Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753966AbaFXOWZ (ORCPT ); Tue, 24 Jun 2014 10:22:25 -0400 Received: from prod-mail-xrelay07.akamai.com ([72.246.2.115]:34069 "EHLO prod-mail-xrelay07.akamai.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753248AbaFXOWX (ORCPT ); Tue, 24 Jun 2014 10:22:23 -0400 Message-ID: <53A9899C.9040005@akamai.com> Date: Tue, 24 Jun 2014 09:22:20 -0500 From: Josh Hunt User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Andrew Morton CC: "linux-kernel@vger.kernel.org" , "Baron, Jason" Subject: Re: [PATCH] panic: add TAINT_SOFTLOCKUP References: <1401847955-3345-1-git-send-email-johunt@akamai.com> <20140623151121.44f17779004e94ab620b837c@linux-foundation.org> <53A8ADEC.6070406@akamai.com> <20140623155118.e2446a6110a9889454db2386@linux-foundation.org> In-Reply-To: <20140623155118.e2446a6110a9889454db2386@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2014 05:51 PM, Andrew Morton wrote: > On Mon, 23 Jun 2014 17:45:00 -0500 Josh Hunt wrote: > >> On 06/23/2014 05:11 PM, Andrew Morton wrote: >>> On Tue, 3 Jun 2014 22:12:35 -0400 Josh Hunt wrote: >>> >>>> This taint flag will be set if the system has ever entered a softlockup >>>> state. Similar to TAINT_WARN it is useful to know whether or not the system >>>> has been in a softlockup state when debugging. >>>> >>>> ... >>>> >>>> @@ -329,6 +329,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) >>>> >>>> if (softlockup_panic) >>>> panic("softlockup: hung tasks"); >>>> + add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); >>>> __this_cpu_write(soft_watchdog_warn, true); >>>> } else >>>> __this_cpu_write(soft_watchdog_warn, false); >>> >>> Would make more sense to have applied the taint *before* calling >>> panic()? >> >> Andrew >> >> Yep, that's a good call. Thanks. Do you want me to send a v2 or did you >> take care of it? > > I fixed it up. > >> In addition to adding the softlockup taint flag, do you think it'd be >> reasonable to add another flag for page allocation failures? I think >> it'd be nice to be able to account for these conditions somehow without >> having to parse dmesg, etc. As with the softlockup flag, it's helpful to >> know if your system had encountered a page allocation failure at some >> point before the crash or whatever you're debugging. > > I don't know, really. Allocation failures are often an expected thing > as drivers try to work out how much memory they can allocate. Those > things can be screened out by testing __GFP_NOWARN. GFP_ATOMIC > failures should probably be ignored, except for when they shouldn't. > But even then, allocation failures are somewhat common. And recency is > a concern: an allocation failure 10 minutes ago is unlikely to be > relevant. > > But that's just me waving hands around. I'd be interested to hear from > people whose kernels crash more often than mine, and from those whose > job is to support them (ie distro people?). > Anyone you'd suggest adding to this thread to get other feedback about tracking page allocation failures? I could also spin up a patch and cc them. Thanks Josh -- 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/