Commit-ID: 5ecb01cfdf96c5f465192bdb2a4fd4a61a24c6cc Gitweb: http://git.kernel.org/tip/5ecb01cfdf96c5f465192bdb2a4fd4a61a24c6cc Author: Mikael Pettersson <mikpe@xxxxxxxx> AuthorDate: Sat, 23 Jan 2010 22:36:29 +0100 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 3 Feb 2010 15:13:22 +0100 futex_lock_pi() key refcnt fix This fixes a futex key reference count bug in futex_lock_pi(), where a key's reference count is incremented twice but decremented only once, causing the backing object to not be released. If the futex is created in a temporary file in an ext3 file system, this bug causes the file's inode to become an "undead" orphan, which causes an oops from a BUG_ON() in ext3_put_super() when the file system is unmounted. glibc's test suite is known to trigger this, see <http://bugzilla.kernel.org/show_bug.cgi?id=14256>. The bug is a regression from 2.6.28-git3, namely Peter Zijlstra's 38d47c1b7075bd7ec3881141bb3629da58f88dab "[PATCH] futex: rely on get_user_pages() for shared futexes". That commit made get_futex_key() also increment the reference count of the futex key, and updated its callers to decrement the key's reference count before returning. Unfortunately the normal exit path in futex_lock_pi() wasn't corrected: the reference count is incremented by get_futex_key() and queue_lock(), but the normal exit path only decrements once, via unqueue_me_pi(). The fix is to put_futex_key() after unqueue_me_pi(), since 2.6.31 this is easily done by 'goto out_put_key' rather than 'goto out'. Signed-off-by: Mikael Pettersson <mikpe@xxxxxxxx> Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Acked-by: Darren Hart <dvhltc@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> --- kernel/futex.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index d9b3a22..1782803 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1971,7 +1971,7 @@ retry_private: /* Unqueue and drop the lock */ unqueue_me_pi(&q); - goto out; + goto out_put_key; out_unlock_put_key: queue_unlock(&q, hb); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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