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d0e9fe1758
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Linus Torvalds d0e9fe1758 Simplify and comment on anon_vma re-use for anon_vma_prepare() 
This changes the anon_vma reuse case to require that we only reuse
simple anon_vma's - ie the case when the vma only has a single anon_vma
associated with it.

This means that a reuse of an anon_vma from an adjacent vma will always
guarantee that both vma's are associated not only with the same
anon_vma, they will also have the same anon_vma chain (of just a single
entry in this case).

And since anon_vma re-use was the only case where the same anon_vma
might be associated with different chains of anon_vma's, we now have the
case that every vma that shares the same anon_vma will always also have
the same chain.  That makes it much easier to think about merging vma's
that share the same anon_vma's: you can always just drop the other
anon_vma chain in anon_vma_merge() since you know that they are always
identical.

This also splits up the function to validate the anon_vma re-use, and
adds a lot of commentary about the possible races.

Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Borislav Petkov <bp@alien8.de> [ "That didn't fix it" ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-04-12 17:53:59 -07:00
..
backing-dev.c backing-dev: Handle class_create() failure 2010-04-02 09:46:55 +02:00
bootmem.c Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip 2010-04-07 11:02:23 -07:00
bounce.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
debug-pagealloc.c
dmapool.c dmapools: protect page_list walk in show_pools() 2009-06-30 18:56:00 -07:00
fadvise.c readahead: introduce FMODE_RANDOM for POSIX_FADV_RANDOM 2010-03-06 11:26:25 -08:00
failslab.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap_xip.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
filemap.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
fremap.c mm: clean up mm_counter 2010-03-06 11:26:23 -08:00
highmem.c grammar fix in comment 2010-02-05 12:22:40 +01:00
hugetlb.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
hwpoison-inject.c HWPOISON: Don't do early filtering if filter is disabled 2009-12-16 12:20:01 +01:00
init-mm.c
internal.h HWPOISON: add an interface to switch off/on all the page filters 2009-12-16 12:19:59 +01:00
Kconfig Merge branch 'x86-bootmem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-03-03 08:15:05 -08:00
Kconfig.debug trivial: improve help text for mm debug config options 2009-09-21 15:14:57 +02:00
kmemcheck.c kmemcheck: Fix build errors due to missing slab.h 2010-03-30 22:02:32 +09:00
kmemleak-test.c percpu: clean up percpu variable definitions 2009-06-24 15:13:48 +09:00
kmemleak.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
ksm.c mm/ksm.c is doing an unneeded _notify in write_protect_page. 2010-03-24 16:31:20 -07:00
maccess.c maccess,probe_kernel: Allow arch specific override probe_kernel_(read|write) 2010-01-07 11:58:36 -06:00
madvise.c HWPOISON: Add a madvise() injector for soft page offlining 2009-12-16 12:20:00 +01:00
Makefile percpu: don't implicitly include slab.h from percpu.h 2010-03-30 22:02:32 +09:00
memcontrol.c memcg: fix race in file_mapped accounting 2010-04-07 08:38:05 -07:00
memory_hotplug.c mm: introduce dump_page() and print symbolic flag names 2010-03-12 15:52:28 -08:00
memory-failure.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
memory.c mm: avoid null-pointer deref in sync_mm_rss() 2010-04-07 08:38:02 -07:00
mempolicy.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mempool.c mm: remove broken 'kzalloc' mempool 2009-09-22 07:17:35 -07:00
migrate.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mincore.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mlock.c mm: use rlimit helpers 2010-03-06 11:26:24 -08:00
mm_init.c
mmap.c Simplify and comment on anon_vma re-use for anon_vma_prepare() 2010-04-12 17:53:59 -07:00
mmu_context.c exit: fix oops in sync_mm_rss 2010-03-24 16:31:21 -07:00
mmu_notifier.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mmzone.c
mprotect.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
mremap.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
msync.c
nommu.c NOMMU: Fix __get_user_pages() to pin last page on offset buffers 2010-03-25 14:13:27 -07:00
oom_kill.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page_alloc.c mm: introduce dump_page() and print symbolic flag names 2010-03-12 15:52:28 -08:00
page_cgroup.c memcg: avoid use cmpxchg in swap cgroup maintainance 2010-03-17 18:43:47 -07:00
page_io.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page_isolation.c
page-writeback.c writeback: remove unused nonblocking and congestion checks 2009-12-03 13:54:25 +01:00
pagewalk.c pagemap: fix pfn calculation for hugepage 2010-04-07 08:38:04 -07:00
percpu_up.c percpu: don't implicitly include slab.h from percpu.h 2010-03-30 22:02:32 +09:00
percpu.c percpu, module: implement and use is_kernel/module_percpu_address() 2010-03-29 23:07:12 +09:00
prio_tree.c
quicklist.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
readahead.c readahead: fix NULL filp dereference 2010-04-07 08:38:03 -07:00
rmap.c rmap: fix anon_vma_fork() memory leak 2010-04-05 09:15:51 -07:00
shmem.c Fix breakage in shmem.c 2009-12-16 19:48:48 -05:00
slab.c slab: Generify kernel pointer validation 2010-04-09 10:09:50 -07:00
slob.c slab: remove duplicate kmem_cache_init_late() declarations 2009-08-06 11:36:25 +03:00
slub.c slub: Fix kmem_ptr_validate() for non-kernel pointers 2010-04-09 10:09:50 -07:00
sparse-vmemmap.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
sparse.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
swap_state.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
swap.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
swapfile.c memcg: move charges of anonymous swap 2010-03-12 15:52:36 -08:00
thrash.c mm: pass mm to grab_swap_token 2009-06-23 12:50:05 -07:00
truncate.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
util.c slab: Generify kernel pointer validation 2010-04-09 10:09:50 -07:00
vmalloc.c mm: purge fragmented percpu vmap blocks 2010-02-02 12:50:47 -08:00
vmscan.c mm: revert "vmscan: get_scan_ratio() cleanup" 2010-04-07 08:38:03 -07:00
vmstat.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00