From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59769 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752344AbcEAWPm (ORCPT ); Sun, 1 May 2016 18:15:42 -0400 Subject: Patch "asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic()" has been added to the 4.5-stable tree To: romain.perier@free-electrons.com, arnd@arndb.de, gregkh@linuxfoundation.org, peterz@infradead.org, tglx@linutronix.de, thomas.petazzoni@free-electrons.com Cc: , From: Date: Sun, 01 May 2016 15:15:41 -0700 Message-ID: <1462140941216135@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic() to the 4.5-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: asm-generic-futex-re-enable-preemption-in-futex_atomic_cmpxchg_inatomic.patch and it can be found in the queue-4.5 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From fba7cd681b6155e2d93e7862fcd6f970336b83c3 Mon Sep 17 00:00:00 2001 From: Romain Perier Date: Thu, 14 Apr 2016 15:36:03 +0200 Subject: asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic() From: Romain Perier commit fba7cd681b6155e2d93e7862fcd6f970336b83c3 upstream. The recent decoupling of pagefault disable and preempt disable added an explicit preempt_disable/enable() pair to the futex_atomic_cmpxchg_inatomic() implementation in asm-generic/futex.h. But it forgot to add preempt_enable() calls to the error handling code pathes, which results in a preemption count imbalance. This is observable on boot when the test for atomic_cmpxchg() is calling futex_atomic_cmpxchg_inatomic() on a NULL pointer. Add the missing preempt_enable() calls to the error handling code pathes. [ tglx: Massaged changelog ] Fixes: d9b9ff8c1889 ("sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly") Signed-off-by: Romain Perier Cc: linux-arch@vger.kernel.org Cc: Thomas Petazzoni Cc: Arnd Bergmann Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1460640963-690-1-git-send-email-romain.perier@free-electrons.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- include/asm-generic/futex.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -108,11 +108,15 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 val; preempt_disable(); - if (unlikely(get_user(val, uaddr) != 0)) + if (unlikely(get_user(val, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } - if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) + if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } *uval = val; preempt_enable(); Patches currently in stable-queue which might be from romain.perier@free-electrons.com are queue-4.5/asm-generic-futex-re-enable-preemption-in-futex_atomic_cmpxchg_inatomic.patch