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Subject[001/165] tmpfs: fix highmem swapoff crash regression
2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------
Content-Length: 1204
Lines: 45
From: Hugh Dickins <hughd@google.com>

commit e6c9366b2adb52cba64b359b3050200743c7568c upstream.

Commit 778dd893ae78 ("tmpfs: fix race between umount and swapoff")
forgot the new rules for strict atomic kmap nesting, causing

WARNING: at arch/x86/mm/highmem_32.c:81

from __kunmap_atomic(), then

BUG: unable to handle kernel paging request at fffb9000

from shmem_swp_set() when shmem_unuse_inode() is handling swapoff with
highmem in use. My disgrace again.

See
https://bugzilla.kernel.org/show_bug.cgi?id=35352

Reported-by: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
mm/shmem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -916,11 +916,12 @@ static int shmem_unuse_inode(struct shme
if (size > ENTRIES_PER_PAGE)
size = ENTRIES_PER_PAGE;
offset = shmem_find_swp(entry, ptr, ptr+size);
+ shmem_swp_unmap(ptr);
if (offset >= 0) {
shmem_dir_unmap(dir);
+ ptr = shmem_swp_map(subdir);
goto found;
}
- shmem_swp_unmap(ptr);
}
}
lost1:



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