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ext2: fix unbalanced kmap()/kunmap()

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In ext2_rename(), dir_page is acquired through ext2_dotdot().  It is
then released through ext2_set_link() but only if old_dir != new_dir.
Failing that, the pkmap reference count is never decremented and the
page remains pinned forever.  Repeat that a couple times with highmem
pages and all pkmap slots get exhausted, and every further kmap() calls
end up stalling on the pkmap_map_wait queue at which point the whole
system comes to a halt.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nicolas Pitre 2009-09-05 00:25:37 -04:00 committed by Linus Torvalds
parent ac7ac9f2b9
commit 9de6886ec6
1 changed files with 4 additions and 0 deletions
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4
fs/ext2/namei.c
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@ -362,6 +362,10 @@ static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
if (dir_de) {
if (old_dir != new_dir)
ext2_set_link(old_inode, dir_de, dir_page, new_dir, 0);
else {
kunmap(dir_page);
page_cache_release(dir_page);
}
inode_dec_link_count(old_dir);
}
return 0;