Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753221AbaFXPG0 (ORCPT ); Tue, 24 Jun 2014 11:06:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6402 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751360AbaFXPGZ (ORCPT ); Tue, 24 Jun 2014 11:06:25 -0400 Date: Tue, 24 Jun 2014 11:06:15 -0400 From: Dave Jones To: Josh Hunt Cc: Andrew Morton , "linux-kernel@vger.kernel.org" , "Baron, Jason" Subject: Re: [PATCH] panic: add TAINT_SOFTLOCKUP Message-ID: <20140624150615.GA18176@redhat.com> Mail-Followup-To: Dave Jones , Josh Hunt , Andrew Morton , "linux-kernel@vger.kernel.org" , "Baron, Jason" References: <1401847955-3345-1-git-send-email-johunt@akamai.com> <20140623151121.44f17779004e94ab620b837c@linux-foundation.org> <53A8ADEC.6070406@akamai.com> <20140623155118.e2446a6110a9889454db2386@linux-foundation.org> <53A9899C.9040005@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53A9899C.9040005@akamai.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 24, 2014 at 09:22:20AM -0500, Josh Hunt wrote: > >> 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. For things like the fuzz test runs I do, I'd have to patch this out. Things like migrate_pages() with bad arguments will trigger a page allocation failure rather easily. Likewise set_mempolicy(), and a handful of other vm syscalls. There's also the case of "too fragmented to satisfy contiguous multi-page allocation" which I walk into from time to time (when the kernel manages to survive a fuzz run long enough, which isn't that often). Dave -- 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/