Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
mm/memory-failure.c: fix spinlock vs mutex order
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>
authored by
Peter Zijlstra
and committed by
Linus Torvalds
9b679320
aa2c96d6
+8
-18
+6
-15
mm/memory-failure.c
+6
-15
mm/memory-failure.c
···
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391
struct task_struct *tsk;
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struct anon_vma *av;
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-
read_lock(&tasklist_lock);
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av = page_lock_anon_vma(page);
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if (av == NULL) /* Not actually mapped anymore */
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-
goto out;
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+
return;
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+
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+
read_lock(&tasklist_lock);
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for_each_process (tsk) {
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struct anon_vma_chain *vmac;
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···
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add_to_kill(tsk, page, vma, to_kill, tkc);
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}
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}
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-
page_unlock_anon_vma(av);
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-
out:
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read_unlock(&tasklist_lock);
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+
page_unlock_anon_vma(av);
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}
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/*
···
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struct prio_tree_iter iter;
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struct address_space *mapping = page->mapping;
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-
/*
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-
* A note on the locking order between the two locks.
429
-
* We don't rely on this particular order.
430
-
* If you have some other code that needs a different order
431
-
* feel free to switch them around. Or add a reverse link
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-
* from mm_struct to task_struct, then this could be all
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-
* done without taking tasklist_lock and looping over all tasks.
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-
*/
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-
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-
read_lock(&tasklist_lock);
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mutex_lock(&mapping->i_mmap_mutex);
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+
read_lock(&tasklist_lock);
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for_each_process(tsk) {
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430
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
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431
···
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add_to_kill(tsk, page, vma, to_kill, tkc);
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}
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}
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-
mutex_unlock(&mapping->i_mmap_mutex);
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read_unlock(&tasklist_lock);
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+
mutex_unlock(&mapping->i_mmap_mutex);
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}
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/*
+2
-3
mm/rmap.c
+2
-3
mm/rmap.c
···
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* in arch-dependent flush_dcache_mmap_lock,
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* within inode_wb_list_lock in __sync_single_inode)
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*
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-
* (code doesn't rely on that order so it could be switched around)
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-
* ->tasklist_lock
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-
* anon_vma->mutex (memory_failure, collect_procs_anon)
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+
* anon_vma->mutex,mapping->i_mutex (memory_failure, collect_procs_anon)
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+
* ->tasklist_lock
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* pte map lock
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*/
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