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authorLinus Torvalds <torvalds@linux-foundation.org>2008-10-19 10:32:20 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-25 14:32:41 -0700
commit07a96d7019701ce9e6be9bd975e4f9d021649a8f (patch)
tree7218760bf924b272a55682c3632bc4791aaff27f /kernel/ns_cgroup.c
parent373775331502999bcf0e37e8cb06488f65482939 (diff)
anon_vma_prepare: properly lock even newly allocated entries
commit d9d332e0874f46b91d8ac4604b68ee42b8a7a2c6 upstream The anon_vma code is very subtle, and we end up doing optimistic lookups of anon_vmas under RCU in page_lock_anon_vma() with no locking. Other CPU's can also see the newly allocated entry immediately after we've exposed it by setting "vma->anon_vma" to the new value. We protect against the anon_vma being destroyed by having the SLAB marked as SLAB_DESTROY_BY_RCU, so the RCU lookup can depend on the allocation not being destroyed - but it might still be free'd and re-allocated here to a new vma. As a result, we should not do the anon_vma list ops on a newly allocated vma without proper locking. Acked-by: Nick Piggin <npiggin@suse.de> Acked-by: Hugh Dickins <hugh@veritas.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel/ns_cgroup.c')
0 files changed, 0 insertions, 0 deletions