Commit 9de6886e authored Sep 05, 2009 by Nicolas Pitre Committed by Linus Torvalds Sep 05, 2009

ext2: fix unbalanced kmap()/kunmap()



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>

parent ac7ac9f2

fs/ext2/namei.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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;