From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 221516B0338 for ; Wed, 7 Jun 2017 16:56:04 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id t126so8524584pgc.9 for ; Wed, 07 Jun 2017 13:56:04 -0700 (PDT) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id y1sor2262906pli.2.2017.06.07.13.56.03 for (Google Transport Security); Wed, 07 Jun 2017 13:56:03 -0700 (PDT) Date: Wed, 7 Jun 2017 13:56:01 -0700 (PDT) From: David Rientjes Subject: Re: Sleeping BUG in khugepaged for i586 In-Reply-To: <9ab81c3c-e064-66d2-6e82-fc9bac125f56@suse.cz> Message-ID: References: <968ae9a9-5345-18ca-c7ce-d9beaf9f43b6@lwfinger.net> <20170605144401.5a7e62887b476f0732560fa0@linux-foundation.org> <1e883924-9766-4d2a-936c-7a49b337f9e2@lwfinger.net> <9ab81c3c-e064-66d2-6e82-fc9bac125f56@suse.cz> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Larry Finger , Andrew Morton , LKML , linux-mm@kvack.org On Wed, 7 Jun 2017, Vlastimil Babka wrote: > >> Hmm I'd expect such spin lock to be reported together with mmap_sem in > >> the debugging "locks held" message? > > > > My bisection of the problem is about half done. My latest good version is commit > > 7b8cd33 and the latest bad one is 2ea659a. Only about 7 steps to go. > > Hmm, your bisection will most likely just find commit 338a16ba15495 > which added the cond_resched() at mm/khugepaged.c:655. CCing David who > added it. > I agree it's probably going to bisect to 338a16ba15495 since it's the cond_resched() at the line number reported, but I think there must be something else going on. I think the list of locks held by khugepaged is correct because it matches with the implementation. The preempt_count(), as suggested by Andrew, does not. If this is reproducible, I'd like to know what preempt_count() is. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org