones (can we sleep? can we enter filesystem? block
subsystem? should we use some extra reserves, etc.). The other ones are
the type of memory required and depend on how the algorithm is implemented
rather than the point at which the memory is allocated (highmem? dma
memory? etc).
Some of the functions which allocate a page and add it to page cache take
a gfp_t, but sometimes those functions or their callers aren't really
doing the right thing: when allocating pagecache page, the memory type
should be mapping_gfp_mask(mapping). When allocating radix tree nodes,
the memory type should be kernel mapped (not highmem) memory. The gfp_t
argument should only really be needed for context dependent options.
This patch doesn't really solve that tangle in a nice way, but it does
attempt to fix a couple of bugs.
- find_or_create_page changes its radix-tree allocation to only include
the main context dependent flags in order so the pagecache page may be
allocated from arbitrary types of memory without affecting the
radix-tree. In practice, slab allocations don't come from highmem
anyway, and radix-tree only uses slab allocations. So there isn't a
practical change (unless some fs uses GFP_DMA for pages).
- grab_cache_page_nowait() is changed to allocate radix-tree nodes with
GFP_NOFS, because it is not supposed to reenter the filesystem. This
bug could cause lock recursion if a filesystem is not expecting the
function to reenter the fs (as-per documentation).
Filesystems should be careful about exactly what semantics they want and
what they get when fiddling with gfp_t masks to allocate pagecache. One
should be as liberal as possible with the type of memory that can be used,
and same for the the context specific flags.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Direct IO can invalidate and sync a lot of pagecache pages in the mapping.
A 4K direct IO will actually try to sync and/or invalidate the pagecache
of the entire file, for example (which might be many GB or TB large).
Improve this by doing range syncs. Also, memory no longer has to be
unmapped to catch the dirty bits for syncing, as dirty bits would remain
coherent due to dirty mmap accounting.
This fixes the immediate DM deadlocks when doing direct IO reads to block
device with a mounted filesystem, if only by papering over the problem
somewhat rather than addressing the fsync starvation cases.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In write_cache_pages, nr_to_write is heeded even for data-integrity syncs,
so the function will return success after writing out nr_to_write pages,
even if that was not sufficient to guarantee data integrity.
The callers tend to set it to values that could break data interity
semantics easily in practice. For example, nr_to_write can be set to
mapping->nr_pages * 2, however if a file has a single, dirty page, then
fsync is called, subsequent pages might be concurrently added and dirtied,
then write_cache_pages might writeout two of these newly dirty pages,
while not writing out the old page that should have been written out.
Fix this by ignoring nr_to_write if it is a data integrity sync.
This is a data integrity bug.
The reason this has been done in the past is to avoid stalling sync
operations behind page dirtiers.
"If a file has one dirty page at offset 1000000000000000 then someone
does an fsync() and someone else gets in first and starts madly writing
pages at offset 0, we want to write that page at 1000000000000000.
Somehow."
What we do today is return success after an arbitrary amount of pages are
written, whether or not we have provided the data-integrity semantics that
the caller has asked for. Even this doesn't actually fix all stall cases
completely: in the above situation, if the file has a huge number of pages
in pagecache (but not dirty), then mapping->nrpages is going to be huge,
even if pages are being dirtied.
This change does indeed make the possibility of long stalls lager, and
that's not a good thing, but lying about data integrity is even worse. We
have to either perform the sync, or return -ELINUXISLAME so at least the
caller knows what has happened.
There are subsequent competing approaches in the works to solve the stall
problems properly, without compromising data integrity.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Doing a mark_page_accessed at fault-time, then doing SetPageReferenced at
unmap-time if the pte is young has a number of problems.
mark_page_accessed is supposed to be roughly the equivalent of a young pte
for unmapped references. Unfortunately it doesn't come with any context:
after being called, reclaim doesn't know who or why the page was touched.
So calling mark_page_accessed not only adds extra lru or PG_referenced
manipulations for pages that are already going to have pte_young ptes anyway,
but it also adds these references which are difficult to work with from the
context of vma specific references (eg. MADV_SEQUENTIAL pte_young may not
wish to contribute to the page being referenced).
Then, simply doing SetPageReferenced when zapping a pte and finding it is
young, is not a really good solution either. SetPageReferenced does not
correctly promote the page to the active list for example. So after removing
mark_page_accessed from the fault path, several mmap()+touch+munmap() would
have a very different result from several read(2) calls for example, which
is not really desirable.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Johannes Weiner <hannes@saeurebad.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
inotify: fix type errors in interfaces
fix breakage in reiserfs_new_inode()
fix the treatment of jfs special inodes
vfs: remove duplicate code in get_fs_type()
add a vfs_fsync helper
sys_execve and sys_uselib do not call into fsnotify
zero i_uid/i_gid on inode allocation
inode->i_op is never NULL
ntfs: don't NULL i_op
isofs check for NULL ->i_op in root directory is dead code
affs: do not zero ->i_op
kill suid bit only for regular files
vfs: lseek(fd, 0, SEEK_CUR) race condition
We don't have to do it because it is useless for non regular files.
In fact block device may trigger this path without dentry->d_inode->i_mutex.
(akpm: concerns were expressed (by me) about S_ISDIR inodes)
Signed-off-by: Dmitri Monakhov <dmonakhov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
With the write_begin/write_end aops, page_symlink was broken because it
could no longer pass a GFP_NOFS type mask into the point where the
allocations happened. They are done in write_begin, which would always
assume that the filesystem can be entered from reclaim. This bug could
cause filesystem deadlocks.
The funny thing with having a gfp_t mask there is that it doesn't really
allow the caller to arbitrarily tinker with the context in which it can be
called. It couldn't ever be GFP_ATOMIC, for example, because it needs to
take the page lock. The only thing any callers care about is __GFP_FS
anyway, so turn that into a single flag.
Add a new flag for write_begin, AOP_FLAG_NOFS. Filesystems can now act on
this flag in their write_begin function. Change __grab_cache_page to
accept a nofs argument as well, to honour that flag (while we're there,
change the name to grab_cache_page_write_begin which is more instructive
and does away with random leading underscores).
This is really a more flexible way to go in the end anyway -- if a
filesystem happens to want any extra allocations aside from the pagecache
ones in ints write_begin function, it may now use GFP_KERNEL (rather than
GFP_NOFS) for common case allocations (eg. ocfs2_alloc_write_ctxt, for a
random example).
[kosaki.motohiro@jp.fujitsu.com: fix ubifs]
[kosaki.motohiro@jp.fujitsu.com: fix fuse]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@kernel.org> [2.6.28.x]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Cleaned up the calling convention: just pass in the AOP flags
untouched to the grab_cache_page_write_begin() function. That
just simplifies everybody, and may even allow future expansion of the
logic. - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nothing uses prepare_write or commit_write. Remove them from the tree
completely.
[akpm@linux-foundation.org: schedule simple_prepare_write() for unexporting]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch tries to make page->mapping to be NULL before
mem_cgroup_uncharge_cache_page() is called.
"page->mapping == NULL" is a good check for "whether the page is still
radix-tree or not". This patch also adds BUG_ON() to
mem_cgroup_uncharge_cache_page();
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
trylock_page, unlock_page open and close a critical section. Hence,
we can use the lock bitops to get the desired memory ordering.
Also, mark trylock as likely to succeed (and remove the annotation from
callers).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Split the LRU lists in two, one set for pages that are backed by real file
systems ("file") and one for pages that are backed by memory and swap
("anon"). The latter includes tmpfs.
The advantage of doing this is that the VM will not have to scan over lots
of anonymous pages (which we generally do not want to swap out), just to
find the page cache pages that it should evict.
This patch has the infrastructure and a basic policy to balance how much
we scan the anon lists and how much we scan the file lists. The big
policy changes are in separate patches.
[lee.schermerhorn@hp.com: collect lru meminfo statistics from correct offset]
[kosaki.motohiro@jp.fujitsu.com: prevent incorrect oom under split_lru]
[kosaki.motohiro@jp.fujitsu.com: fix pagevec_move_tail() doesn't treat unevictable page]
[hugh@veritas.com: memcg swapbacked pages active]
[hugh@veritas.com: splitlru: BDI_CAP_SWAP_BACKED]
[akpm@linux-foundation.org: fix /proc/vmstat units]
[nishimura@mxp.nes.nec.co.jp: memcg: fix handling of shmem migration]
[kosaki.motohiro@jp.fujitsu.com: adjust Quicklists field of /proc/meminfo]
[kosaki.motohiro@jp.fujitsu.com: fix style issue of get_scan_ratio()]
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The 'filp' argument to do_generic_file_read() is never NULL.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If lock_page_killable() fails because the task was killed by SIGKILL or
any other fatal signal, do_generic_file_read() returns -EIO.
This seems to be OK, because in fact the userspace won't see this error,
the task will dequeue SIGKILL and exit.
However, /sbin/init is different, it will dequeue SIGKILL, ignore it, and
return to the user-space with the bogus -EIO.
Change the code to return the error code from lock_page_killable(), -EINTR.
This doesn't fix the bug, but perhaps makes sense anyway. Imho, with this
change the code looks a bit more logical, and the "good" init should handle
the spurious EINTR or short read.
Afaics we can also change lock_page_killable() to return -ERESTARTNOINTR,
but this can't prevent the short reads.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Dio write returns EIO when try_to_release_page fails because bh is
still referenced.
The patch
commit 3f31fddfa2
Author: Mingming Cao <cmm@us.ibm.com>
Date: Fri Jul 25 01:46:22 2008 -0700
jbd: fix race between free buffer and commit transaction
was merged into 2.6.27-rc1, but I noticed that this patch is not enough
to fix the race.
I did fsstress test heavily to 2.6.27-rc1, and found that dio write still
sometimes got EIO through this test.
The patch above fixed race between freeing buffer(dio) and committing
transaction(jbd) but I discovered that there is another race, freeing
buffer(dio) and ext3/4_ordered_writepage.
: background_writeout()
->write_cache_pages()
->ext3_ordered_writepage()
walk_page_buffers() -> take a bh ref
block_write_full_page() -> unlock_page
: <- end_page_writeback
: <- race! (dio write->try_to_release_page fails)
walk_page_buffers() ->release a bh ref
ext3_ordered_writepage holds bh ref and does unlock_page remaining
taking a bh ref, so this causes the race and failure of
try_to_release_page.
To fix this race, I used the approach of falling back to buffered
writes if try_to_release_page() fails on a page.
[akpm@linux-foundation.org: cleanups]
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Converting page lock to new locking bitops requires a change of page flag
operation naming, so we might as well convert it to something nicer
(!TestSetPageLocked_Lock => trylock_page, SetPageLocked => set_page_locked).
This also facilitates lockdeping of page lock.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The iov_iter_advance() function would look at the iov->iov_len entry
even though it might have iterated over the whole array, and iov was
pointing past the end. This would cause DEBUG_PAGEALLOC to trigger a
kernel page fault if the allocation was at the end of a page, and the
next page was unallocated.
The quick fix is to just change the order of the tests: check that there
is any iovec data left before we check the iov entry itself.
Thanks to Alexey Dobriyan for finding this case, and testing the fix.
Reported-and-tested-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we read some part of a file through pagecache, if there is a
pagecache of corresponding index but this page is not uptodate, read IO
is issued and this page will be uptodate.
I think this is good for pagesize == blocksize environment but there is
room for improvement on pagesize != blocksize environment. Because in
this case a page can have multiple buffers and even if a page is not
uptodate, some buffers can be uptodate.
So I suggest that when all buffers which correspond to a part of a file
that we want to read are uptodate, use this pagecache and copy data from
this pagecache to user buffer even if a page is not uptodate. This can
reduce read IO and improve system throughput.
I wrote a benchmark program and got result number with this program.
This benchmark do:
1: mount and open a test file.
2: create a 512MB file.
3: close a file and umount.
4: mount and again open a test file.
5: pwrite randomly 300000 times on a test file. offset is aligned
by IO size(1024bytes).
6: measure time of preading randomly 100000 times on a test file.
The result was:
2.6.26
330 sec
2.6.26-patched
226 sec
Arch:i386
Filesystem:ext3
Blocksize:1024 bytes
Memory: 1GB
On ext3/4, a file is written through buffer/block. So random read/write
mixed workloads or random read after random write workloads are optimized
with this patch under pagesize != blocksize environment. This test result
showed this.
The benchmark program is as follows:
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#define LEN 1024
#define LOOP 1024*512 /* 512MB */
main(void)
{
unsigned long i, offset, filesize;
int fd;
char buf[LEN];
time_t t1, t2;
if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) {
perror("cannot mount\n");
exit(1);
}
memset(buf, 0, LEN);
fd = open("/root/test1/testfile", O_CREAT|O_RDWR|O_TRUNC);
if (fd < 0) {
perror("cannot open file\n");
exit(1);
}
for (i = 0; i < LOOP; i++)
write(fd, buf, LEN);
close(fd);
if (umount("/root/test1/") < 0) {
perror("cannot umount\n");
exit(1);
}
if (mount("/dev/sda1", "/root/test1/", "ext3", 0, 0) < 0) {
perror("cannot mount\n");
exit(1);
}
fd = open("/root/test1/testfile", O_RDWR);
if (fd < 0) {
perror("cannot open file\n");
exit(1);
}
filesize = LEN * LOOP;
for (i = 0; i < 300000; i++){
offset = (random() % filesize) & (~(LEN - 1));
pwrite(fd, buf, LEN, offset);
}
printf("start test\n");
time(&t1);
for (i = 0; i < 100000; i++){
offset = (random() % filesize) & (~(LEN - 1));
pread(fd, buf, LEN, offset);
}
time(&t2);
printf("%ld sec\n", t2-t1);
close(fd);
if (umount("/root/test1/") < 0) {
perror("cannot umount\n");
exit(1);
}
}
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@ucw.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All calls to remove_suid() are made with a file pointer, because
(similarly to file_update_time) it is called when the file is written.
Clean up callers by passing in a file instead of a dentry.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
mapping->tree_lock has no read lockers. convert the lock from an rwlock
to a spinlock.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Combine page_cache_get_speculative with lockless radix tree lookups to
introduce lockless page cache lookups (ie. no mapping->tree_lock on the
read-side).
The only atomicity changes this introduces is that the gang pagecache
lookup functions now behave as if they are implemented with multiple
find_get_page calls, rather than operating on a snapshot of the pages. In
practice, this atomicity guarantee is not used anyway, and it is to
replace individual lookups, so these semantics are natural.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we can be sure that elevating the page_count on a pagecache page will
pin it, we can speculatively run this operation, and subsequently check to
see if we hit the right page rather than relying on holding a lock or
otherwise pinning a reference to the page.
This can be done if get_page/put_page behaves consistently throughout the
whole tree (ie. if we "get" the page after it has been used for something
else, we must be able to free it with a put_page).
Actually, there is a period where the count behaves differently: when the
page is free or if it is a constituent page of a compound page. We need
an atomic_inc_not_zero operation to ensure we don't try to grab the page
in either case.
This patch introduces the core locking protocol to the pagecache (ie.
adds page_cache_get_speculative, and tweaks some update-side code to make
it work).
Thanks to Hugh for pointing out an improvement to the algorithm setting
page_count to zero when we have control of all references, in order to
hold off speculative getters.
[kamezawa.hiroyu@jp.fujitsu.com: fix migration_entry_wait()]
[hugh@veritas.com: fix add_to_page_cache]
[akpm@linux-foundation.org: repair a comment]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
journal_try_to_free_buffers() could race with jbd commit transaction when
the later is holding the buffer reference while waiting for the data
buffer to flush to disk. If the caller of journal_try_to_free_buffers()
request tries hard to release the buffers, it will treat the failure as
error and return back to the caller. We have seen the directo IO failed
due to this race. Some of the caller of releasepage() also expecting the
buffer to be dropped when passed with GFP_KERNEL mask to the
releasepage()->journal_try_to_free_buffers().
With this patch, if the caller is passing the __GFP_WAIT and __GFP_FS to
indicating this call could wait, in case of try_to_free_buffers() failed,
let's waiting for journal_commit_transaction() to finish commit the
current committing transaction, then try to free those buffers again.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Reviewed-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As akpm points out, there's really no need for generic_file_aio_read to
make a special case of count 0: just loop through nr_segs doing nothing.
And as Harvey Harrison points out, there's no need to reset retval to 0
where it's already 0.
Setting count (or ocount) to 0 before calling generic_segment_checks is
unnecessary too; but reluctantly I'll leave that removal to someone with a
wider range of gcc versions to hand - 4.1.2 and 4.2.1 don't warn about it,
but perhaps others do - I forget which are the warniest versions.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Tested-by: Lawrence Greenfield <leg@google.com>
Cc: Christoph Rohland <hans-christoph.rohland@sap.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generic_file_direct_IO is a common helper around the invocation of
->direct_IO. But there's almost nothing shared between the read and write
side, so we're better off without this helper.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make filemap_fdatawrite_range() function public, so that it can later
be used in ordered mode rewrite by JBD/JBD2.
Signed-off-by: Jan Kara <jack@suse.cz>
filemap_fault will go into an infinite loop if ->readpage() fails
asynchronously.
AFAICS the bug was introduced by this commit, which removed the wait after the
final readpage:
commit d00806b183
Author: Nick Piggin <npiggin@suse.de>
Date: Thu Jul 19 01:46:57 2007 -0700
mm: fix fault vs invalidate race for linear mappings
Fix by reintroducing the wait_on_page_locked() after ->readpage() to make sure
the page is up-to-date before jumping back to the beginning of the function.
I've noticed this while testing nfs exporting on fuse. The patch
fixes it.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generic_file_splice_write() duplicates remove_suid() just because it
doesn't hold i_mutex. But it grabs i_mutex inside splice_from_pipe()
anyway, so this is rather pointless.
Move locking to generic_file_splice_write() and call remove_suid() and
__splice_from_pipe() instead.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Clean up messy conditional calling of test_clear_page_writeback() from both
rotate_reclaimable_page() and end_page_writeback().
The only user of rotate_reclaimable_page() is end_page_writeback() so this is
OK.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix various kernel-doc notation in mm/:
filemap.c: add function short description; convert 2 to kernel-doc
fremap.c: change parameter 'prot' to @prot
pagewalk.c: change "-" in function parameters to ":"
slab.c: fix short description of kmem_ptr_validate()
swap.c: fix description & parameters of put_pages_list()
swap_state.c: fix function parameters
vmalloc.c: change "@returns" to "Returns:" since that is not a parameter
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
iov_iter_advance() skips over zero-length iovecs, however it does not properly
terminate at the end of the iovec array. Fix this by checking against
i->count before we skip a zero-length iov.
The bug was reproduced with a test program that continually randomly creates
iovs to writev. The fix was also verified with the same program and also it
could verify that the correct data was contained in the file after each
writev.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Tested-by: "Kevin Coffman" <kwc@citi.umich.edu>
Cc: "Alexey Dobriyan" <adobriyan@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fastcall always expands to empty, remove it.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
do_generic_mapping_read was used by gfs2 for internals reads, but this use
of the interface was rather suboptimal (as was the whole interface) and has
been replaced by an internal helper now. This patch kills
do_generic_mapping_read and surrounding damage in preparation of additional
cleanups for the buffered read path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert variables containing page indexes to pgoff_t.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Need to strip __GFP_HIGHMEM flag while passing to mem_container_cache_charge().
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move mem_controller_cache_charge() above radix_tree_preload().
radix_tree_preload() disables preemption, even though the gfp_mask passed
contains __GFP_WAIT, we cannot really do __GFP_WAIT allocations, thus we
hit a BUG_ON() in kmem_cache_alloc().
This patch moves mem_controller_cache_charge() to above radix_tree_preload()
for cache charging.
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nick Piggin pointed out that swap cache and page cache addition routines
could be called from non GFP_KERNEL contexts. This patch makes the
charging routine aware of the gfp context. Charging might fail if the
cgroup is over it's limit, in which case a suitable error is returned.
This patch was tested on a Powerpc box. I am still looking at being able
to test the path, through which allocations happen in non GFP_KERNEL
contexts.
[kamezawa.hiroyu@jp.fujitsu.com: problem with ZONE_MOVABLE]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Choose if we want cached pages to be accounted or not. By default both are
accounted for. A new set of tunables are added.
echo -n 1 > mem_control_type
switches the accounting to account for only mapped pages
echo -n 3 > mem_control_type
switches the behaviour back
[bunk@kernel.org: mm/memcontrol.c: clenups]
[akpm@linux-foundation.org: fix sparc32 build]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add the accounting hooks. The accounting is carried out for RSS and Page
Cache (unmapped) pages. There is now a common limit and accounting for both.
The RSS accounting is accounted at page_add_*_rmap() and page_remove_rmap()
time. Page cache is accounted at add_to_page_cache(),
__delete_from_page_cache(). Swap cache is also accounted for.
Each page's page_cgroup is protected with the last bit of the
page_cgroup pointer, this makes handling of race conditions involving
simultaneous mappings of a page easier. A reference count is kept in the
page_cgroup to deal with cases where a page might be unmapped from the RSS
of all tasks, but still lives in the page cache.
Credits go to Vaidyanathan Srinivasan for helping with reference counting work
of the page cgroup. Almost all of the page cache accounting code has help
from Vaidyanathan Srinivasan.
[hugh@veritas.com: fix swapoff breakage]
[akpm@linux-foundation.org: fix locking]
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: <Valdis.Kletnieks@vt.edu>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
