Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752367AbbHQRSw (ORCPT ); Mon, 17 Aug 2015 13:18:52 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:35533 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbbHQRSu (ORCPT ); Mon, 17 Aug 2015 13:18:50 -0400 Message-ID: <1439831928.32680.11.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: Linux 4.2-rc6 regression: RIP: e030:[] [] detach_if_pending+0x18/0x80 From: Eric Dumazet To: Sander Eikelenboom , Thomas Gleixner Cc: Jon Christopherson , David Miller , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, xen-devel@lists.xen.org, david.vrabel@citrix.com Date: Mon, 17 Aug 2015 10:18:48 -0700 In-Reply-To: <373726164.20150817162534@eikelenboom.it> References: <7c39e6332aae572372108d5fd68c503b@eikelenboom.it> <1439412094.29802.21.camel@edumazet-glaptop2.roam.corp.google.com> <0de9f30086ee2e662bdafee61d24b3c1@eikelenboom.it> <20150812.144040.1151964094247340464.davem@davemloft.net> <1439419279.29802.25.camel@edumazet-glaptop2.roam.corp.google.com> <3b284689aaa1573610c0e388e66e756a@eikelenboom.it> <1439591965.7507.6.camel@edumazet-glaptop2.roam.corp.google.com> <963062024.20150817110956@eikelenboom.it> <1439818633.7258.16.camel@edumazet-glaptop2.roam.corp.google.com> <196897465.20150817154802@eikelenboom.it> <55D1E97B.6090309@jons.org> <1439821307.7258.20.camel@edumazet-glaptop2.roam.corp.google.com> <373726164.20150817162534@eikelenboom.it> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2420 Lines: 73 From: Eric Dumazet On Mon, 2015-08-17 at 16:25 +0200, Sander Eikelenboom wrote: > Monday, August 17, 2015, 4:21:47 PM, you wrote: > > > On Mon, 2015-08-17 at 09:02 -0500, Jon Christopherson wrote: > >> This is very similar to the behavior I am seeing in this bug: > >> > >> https://bugzilla.kernel.org/show_bug.cgi?id=102911 > > > OK, but have you applied the fix ? > > > http://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=83fccfc3940c4a2db90fd7e7079f5b465cd8c6af > > > It will be part of net iteration from David Miller to Linus Torvald. > > > I did have that patch in for my last report. > But i don't think he had (looking at the second part of his oops). > Then can you try following fix as well ? Thanks ! [PATCH] timer: fix a race in __mod_timer() lock_timer_base() can not catch following : CPU1 ( in __mod_timer() timer->flags |= TIMER_MIGRATING; spin_unlock(&base->lock); base = new_base; spin_lock(&base->lock); timer->flags &= ~TIMER_BASEMASK; CPU2 (in lock_timer_base()) see timer base is cpu0 base spin_lock_irqsave(&base->lock, *flags); if (timer->flags == tf) return base; // oops, wrong base timer->flags |= base->cpu // too late We must write timer->flags in one go, otherwise we can fool other cpus. Fixes: bc7a34b8b9eb ("timer: Reduce timer migration overhead if disabled") Signed-off-by: Eric Dumazet Cc: Thomas Gleixner --- kernel/time/timer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 5e097fa9faf7..84190f02b521 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -807,8 +807,8 @@ __mod_timer(struct timer_list *timer, unsigned long expires, spin_unlock(&base->lock); base = new_base; spin_lock(&base->lock); - timer->flags &= ~TIMER_BASEMASK; - timer->flags |= base->cpu; + WRITE_ONCE(timer->flags, + (timer->flags & ~TIMER_BASEMASK) | base->cpu); } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/