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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 0D213C433E0 for ; Tue, 11 Aug 2020 20:49:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C38192076C for ; Tue, 11 Aug 2020 20:49:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="cS0cTNVm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C38192076C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3DE6A6B0002; Tue, 11 Aug 2020 16:49:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 390676B0005; Tue, 11 Aug 2020 16:49:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A4CB6B0006; Tue, 11 Aug 2020 16:49:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id 152176B0002 for ; Tue, 11 Aug 2020 16:49:12 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A1164181AEF07 for ; Tue, 11 Aug 2020 20:49:11 +0000 (UTC) X-FDA: 77139477702.04.flame83_1b0226226fe5 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 6E63E8007626 for ; Tue, 11 Aug 2020 20:49:11 +0000 (UTC) X-HE-Tag: flame83_1b0226226fe5 X-Filterd-Recvd-Size: 3059 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Tue, 11 Aug 2020 20:49:10 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 D693620756; Tue, 11 Aug 2020 20:49:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597178950; bh=yM/w8kXZUP5qcU80J3itZ4RsFnZNvfDi4xYYcznEv38=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cS0cTNVmGkt992d1vJ3VHy+wVjf7tezfQwBBWYEgsF0dH6psuNCda03sryMPHsQlk /kf8tmYeikxutlzIRdt8ZA3Br4iHTjyeYBdTG87dm3bYPRn4nReCSvkYE63kvV4Gef XF/8V9dnIGk7sKr6UPfiiYhHIQ+Dfg0Bbb3aoO7k= Date: Tue, 11 Aug 2020 13:49:09 -0700 From: Andrew Morton To: Eugeniu Rosca Cc: Dongli Zhang , , , Eugeniu Rosca Subject: Re: [PATCH] mm: slub: fix conversion of freelist_corrupted() Message-Id: <20200811134909.536004dcfc4c78204313dcd2@linux-foundation.org> In-Reply-To: <20200811124656.10308-1-erosca@de.adit-jv.com> References: <20200811124656.10308-1-erosca@de.adit-jv.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 6E63E8007626 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: On Tue, 11 Aug 2020 14:46:56 +0200 Eugeniu Rosca wrote: > Commit 52f23478081ae0 ("mm/slub.c: fix corrupted freechain in > deactivate_slab()") suffered an update when picked up from LKML [1]. > > Specifically, relocating 'freelist = NULL' into 'freelist_corrupted()' > created a no-op statement. Fix it by sticking to the behavior intended > in the original patch [1]. Prefer the lowest-line-count solution. > > [1] https://lore.kernel.org/linux-mm/20200331031450.12182-1-dongli.zhang@oracle.com/ > > ... > > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -677,7 +677,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct page *page, > if ((s->flags & SLAB_CONSISTENCY_CHECKS) && > !check_valid_pointer(s, page, nextfree)) { > object_err(s, page, freelist, "Freechain corrupt"); > - freelist = NULL; > slab_fix(s, "Isolate corrupted freechain"); > return true; > } > @@ -2184,8 +2183,10 @@ static void deactivate_slab(struct kmem_cache *s, struct page *page, > * 'freelist' is already corrupted. So isolate all objects > * starting at 'freelist'. > */ > - if (freelist_corrupted(s, page, freelist, nextfree)) > + if (freelist_corrupted(s, page, freelist, nextfree)) { > + freelist = NULL; > break; > + } > > do { > prior = page->freelist; Looks right. What are the runtime effects of this change? In other words, what are the end user visible effects of the present defect?