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| author | Rik van Riel <riel@redhat.com> | 2010-08-09 17:18:40 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-09 20:44:55 -0700 |
| commit | 012f18004da33ba672e3c60838cc4898126174d3 (patch) | |
| tree | 990382f9f8c0d885463ac9195b8e9a18043f716d /mm/migrate.c | |
| parent | 5c341ee1dfc8fe69d66b1c8b19e463c6d7201ae1 (diff) | |
| download | linux-012f18004da33ba672e3c60838cc4898126174d3.tar.gz linux-012f18004da33ba672e3c60838cc4898126174d3.tar.bz2 linux-012f18004da33ba672e3c60838cc4898126174d3.zip | |
mm: always lock the root (oldest) anon_vma
Always (and only) lock the root (oldest) anon_vma whenever we do something
in an anon_vma. The recently introduced anon_vma scalability is due to
the rmap code scanning only the VMAs that need to be scanned. Many common
operations still took the anon_vma lock on the root anon_vma, so always
taking that lock is not expected to introduce any scalability issues.
However, always taking the same lock does mean we only need to take one
lock, which means rmap_walk on pages from any anon_vma in the vma is
excluded from occurring during an munmap, expand_stack or other operation
that needs to exclude rmap_walk and similar functions.
Also add the proper locking to vma_adjust.
Signed-off-by: Rik van Riel <riel@redhat.com>
Tested-by: Larry Woodman <lwoodman@redhat.com>
Acked-by: Larry Woodman <lwoodman@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-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>
Diffstat (limited to 'mm/migrate.c')
| -rw-r--r-- | mm/migrate.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 1855f869917d..5208fa1d9712 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -682,7 +682,7 @@ skip_unmap: rcu_unlock: /* Drop an anon_vma reference if we took one */ - if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) { + if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) { int empty = list_empty(&anon_vma->head); anon_vma_unlock(anon_vma); if (empty) |