From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60CBCC433E2 for ; Sat, 27 Jun 2020 23:10:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 23B71204EA for ; Sat, 27 Jun 2020 23:10:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="WoDOyld9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 23B71204EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 954C06B0003; Sat, 27 Jun 2020 19:10:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9042B6B0005; Sat, 27 Jun 2020 19:10:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7F2F66B0006; Sat, 27 Jun 2020 19:10:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id 65D226B0003 for ; Sat, 27 Jun 2020 19:10:17 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 17D472C88 for ; Sat, 27 Jun 2020 23:10:17 +0000 (UTC) X-FDA: 76976537274.15.knee13_1e131e826e61 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id DCC411814B0C7 for ; Sat, 27 Jun 2020 23:10:16 +0000 (UTC) X-HE-Tag: knee13_1e131e826e61 X-Filterd-Recvd-Size: 3675 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Sat, 27 Jun 2020 23:10:16 +0000 (UTC) Received: from sol.localdomain (c-107-3-166-239.hsd1.ca.comcast.net [107.3.166.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3917820707; Sat, 27 Jun 2020 23:10:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593299415; bh=/ft0gEdXgdrpBXeR5hwd2mEJMfyWjzRx7hEcjdZ+TNk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WoDOyld9MuOVGH4iJuZ+iBHgjZH9PZxkzlfM86zFy/I0J99jZTg6FG73e9bRd11gT aPDyr/lstgl6eteNtDc09aOcMozcGW1T0F8qhIbOVL7ACUiUKzJehNz0thD1rA4uKw bVaTg0Wa/hclcMQ9rr5hV9X5IAyHZsYK9VjeO/ds= Date: Sat, 27 Jun 2020 16:10:13 -0700 From: Eric Biggers To: Qian Cai Cc: Dmitry Vyukov , syzbot , LKML , Linux-Next Mailing List , Stephen Rothwell , syzkaller-bugs , linux-mm@kvack.org Subject: Re: linux-next boot error: WARNING in kmem_cache_free Message-ID: <20200627231013.GM7065@sol.localdomain> References: <121C0D57-C9E6-406B-A280-A67E773EA9D0@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <121C0D57-C9E6-406B-A280-A67E773EA9D0@lca.pw> X-Rspamd-Queue-Id: DCC411814B0C7 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: [+Cc linux-mm; +Bcc linux-fsdevel] On Mon, Jun 22, 2020 at 03:28:09AM -0400, Qian Cai wrote: >=20 >=20 > > On Jun 22, 2020, at 2:42 AM, Dmitry Vyukov wrote= : > >=20 > > There is a reason, it's still important for us. > > But also it's not our strategy to deal with bugs by not testing > > configurations and closing eyes on bugs, right? If it's an official > > config in the kernel, it needs to be tested. If SLAB is in the state > > that we don't care about any bugs in it, then we need to drop it. It > > will automatically remove it from all testing systems out there. Or a= t > > least make it "depends on BROKEN" to slowly phase it out during > > several releases. >=20 > Do you mind sharing what=E2=80=99s your use cases with CONFIG_SLAB? The= only thing prevents it from being purged early is that it might perform = better with a certain type of networking workloads where syzbot should ha= ve nothing to gain from it. >=20 > I am more of thinking about the testing coverage that we could use for = syzbot to test SLUB instead of SLAB. Also, I have no objection for syzbot= to test SLAB, but then from my experience, you are probably on your own = to debug further with those testing failures. Until you are able to figur= e out the buggy patch or patchset introduced the regression, I am afraid = not many people would be able to spend much time on SLAB. The developers = are pretty much already half-hearted on it by only fixing SLAB here and t= here without runtime testing it. >=20 This bug also got reported 2 days later by the kernel test robot (https://lore.kernel.org/lkml/20200623090213.GW5535@shao2-debian/). Then it was fixed by commit 437edcaafbe3, so telling syzbot: #syz fix: mm, slab/slub: improve error reporting and overhead of cache_fr= om_obj()-fix If CONFIG_SLAB is no longer useful and supported then it needs to be remo= ved from the kernel. Otherwise, it needs to be tested just like all other op= tions. - Eric