From: Al Viro Date: Thu, 12 Jun 2014 04:29:13 +0000 (-0400) Subject: lock_parent: don't step on stale ->d_parent of all-but-freed one X-Git-Tag: omap-for-v3.16/fixes-against-rc1~45^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c2338f2dc7c1e9f6202f370c64ffd7f44f3d4b51;p=pandora-kernel.git lock_parent: don't step on stale ->d_parent of all-but-freed one Dentry that had been through (or into) __dentry_kill() might be seen by shrink_dentry_list(); that's normal, it'll be taken off the shrink list and freed if __dentry_kill() has already finished. The problem is, its ->d_parent might be pointing to already freed dentry, so lock_parent() needs to be careful. We need to check that dentry hasn't already gone into __dentry_kill() *and* grab rcu_read_lock() before dropping ->d_lock - the latter makes sure that whatever we see in ->d_parent after dropping ->d_lock it won't be freed until we drop rcu_read_lock(). Signed-off-by: Al Viro --- Reading git-diff-tree failed