This is a note to let you know that I've just added the patch titled
futex: Drop refcount if requeue_pi() acquired the rtmutex
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
futex-drop-refcount-if-requeue_pi-acquired-the-rtmutex.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fb75a4282d0d9a3c7c44d940582c2d226cf3acfb Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Sat, 19 Dec 2015 20:07:38 +0000
Subject: futex: Drop refcount if requeue_pi() acquired the rtmutex
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit fb75a4282d0d9a3c7c44d940582c2d226cf3acfb upstream.
If the proxy lock in the requeue loop acquires the rtmutex for a
waiter then it acquired also refcount on the pi_state related to the
futex, but the waiter side does not drop the reference count.
Add the missing free_pi_state() call.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Darren Hart <darren@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Bhuvanesh_Surachari@xxxxxxxxxx
Cc: Andy Lowe <Andy_Lowe@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20151219200607.178132067@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2494,6 +2494,11 @@ static int futex_wait_requeue_pi(u32 __u
if (q.pi_state && (q.pi_state->owner != current)) {
spin_lock(q.lock_ptr);
ret = fixup_pi_state_owner(uaddr2, &q, current);
+ /*
+ * Drop the reference to the pi state which
+ * the requeue_pi() code acquired for us.
+ */
+ free_pi_state(q.pi_state);
spin_unlock(q.lock_ptr);
}
} else {
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-3.10/x86-asm-irq-stop-relying-on-magic-jmp-behavior-for-early_idt_handlers.patch
queue-3.10/futex-drop-refcount-if-requeue_pi-acquired-the-rtmutex.patch
queue-3.10/perf-fix-inherited-events-vs.-tracepoint-filters.patch
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