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authorHugh Dickins <hughd@google.com>2010-08-25 23:12:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-28 13:54:12 -0700
commitf18194275c39835cb84563500995e0d503a32d9a (patch)
treeec3221ba856e6580e844c4bff200c48f2618c6ac /drivers
parentd4348c678977c7093438bbbf2067c49396ae941b (diff)
mm: fix hang on anon_vma->root->lock
After several hours, kbuild tests hang with anon_vma_prepare() spinning on a newly allocated anon_vma's lock - on a box with CONFIG_TREE_PREEMPT_RCU=y (which makes this very much more likely, but it could happen without). The ever-subtle page_lock_anon_vma() now needs a further twist: since anon_vma_prepare() and anon_vma_fork() are liable to change the ->root of a reused anon_vma structure at any moment, page_lock_anon_vma() needs to check page_mapped() again before succeeding, otherwise page_unlock_anon_vma() might address a different root->lock. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
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