From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:47494 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751337AbdGMOJT (ORCPT ); Thu, 13 Jul 2017 10:09:19 -0400 Subject: Patch "locking/rwsem-spinlock: Fix EINTR branch in __down_write_common()" has been added to the 4.12-stable tree To: ktkhai@virtuozzo.com, a.p.zijlstra@chello.nl, gregkh@linuxfoundation.org, mingo@kernel.org, niklas.cassel@axis.com, peterz@infradead.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Thu, 13 Jul 2017 16:09:15 +0200 Message-ID: <1499954955219144@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 locking/rwsem-spinlock: Fix EINTR branch in __down_write_common() to the 4.12-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: locking-rwsem-spinlock-fix-eintr-branch-in-__down_write_common.patch and it can be found in the queue-4.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From a0c4acd2c220376b4e9690e75782d0c0afdaab9f Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Fri, 16 Jun 2017 16:44:34 +0300 Subject: locking/rwsem-spinlock: Fix EINTR branch in __down_write_common() From: Kirill Tkhai commit a0c4acd2c220376b4e9690e75782d0c0afdaab9f upstream. If a writer could been woken up, the above branch if (sem->count == 0) break; would have moved us to taking the sem. So, it's not the time to wake a writer now, and only readers are allowed now. Thus, 0 must be passed to __rwsem_do_wake(). Next, __rwsem_do_wake() wakes readers unconditionally. But we mustn't do that if the sem is owned by writer in the moment. Otherwise, writer and reader own the sem the same time, which leads to memory corruption in callers. rwsem-xadd.c does not need that, as: 1) the similar check is made lockless there, 2) in __rwsem_mark_wake::try_reader_grant we test, that sem is not owned by writer. Signed-off-by: Kirill Tkhai Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Niklas Cassel Cc: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 17fcbd590d0c "locking/rwsem: Fix down_write_killable() for CONFIG_RWSEM_GENERIC_SPINLOCK=y" Link: http://lkml.kernel.org/r/149762063282.19811.9129615532201147826.stgit@localhost.localdomain Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/locking/rwsem-spinlock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/kernel/locking/rwsem-spinlock.c +++ b/kernel/locking/rwsem-spinlock.c @@ -231,8 +231,8 @@ int __sched __down_write_common(struct r out_nolock: list_del(&waiter.list); - if (!list_empty(&sem->wait_list)) - __rwsem_do_wake(sem, 1); + if (!list_empty(&sem->wait_list) && sem->count >= 0) + __rwsem_do_wake(sem, 0); raw_spin_unlock_irqrestore(&sem->wait_lock, flags); return -EINTR; Patches currently in stable-queue which might be from ktkhai@virtuozzo.com are queue-4.12/locking-rwsem-spinlock-fix-eintr-branch-in-__down_write_common.patch