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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 171DAC433DF for ; Fri, 7 Aug 2020 19:06:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C1CD7206B5 for ; Fri, 7 Aug 2020 19:06:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FWbrx8uq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C1CD7206B5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4D50E8D0003; Fri, 7 Aug 2020 15:06:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 484FC6B000D; Fri, 7 Aug 2020 15:06:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 39AC08D0003; Fri, 7 Aug 2020 15:06:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id 23C116B000C for ; Fri, 7 Aug 2020 15:06:40 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C9A89180AD802 for ; Fri, 7 Aug 2020 19:06:39 +0000 (UTC) X-FDA: 77124704118.24.skin25_311367826fc2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 91D121A4AA for ; Fri, 7 Aug 2020 19:06:39 +0000 (UTC) X-HE-Tag: skin25_311367826fc2 X-Filterd-Recvd-Size: 4134 Received: from mail-ot1-f65.google.com (mail-ot1-f65.google.com [209.85.210.65]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Fri, 7 Aug 2020 19:06:39 +0000 (UTC) Received: by mail-ot1-f65.google.com with SMTP id e11so2417120otk.4 for ; Fri, 07 Aug 2020 12:06:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=zLv6z3MDMuVW61EC2fkzzHGi8++0GERRj/VmpMRNPpc=; b=FWbrx8uquzQVwqJv5hztOcbzXrnTCu9fqAAQ0IE1v+p9MlOGSWbUWhYbsm8hLaWK2m nQERO7jZSxSbFWWq5x4hgtMrGSVsEy09I7bwf1toeXEFZiEjBh+d9DfLBeNeFZMUjqyP d574AxHUn09Uvdm/XkzOb0pWhuP5oWkbtNRwfvw/33f74BZMLenW4ARUZKdAXL842Tjx BMk1sXYx071o9L0oAedbxZo1UrA3p1vbjHXiKAeLFeHjILX6Nz6Mshjh4iQcxNxlDmRG 86F8KMhoX9f88cK29/CD3rrlo7kLHZ0xBJ7zlOv6LvifqvHhCeyBH1A+lXFaw9agT9sK MYJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zLv6z3MDMuVW61EC2fkzzHGi8++0GERRj/VmpMRNPpc=; b=RUCIGXz1Fz9sXPom616gMHpYhx+CQK+K9q/rqVyePALK0VS1GxM5+SFGDXH4nbXRuX d/+8WunW+GX4gUtD+hw0n7L0CfC1gwD9+FRLJ6wpsiQxDQnnqPGhLLLVRzWjid9IlJH7 bvIPAk91r63S6aZxHq1Mvzp+cB39hHwHXPemWvlKOlDoPrNIEkVlt4EahCsjfIh2k9c+ dmAP6pk1bUOCPE8sB05OVa6gIr97DPzh/MX5OgaNjhdyvqa4Nw46KBhpQhWMAAge8GWL rSU3br0jIPrfIfIxUuKcNxQ+49LEY1uxZ0Xe/7wyCp9PL25dnaufeHhlureuwG5XUFO3 PR8w== X-Gm-Message-State: AOAM533+lN+UikEWyu/XSIQLVDJbqJ5tG6BkqACo+8nzWiXzUNypc6en SWOOZBjU/bCiMTzaQgYdOBNKKIZ6AwEeVDAAPVU= X-Google-Smtp-Source: ABdhPJwVJolOgJnLC9C2Rvy+MXOAFNwhTJiYKp2dL8jZ6mb7DyR3pYfGGW6b78hgfsbsIM705UNA1tVhZ20cEUAUBUE= X-Received: by 2002:a9d:3d77:: with SMTP id a110mr13124283otc.11.1596827198586; Fri, 07 Aug 2020 12:06:38 -0700 (PDT) MIME-Version: 1.0 References: <20200807160627.GA1420741@elver.google.com> <20200807171849.GA1467156@elver.google.com> In-Reply-To: <20200807171849.GA1467156@elver.google.com> From: Pekka Enberg Date: Fri, 7 Aug 2020 22:06:22 +0300 Message-ID: Subject: Re: Odd-sized kmem_cache_alloc and slub_debug=Z To: Marco Elver Cc: Alexander Potapenko , Andrew Morton , David Rientjes , Joonsoo Kim , Christoph Lameter , Kees Cook , kasan-dev@googlegroups.com, LKML , "linux-mm@kvack.org" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 91D121A4AA X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: Hi Marco and Kees, On Fri, Aug 07, 2020 at 08:06PM +0300, Pekka Enberg wrote: > > Anything interesting in your .config? The fault does not reproduce > > with 5.8.0 + x86-64 defconfig. On Fri, Aug 7, 2020 at 8:18 PM Marco Elver wrote: > It's quite close to defconfig, just some extra options for my test > environment. But none that I'd imagine change this behaviour -- but > maybe I missed something. I've attached my config. Also, just in case, > I'm on mainline from Tuesday: 2324d50d051ec0f14a548e78554fb02513d6dcef. Yeah, it reproduces with defconfig too, as long as you remember to pass "slub_debug=Z"... :-/ The following seems to be the culprit: commit 3202fa62fb43087387c65bfa9c100feffac74aa6 Author: Kees Cook Date: Wed Apr 1 21:04:27 2020 -0700 slub: relocate freelist pointer to middle of object Reverting this commit and one of it's follow up fixes from Kees from v5.8 makes the issue go away for me. Btw, please note that caches with size 24 and larger do not trigger this bug, so the issue is that with small enough object size, we're stomping on allocator metadata (I assume part of the freelist). - Pekka