KM_USER1 is never used for vwrite() path so the caller doesn't need to
guarantee it is not used. Only the caller should guarantee is KM_USER0
and it is commented already.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Acked-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>
For range-cyclic writeback (e.g. kupdate), the writeback code sets a
continuation point of the next writeback to mapping->writeback_index which
is set the page after the last written page. This happens so that we
evenly write the whole file even if pages in it get continuously
redirtied.
However, in some cases, sequential writer is writing in the middle of the
page and it just redirties the last written page by continuing from that.
For example with an application which uses a file as a big ring buffer we
see:
[1st writeback session]
...
flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898514 + 8
flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898522 + 8
flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898530 + 8
flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898538 + 8
flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898546 + 8
kworker/0:1-11 4571: block_rq_issue: 8,0 W 0 () 94898514 + 40
>> flush-8:0-2743 4571: block_bio_queue: 8,0 W 94898554 + 8
>> flush-8:0-2743 4571: block_rq_issue: 8,0 W 0 () 94898554 + 8
[2nd writeback session after 35sec]
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898562 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898570 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898578 + 8
...
kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94898562 + 640
kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94899202 + 72
...
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899962 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899970 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899978 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899986 + 8
flush-8:0-2743 4606: block_bio_queue: 8,0 W 94899994 + 8
kworker/0:1-11 4606: block_rq_issue: 8,0 W 0 () 94899962 + 40
>> flush-8:0-2743 4606: block_bio_queue: 8,0 W 94898554 + 8
>> flush-8:0-2743 4606: block_rq_issue: 8,0 W 0 () 94898554 + 8
So we seeked back to 94898554 after we wrote all the pages at the end of
the file.
This extra seek seems unnecessary. If we continue writeback from the last
written page, we can avoid it and do not cause harm to other cases. The
original intent of even writeout over the whole file is preserved and if
the page does not get redirtied pagevec_lookup_tag() just skips it.
As an exceptional case, when I/O error happens, set done_index to the next
page as the comment in the code suggests.
Tested-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
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>
scan_swap_map() is a large function (224 lines), with several loops and a
complex control flow involving several gotos.
Given all that, it is a bit silly that it is marked as inline. The
compiler agrees with me: on a x86-64 compile, it did not inline the
function.
Remove the "inline" and let the compiler decide instead.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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>
The block in sys_swapon which does the final adjustments to the
swap_info_struct and to swap_list is the same as the block which
re-inserts it again at sys_swapoff on failure of try_to_unuse(). Move
this code to a separate function, and use it both in sys_swapon and
sys_swapoff.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The block in sys_swapon which does the final adjustments to the
swap_info_struct and to swap_list is the same as the block which
re-inserts it again at sys_swapoff on failure of try_to_unuse(), except
for the order of the operations within the lock. Since the order should
not matter, arbitrarily change sys_swapoff to match sys_swapon, in
preparation to making both share the same code.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The block in sys_swapon which does the final adjustments to the
swap_info_struct and to swap_list is the same as the block which
re-inserts it again at sys_swapoff on failure of try_to_unuse(). To be
able to make both share the same code, move the printk() call in the
middle of it to just after it.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It still exists within setup_swap_map_and_extents(), but after it
nr_good_pages == p->pages.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since there is no cleanup to do, there is no reason to jump to a label.
Return directly instead.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the code which parses the bad block list and the extents to a
separate function. Only code movement, no functional changes.
This change uses the fact that, after the success path, nr_good_pages ==
p->pages.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The call to swap_cgroup_swapon is in the middle of loading the swap map
and extents. As it only does memory allocation and does not depend on
the swapfile layout (map/extents), it can be called earlier (or later).
Move it to just after the allocation of swap_map, since it is
conceptually similar (allocates a map).
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since there is no cleanup to do, there is no reason to jump to a label.
Return directly instead.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the code which parses and checks the swapfile header (except for
the bad block list) to a separate function. Only code movement, no
functional changes.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no reason I can see to read inode->i_size long before it is
needed. Move its read to just before it is needed, to reduce the
variable lifetime.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since there is no cleanup to do, there is no reason to jump to a label.
Return directly instead.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the code which claims the bdev (S_ISBLK) or locks the inode
(S_ISREG) to a separate function. Only code movement, no functional
changes.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sys_swapon currently has two error labels, bad_swap and bad_swap_2.
bad_swap does the same as bad_swap_2 plus destroy_swap_extents() and
swap_cgroup_swapoff(); both are noops in the places where bad_swap_2 is
jumped to. With a single extra test for inode (matching the one in the
S_ISREG case below), all the error paths in the function can go to
bad_swap.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only way error is 0 in the cleanup blocks is when the function is
returning successfully. In this case, the cleanup blocks were setting
S_SWAPFILE in the S_ISREG case. But this is not a cleanup.
Move the setting of S_SWAPFILE to just before the "goto out;" to make
this more clear. At this point, we do not need to test for inode because
it will never be NULL.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The bdev variable is always equivalent to (S_ISBLK(inode->i_mode) ?
p->bdev : NULL), as long as it being set is moved to a bit earlier. Use
this fact to remove the bdev variable.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the setting of the error variable nearer the goto in a few places.
Avoids calling PTR_ERR() if not IS_ERR() in two places, and makes the
error condition more explicit in two other places.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since mutex_lock(&inode->i_mutex) is called just after setting inode,
did_down is always equivalent to (inode && S_ISREG(inode->i_mode)).
Use this fact to remove the did_down variable.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now there is nothing which jumps to the cleanup blocks before the name
variable is set. There is no need to set it initially to NULL anymore.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since there is no cleanup to do, there is no reason to jump to a label.
Return directly instead.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At this point in sys_swapon, there is nothing to free. Return directly
instead of jumping to the cleanup block at the end of the function.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the swap_info allocation to its own function. Only code movement,
no functional changes.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Within sys_swapon, after the swap_info entry has been allocated, we
always have type == p->type and swap_info[type] == p. Use this fact to
reduce the dependency on the "type" local variable within the function,
as a preparation to move the allocation of the swap_info entry to a
separate function.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Changelogs belong in the git history instead of in the source code.
Also, "The swapon system call" is redundant with
"SYSCALL_DEFINE2(swapon, ...)".
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Gaah. That's a _historical_ comment. But the patch-series depends on removal ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch series refactors the sys_swapon function.
sys_swapon is currently a very large function, with 313 lines (more than
12 25-line screens), which can make it a bit hard to read. This patch
series reduces this size by half, by extracting large chunks of related
code to new helper functions.
One of these chunks of code was nearly identical to the part of
sys_swapoff which is used in case of a failure return from
try_to_unuse(), so this patch series also makes both share the same
code.
As a side effect of all this refactoring, the compiled code gets a bit
smaller (from v1 of this patch series):
text data bss dec hex filename
14012 944 276 15232 3b80 mm/swapfile.o.before
13941 944 276 15161 3b39 mm/swapfile.o.after
This patch:
Use vzalloc() instead of vmalloc/memset.
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass __GFP_OTHER_NODE for transparent hugepages NUMA allocations done by the
hugepages daemon. This way the low level accounting for local versus
remote pages works correctly.
Contains improvements from Andrea Arcangeli
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new __GFP_OTHER_NODE flag to tell the low level numa statistics in
zone_statistics() that an allocation is on behalf of another thread. This
way the local and remote counters can be still correct, even when
background daemons like khugepaged are changing memory mappings.
This only affects the accounting, but I think it's worth doing that right
to avoid confusing users.
I first tried to just pass down the right node, but this required a lot of
changes to pass down this parameter and at least one addition of a 10th
argument to a 9 argument function. Using the flag is a lot less
intrusive.
Open: should be also used for migration?
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__GFP_NO_KSWAPD allocations are usually very expensive and not mandatory
to succeed as they have graceful fallback. Waiting for I/O in those,
tends to be overkill in terms of latencies, so we can reduce their latency
by disabling sync migrate.
Unfortunately, even with async migration it's still possible for the
process to be blocked waiting for a request slot (e.g. get_request_wait
in the block layer) when ->writepage is called. To prevent
__GFP_NO_KSWAPD blocking, this patch prevents ->writepage being called on
dirty page cache for asynchronous migration.
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=31142
[mel@csn.ul.ie: Avoid writebacks for NFS, retry locked pages, use bool]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: Clemens Ladisch <cladisch@googlemail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reported-by: Alex Villacis Lasso <avillaci@ceibo.fiec.espol.edu.ec>
Tested-by: Alex Villacis Lasso <avillaci@ceibo.fiec.espol.edu.ec>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
compaction_alloc() isolates pages for migration in isolate_migratepages.
While it's scanning, IRQs are disabled on the mistaken assumption the
scanning should be short. Tests show this to be true for the most part
but contention times on the LRU lock can be increased. Before this patch,
the IRQ disabled times for a simple test looked like
Total sampled time IRQs off (not real total time): 5493
Event shrink_inactive_list..shrink_zone 1596 us count 1
Event shrink_inactive_list..shrink_zone 1530 us count 1
Event shrink_inactive_list..shrink_zone 956 us count 1
Event shrink_inactive_list..shrink_zone 541 us count 1
Event shrink_inactive_list..shrink_zone 531 us count 1
Event split_huge_page..add_to_swap 232 us count 1
Event save_args..call_softirq 36 us count 1
Event save_args..call_softirq 35 us count 2
Event __wake_up..__wake_up 1 us count 1
This patch reduces the worst-case IRQs-disabled latencies by releasing the
lock every SWAP_CLUSTER_MAX pages that are scanned and releasing the CPU if
necessary. The cost of this is that the processing performing compaction will
be slower but IRQs being disabled for too long a time has worse consequences
as the following report shows;
Total sampled time IRQs off (not real total time): 4367
Event shrink_inactive_list..shrink_zone 881 us count 1
Event shrink_inactive_list..shrink_zone 875 us count 1
Event shrink_inactive_list..shrink_zone 868 us count 1
Event shrink_inactive_list..shrink_zone 555 us count 1
Event split_huge_page..add_to_swap 495 us count 1
Event compact_zone..compact_zone_order 269 us count 1
Event split_huge_page..add_to_swap 266 us count 1
Event shrink_inactive_list..shrink_zone 85 us count 1
Event save_args..call_softirq 36 us count 2
Event __wake_up..__wake_up 1 us count 1
[akpm@linux-foundation.org: simplify with s/unlocked/locked/]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: Clemens Ladisch <cladisch@googlemail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
compaction_alloc() isolates free pages to be used as migration targets.
While its scanning, IRQs are disabled on the mistaken assumption the
scanning should be short. Analysis showed that IRQs were in fact being
disabled for substantial time. A simple test was run using large
anonymous mappings with transparent hugepage support enabled to trigger
frequent compactions. A monitor sampled what the worst IRQ-off latencies
were and a post-processing tool found the following;
Total sampled time IRQs off (not real total time): 22355
Event compaction_alloc..compaction_alloc 8409 us count 1
Event compaction_alloc..compaction_alloc 7341 us count 1
Event compaction_alloc..compaction_alloc 2463 us count 1
Event compaction_alloc..compaction_alloc 2054 us count 1
Event shrink_inactive_list..shrink_zone 1864 us count 1
Event shrink_inactive_list..shrink_zone 88 us count 1
Event save_args..call_softirq 36 us count 1
Event save_args..call_softirq 35 us count 2
Event __make_request..__blk_run_queue 24 us count 1
Event __alloc_pages_nodemask..__alloc_pages_nodemask 6 us count 1
i.e. compaction is disabled IRQs for a prolonged period of time - 8ms in
one instance. The full report generated by the tool can be found at
http://www.csn.ul.ie/~mel/postings/minfree-20110225/irqsoff-vanilla-micro.report
This patch reduces the time IRQs are disabled by simply disabling IRQs at
the last possible minute. An updated IRQs-off summary report then looks
like;
Total sampled time IRQs off (not real total time): 5493
Event shrink_inactive_list..shrink_zone 1596 us count 1
Event shrink_inactive_list..shrink_zone 1530 us count 1
Event shrink_inactive_list..shrink_zone 956 us count 1
Event shrink_inactive_list..shrink_zone 541 us count 1
Event shrink_inactive_list..shrink_zone 531 us count 1
Event split_huge_page..add_to_swap 232 us count 1
Event save_args..call_softirq 36 us count 1
Event save_args..call_softirq 35 us count 2
Event __wake_up..__wake_up 1 us count 1
A full report is again available at
http://www.csn.ul.ie/~mel/postings/minfree-20110225/irqsoff-minimiseirq-free-v1r4-micro.report
As should be obvious, IRQ disabled latencies due to compaction are
almost elimimnated for this particular test.
[aarcange@redhat.com: Fix initialisation of isolated]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujisu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arthur Marsh <arthur.marsh@internode.on.net>
Cc: Clemens Ladisch <cladisch@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Callers of find_get_pages(), or its wrapper pagevec_lookup() - notably
truncate_inode_pages_range() - stop looking further when it returns 0.
But if an interrupt comes just after its radix_tree_gang_lookup_slot(),
especially if we have preemptible RCU enabled, isn't it conceivable that
all 14 pages returned could be removed from the page cache by
shrink_page_list(), before find_get_pages() gets to process them? So
causing it to return 0 although there may be plenty more pages beyond.
Make find_get_pages() and find_get_pages_tag() check for this unlikely
case, and restart should it occur; but callers of find_get_pages_contig()
have no such expectation, it's okay for that to return 0 early.
I have not seen this in practice, just worried by the possibility.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Salman Qazi <sqazi@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The radix_tree_deref_retry() case in find_get_pages() has a strange little
excrescence, not seen in the other gang lookups: it looks like the start
of an abandoned attempt to guarantee forward progress in a case that
cannot arise.
ret should always be 0 here: if it isn't, then going back to restart will
leak references to pages already gotten. There used to be a comment
saying nr_found is necessarily 1 here: that's not quite true, but the
radix_tree_deref_retry() case is peculiar to the entry at index 0, when we
race with it being moved out of the radix_tree root or back.
Remove the worrisome two lines, add a brief comment here and in
find_get_pages_contig() and find_get_pages_tag(), and a WARN_ON in
find_get_pages() should it ever be seen elsewhere than at 0.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Salman Qazi <sqazi@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the user inserts a negative value into /proc/sys/vm/nr_hugepages it
will cause the kernel to allocate as many hugepages as possible and to
then update /proc/meminfo to reflect this.
This changes the behavior so that the negative input will result in
nr_hugepages value being unchanged.
Signed-off-by: Petr Holasek <pholasek@redhat.com>
Signed-off-by: Anton Arapov <anton@redhat.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When reclaiming for order-0 pages, kswapd requires that all zones be
balanced. Each cycle through balance_pgdat() does background ageing on
all zones if necessary and applies equal pressure on the inactive zone
unless a lot of pages are free already.
A "lot of free pages" is defined as a "balance gap" above the high
watermark which is currently 7*high_watermark. Historically this was
reasonable as min_free_kbytes was small. However, on systems using huge
pages, it is recommended that min_free_kbytes is higher and it is tuned
with hugeadm --set-recommended-min_free_kbytes. With the introduction of
transparent huge page support, this recommended value is also applied. On
X86-64 with 4G of memory, min_free_kbytes becomes 67584 so one would
expect around 68M of memory to be free. The Normal zone is approximately
35000 pages so under even normal memory pressure such as copying a large
file, it gets exhausted quickly. As it is getting exhausted, kswapd
applies pressure equally to all zones, including the DMA32 zone. DMA32 is
approximately 700,000 pages with a high watermark of around 23,000 pages.
In this situation, kswapd will reclaim around (23000*8 where 8 is the high
watermark + balance gap of 7 * high watermark) pages or 718M of pages
before the zone is ignored. What the user sees is that free memory far
higher than it should be.
To avoid an excessive number of pages being reclaimed from the larger
zones, explicitely defines the "balance gap" to be either 1% of the zone
or the low watermark for the zone, whichever is smaller. While kswapd
will check all zones to apply pressure, it'll ignore zones that meets the
(high_wmark + balance_gap) watermark.
To test this, 80G were copied from a partition and the amount of memory
being used was recorded. A comparison of a patch and unpatched kernel can
be seen at
http://www.csn.ul.ie/~mel/postings/minfree-20110222/memory-usage-hydra.ps
and shows that kswapd is not reclaiming as much memory with the patch
applied.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The 'flags' field is already checked, no need to do it again.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Bob Liu <lliubbo@gmail.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that the mere act of _looking_ at /proc/$pid/smaps will not destroy
transparent huge pages, tell how much of the VMA is actually mapped with
them.
This way, we can make sure that we're getting THPs where we
expect to see them.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds code to explicitly detect and handle pmd_trans_huge() pmds. It
then passes HPAGE_SIZE units in to the smap_pte_entry() function instead
of PAGE_SIZE.
This means that using /proc/$pid/smaps now will no longer cause THPs to be
broken down in to small pages.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an argument to the new smaps_pte_entry() function to let it account in
things other than PAGE_SIZE units. I changed all of the PAGE_SIZE sites,
even though not all of them can be reached for transparent huge pages,
just so this will continue to work without changes as THPs are improved.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We will use smaps_pte_entry() in a moment to handle both small and
transparent large pages. But, we must break it out of smaps_pte_range()
first.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now, if a mm_walk has either ->pte_entry or ->pmd_entry set, it will
unconditionally split any transparent huge pages it runs in to. In
practice, that means that anyone doing a
cat /proc/$pid/smaps
will unconditionally break down every huge page in the process and depend
on khugepaged to re-collapse it later. This is fairly suboptimal.
This patch changes that behavior. It teaches each ->pmd_entry handler
(there are five) that they must break down the THPs themselves. Also, the
_generic_ code will never break down a THP unless a ->pte_entry handler is
actually set.
This means that the ->pmd_entry handlers can now choose to deal with THPs
without breaking them down.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
invalidate_mapping_pages is very big hint to reclaimer. It means user
doesn't want to use the page any more. So in order to prevent working set
page eviction, this patch move the page into tail of inactive list by
PG_reclaim.
Please, remember that pages in inactive list are working set as well as
active list. If we don't move pages into inactive list's tail, pages near
by tail of inactive list can be evicted although we have a big clue about
useless pages. It's totally bad.
Now PG_readahead/PG_reclaim is shared. fe3cba17 added ClearPageReclaim
into clear_page_dirty_for_io for preventing fast reclaiming readahead
marker page.
In this series, PG_reclaim is used by invalidated page, too. If VM find
the page is invalidated and it's dirty, it sets PG_reclaim to reclaim
asap. Then, when the dirty page will be writeback,
clear_page_dirty_for_io will clear PG_reclaim unconditionally. It
disturbs this serie's goal.
I think it's okay to clear PG_readahead when the page is dirty, not
writeback time. So this patch moves ClearPageReadahead. In v4,
ClearPageReadahead in set_page_dirty has a problem which is reported by
Steven Barrett. It's due to compound page. Some driver(ex, audio) calls
set_page_dirty with compound page which isn't on LRU. but my patch does
ClearPageRelcaim on compound page. In non-CONFIG_PAGEFLAGS_EXTENDED, it
breaks PageTail flag.
I think it doesn't affect THP and pass my test with THP enabling but Cced
Andrea for double check.
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reported-by: Steven Barrett <damentz@liquorix.net>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The rotate_reclaimable_page function moves just written out pages, which
the VM wanted to reclaim, to the end of the inactive list. That way the
VM will find those pages first next time it needs to free memory.
This patch applies the rule in memcg. It can help to prevent unnecessary
working page eviction of memcg.
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently, there are reported problem about thrashing.
(http://marc.info/?l=rsync&m=128885034930933&w=2) It happens by backup
workloads(ex, nightly rsync). That's because the workload makes just
use-once pages and touches pages twice. It promotes the page into active
list so that it results in working set page eviction.
Some app developer want to support POSIX_FADV_NOREUSE. But other OSes
don't support it, either.
(http://marc.info/?l=linux-mm&m=128928979512086&w=2)
By other approach, app developers use POSIX_FADV_DONTNEED. But it has a
problem. If kernel meets page is writing during invalidate_mapping_pages,
it can't work. It makes for application programmer to use it since they
always have to sync data before calling fadivse(..POSIX_FADV_DONTNEED) to
make sure the pages could be discardable. At last, they can't use
deferred write of kernel so that they could see performance loss.
(http://insights.oetiker.ch/linux/fadvise.html)
In fact, invalidation is very big hint to reclaimer. It means we don't
use the page any more. So let's move the writing page into inactive
list's head if we can't truncate it right now.
Why I move page to head of lru on this patch, Dirty/Writeback page would
be flushed sooner or later. It can prevent writeout of pageout which is
less effective than flusher's writeout.
Originally, I reused lru_demote of Peter with some change so added his
Signed-off-by.
Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reported-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reorder mm_struct to remove 16 bytes of alignment padding on 64 bit
builds. On my config this shrinks mm_struct by enough to fit in one
fewer cache lines and allows more objects per slab in mm_struct
kmem_cache under SLUB.
slabinfo before patch :-
Sizes (bytes) Slabs
--------------------------------
Object : 848 Total : 9
SlabObj: 896 Full : 2
SlabSiz: 16384 Partial: 5
Loss : 48 CpuSlab: 2
Align : 64 Objects: 18
slabinfo after :-
Sizes (bytes) Slabs
--------------------------------
Object : 832 Total : 7
SlabObj: 832 Full : 2
SlabSiz: 16384 Partial: 3
Loss : 0 CpuSlab: 2
Align : 64 Objects: 19
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
TestSetPageLocked() isn't being used anywhere. Also, using it would
likely be an error, since the proper interface trylock_page() provides
stronger ordering guarantees.
Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch changes the anon_vma refcount to be 0 when the object is free.
It does this by adding 1 ref to being in use in the anon_vma structure
(iow. the anon_vma->head list is not empty).
This allows a simpler release scheme without having to check both the
refcount and the list as well as avoids taking a ref for each entry on the
list.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
