tmpfs: fix highmem swapoff crash regression
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>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index dfc7069..ba4ad28 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -916,11 +916,12 @@
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: