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tmpfs: fix highmem swapoff crash regression 

Commit 778dd893ae ("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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2011-05-20 15:47:33 -07:00 committed by Linus Torvalds
parent 6de06f313a
commit e6c9366b2a
1 changed files with 2 additions and 1 deletions
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3
mm/shmem.c
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@ -916,11 +916,12 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, s
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: