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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-05-24 17:12:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-25 08:39:17 -0700
commit97a894136f29802da19a15541de3c019e1ca147e (patch)
tree1fd3f92ba92a37d5d8527a1f41458091d0a944dc /kernel/fork.c
parente4c70a6629f9c74c4b0de258a3951890e9047c82 (diff)
downloadop-kernel-dev-97a894136f29802da19a15541de3c019e1ca147e.zip
op-kernel-dev-97a894136f29802da19a15541de3c019e1ca147e.tar.gz
mm: Remove i_mmap_lock lockbreak
Hugh says: "The only significant loser, I think, would be page reclaim (when concurrent with truncation): could spin for a long time waiting for the i_mmap_mutex it expects would soon be dropped? " Counter points: - cpu contention makes the spin stop (need_resched()) - zap pages should be freeing pages at a higher rate than reclaim ever can I think the simplification of the truncate code is definitely worth it. Effectively reverts: 2aa15890f3c ("mm: prevent concurrent unmap_mapping_range() on the same inode") and takes out the code that caused its problem. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 2b44d82..4eef925 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -386,7 +386,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
spin_lock(&mapping->i_mmap_lock);
if (tmp->vm_flags & VM_SHARED)
mapping->i_mmap_writable++;
- tmp->vm_truncate_count = mpnt->vm_truncate_count;
flush_dcache_mmap_lock(mapping);
/* insert tmp into the share list, just after mpnt */
vma_prio_tree_add(tmp, mpnt);
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