From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id A28676B007E for ; Fri, 4 Mar 2016 01:12:11 -0500 (EST) Received: by mail-pa0-f48.google.com with SMTP id fi3so27123098pac.3 for ; Thu, 03 Mar 2016 22:12:11 -0800 (PST) Received: from szxga03-in.huawei.com ([119.145.14.66]) by mx.google.com with ESMTPS id 2si3524126pfa.79.2016.03.03.22.12.08 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 03 Mar 2016 22:12:10 -0800 (PST) Subject: Re: Suspicious error for CMA stress test References: <56D6F008.1050600@huawei.com> <56D79284.3030009@redhat.com> <56D832BD.5080305@huawei.com> <56D887E1.8000602@redhat.com> <20160304020932.GB12036@js1304-P5Q-DELUXE> From: Hanjun Guo Message-ID: <56D92695.2040409@huawei.com> Date: Fri, 4 Mar 2016 14:09:25 +0800 MIME-Version: 1.0 In-Reply-To: <20160304020932.GB12036@js1304-P5Q-DELUXE> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim , Laura Abbott Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Andrew Morton , Sasha Levin , Laura Abbott , qiuxishi , Catalin Marinas , Will Deacon , Arnd Bergmann , "thunder.leizhen@huawei.com" , dingtinahong , chenjie6@huawei.com, "linux-mm@kvack.org" On 2016/3/4 10:09, Joonsoo Kim wrote: > On Thu, Mar 03, 2016 at 10:52:17AM -0800, Laura Abbott wrote: >> On 03/03/2016 04:49 AM, Hanjun Guo wrote: >>> On 2016/3/3 15:42, Joonsoo Kim wrote: >>>> 2016-03-03 10:25 GMT+09:00 Laura Abbott : >>>>> (cc -mm and Joonsoo Kim) >>>>> >>>>> >>>>> On 03/02/2016 05:52 AM, Hanjun Guo wrote: >>>>>> Hi, >>>>>> >>>>>> I came across a suspicious error for CMA stress test: >>>>>> >>>>>> Before the test, I got: >>>>>> -bash-4.3# cat /proc/meminfo | grep Cma >>>>>> CmaTotal: 204800 kB >>>>>> CmaFree: 195044 kB >>>>>> >>>>>> >>>>>> After running the test: >>>>>> -bash-4.3# cat /proc/meminfo | grep Cma >>>>>> CmaTotal: 204800 kB >>>>>> CmaFree: 6602584 kB >>>>>> >>>>>> So the freed CMA memory is more than total.. >>>>>> >>>>>> Also the the MemFree is more than mem total: >>>>>> >>>>>> -bash-4.3# cat /proc/meminfo >>>>>> MemTotal: 16342016 kB >>>>>> MemFree: 22367268 kB >>>>>> MemAvailable: 22370528 kB >>> [...] >>>>> I played with this a bit and can see the same problem. The sanity >>>>> check of CmaFree < CmaTotal generally triggers in >>>>> __move_zone_freepage_state in unset_migratetype_isolate. >>>>> This also seems to be present as far back as v4.0 which was the >>>>> first version to have the updated accounting from Joonsoo. >>>>> Were there known limitations with the new freepage accounting, >>>>> Joonsoo? >>>> I don't know. I also played with this and looks like there is >>>> accounting problem, however, for my case, number of free page is slightly less >>>> than total. I will take a look. >>>> >>>> Hanjun, could you tell me your malloc_size? I tested with 1 and it doesn't >>>> look like your case. >>> I tested with malloc_size with 2M, and it grows much bigger than 1M, also I >>> did some other test: >>> >>> - run with single thread with 100000 times, everything is fine. >>> >>> - I hack the cam_alloc() and free as below [1] to see if it's lock issue, with >>> the same test with 100 multi-thread, then I got: >>> >>> -bash-4.3# cat /proc/meminfo | grep Cma >>> CmaTotal: 204800 kB >>> CmaFree: 225112 kB >>> >>> It only increased about 30M for free, not 6G+ in previous test, although >>> the problem is not solved, the problem is less serious, is it a synchronization >>> problem? >>> >> 'only' 30M is still an issue although I think you are right about something related >> to synchronization. When I put the cma_mutex around free_contig_range I don't see > Hmm... I can see the issue even if putting the cma_mutex around > free_contig_range(). Yes, I can confirm that too, it can reduce the number of erronous freed memory, but the problem is still there. Thanks Hanjun -- 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