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rmap: annotate lock context change on page_[un]lock_anon_vma()

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The page_lock_anon_vma() conditionally grabs RCU and anon_vma lock but
page_unlock_anon_vma() releases them unconditionally.  This leads sparse
to complain about context imbalance.  Annotate them.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Namhyung Kim 2010-10-26 14:22:01 -07:00 committed by Linus Torvalds
parent 1b36ba815b
commit ea4525b600
2 changed files with 17 additions and 2 deletions
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15
include/linux/rmap.h
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@ -230,7 +230,20 @@ int try_to_munlock(struct page *);
/*
* Called by memory-failure.c to kill processes.
*/
struct anon_vma *page_lock_anon_vma(struct page *page);
struct anon_vma *__page_lock_anon_vma(struct page *page);
static inline struct anon_vma *page_lock_anon_vma(struct page *page)
{
struct anon_vma *anon_vma;
__cond_lock(RCU, anon_vma = __page_lock_anon_vma(page));
/* (void) is needed to make gcc happy */
(void) __cond_lock(&anon_vma->root->lock, anon_vma);
return anon_vma;
}
void page_unlock_anon_vma(struct anon_vma *anon_vma);
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);

4
mm/rmap.c
View File

@ -314,7 +314,7 @@ void __init anon_vma_init(void)
* Getting a lock on a stable anon_vma from a page off the LRU is
* tricky: page_lock_anon_vma rely on RCU to guard against the races.
*/
struct anon_vma *page_lock_anon_vma(struct page *page)
struct anon_vma *__page_lock_anon_vma(struct page *page)
{
struct anon_vma *anon_vma, *root_anon_vma;
unsigned long anon_mapping;
@ -348,6 +348,8 @@ struct anon_vma *page_lock_anon_vma(struct page *page)
}
void page_unlock_anon_vma(struct anon_vma *anon_vma)
__releases(&anon_vma->root->lock)
__releases(RCU)
{
anon_vma_unlock(anon_vma);
rcu_read_unlock();