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[195.135.220.15]) by mx.google.com with ESMTPS id s17si3535394edx.387.2019.04.09.05.59.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Apr 2019 05:59:55 -0700 (PDT) Received-SPF: pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 49F92AC31; Tue, 9 Apr 2019 12:59:54 +0000 (UTC) Subject: Re: [PATCH v5 2/7] slob: Respect list_head abstraction layer To: "Tobin C. Harding" , Roman Gushchin Cc: "Tobin C. Harding" , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Matthew Wilcox , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" References: <20190402230545.2929-1-tobin@kernel.org> <20190402230545.2929-3-tobin@kernel.org> <20190403180026.GC6778@tower.DHCP.thefacebook.com> <20190403211354.GC23288@eros.localdomain> From: Vlastimil Babka Message-ID: <63e395fc-41c5-00bf-0767-a313554f7b23@suse.cz> Date: Tue, 9 Apr 2019 14:59:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190403211354.GC23288@eros.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 4/3/19 11:13 PM, Tobin C. Harding wrote: > According to 0day test robot this is triggering an error from > CHECK_DATA_CORRUPTION when the kernel is built with CONFIG_DEBUG_LIST. FWIW, that report [1] was for commit 15c8410c67adef from next-20190401. I've checked and it's still the v4 version, although the report came after you submitted v5 (it wasn't testing the patches from mailing list, but mmotm). I don't see any report for the v5 version so I'd expect it to be indeed fixed by the new approach that adds boolean return parameter to slob_page_alloc(). Vlastimil [1] https://lore.kernel.org/linux-mm/5ca413c6.9TM84kwWw8lLhnmK%25lkp@intel.com/T/#u > I think this is because list_rotate_to_front() puts the list into an > invalid state before it calls __list_add(). The thing that has me > stumped is why this was not happening before this patch series was > applied? ATM I'm not able to get my test module to trigger this but I'm > going to try a bit harder today. If I'm right one solution is to modify > list_rotate_to_front() to _not_ call __list_add() but do it manually, > this solution doesn't sit well with me though. > > So, summing up, I think the patch is correct in that it does the correct > thing but I think the debugging code doesn't like it because we are > violating typical usage - so the patch is wrong :) > > thanks, > Tobin. >