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mm/memory-failure.c: fix spinlock vs mutex order

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We cannot take a mutex while holding a spinlock, so flip the order and
fix the locking documentation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra 2011-06-27 16:18:09 -07:00 committed by Linus Torvalds
parent aa2c96d6f3
commit 9b679320a5
2 changed files with 8 additions and 18 deletions
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21
mm/memory-failure.c
View File

@ -391,10 +391,11 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill,
struct task_struct *tsk;
struct anon_vma *av;
read_lock(&tasklist_lock);
av = page_lock_anon_vma(page);
if (av == NULL) /* Not actually mapped anymore */
goto out;
return;
read_lock(&tasklist_lock);
for_each_process (tsk) {
struct anon_vma_chain *vmac;
@ -408,9 +409,8 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill,
add_to_kill(tsk, page, vma, to_kill, tkc);
}
}
page_unlock_anon_vma(av);
out:
read_unlock(&tasklist_lock);
page_unlock_anon_vma(av);
}
/*
@ -424,17 +424,8 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
struct prio_tree_iter iter;
struct address_space *mapping = page->mapping;
/*
* A note on the locking order between the two locks.
* We don't rely on this particular order.
* If you have some other code that needs a different order
* feel free to switch them around. Or add a reverse link
* from mm_struct to task_struct, then this could be all
* done without taking tasklist_lock and looping over all tasks.
*/
read_lock(&tasklist_lock);
mutex_lock(&mapping->i_mmap_mutex);
read_lock(&tasklist_lock);
for_each_process(tsk) {
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
@ -454,8 +445,8 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
add_to_kill(tsk, page, vma, to_kill, tkc);
}
}
mutex_unlock(&mapping->i_mmap_mutex);
read_unlock(&tasklist_lock);
mutex_unlock(&mapping->i_mmap_mutex);
}
/*

5
mm/rmap.c
View File

@ -38,9 +38,8 @@
* in arch-dependent flush_dcache_mmap_lock,
* within inode_wb_list_lock in __sync_single_inode)
*
* (code doesn't rely on that order so it could be switched around)
* ->tasklist_lock
* anon_vma->mutex (memory_failure, collect_procs_anon)
* anon_vma->mutex,mapping->i_mutex (memory_failure, collect_procs_anon)
* ->tasklist_lock
* pte map lock
*/