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mm: take i_mmap_lock in unmap_mapping_range() for DAX

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DAX is not so special: we need i_mmap_lock to protect mapping->i_mmap.

__dax_pmd_fault() uses unmap_mapping_range() shoot out zero page from
all mappings.  We need to drop i_mmap_lock there to avoid lock deadlock.

Re-aquiring the lock should be fine since we check i_size after the
point.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@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:
Kirill A. Shutemov
2015-09-08 14:59:42 -07:00
committed by Linus Torvalds
parent 3fdd1b479d
commit 46c043ede4
2 changed files with 21 additions and 25 deletions
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11
mm/memory.c
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@@ -2426,17 +2426,10 @@ void unmap_mapping_range(struct address_space *mapping,
if (details.last_index < details.first_index)
details.last_index = ULONG_MAX;
/*
* DAX already holds i_mmap_lock to serialise file truncate vs
* page fault and page fault vs page fault.
*/
if (!IS_DAX(mapping->host))
i_mmap_lock_write(mapping);
i_mmap_lock_write(mapping);
if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
unmap_mapping_range_tree(&mapping->i_mmap, &details);
if (!IS_DAX(mapping->host))
i_mmap_unlock_write(mapping);
i_mmap_unlock_write(mapping);
}
EXPORT_SYMBOL(unmap_mapping_range);