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[2003:cb:c74e:1600:4f67:25b2:3e8c:2a4e]) by smtp.gmail.com with ESMTPSA id n16-20020adfe350000000b0030e5b1fffc3sm12031233wrj.9.2023.06.12.03.01.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jun 2023 03:01:21 -0700 (PDT) Message-ID: Date: Mon, 12 Jun 2023 12:01:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCHv5] mm: skip CMA pages when they are not available To: Zhaoyang Huang Cc: Andrew Morton , "zhaoyang.huang" , Matthew Wilcox , Suren Baghdasaryan , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, ke.wang@unisoc.com References: <1685501461-19290-1-git-send-email-zhaoyang.huang@unisoc.com> <20230609153519.ff01046ef0faff00a74bd5b0@linux-foundation.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 0BBFA1C0022 X-Rspam-User: X-Stat-Signature: 4pes1y541gb7zw4kf4fbkjwahz9hndgo X-Rspamd-Server: rspam03 X-HE-Tag: 1686564085-871551 X-HE-Meta: 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 K8tz/k7E dgQUEVd4YCwYsxq92aNn56J2bIOpOSisj2TGNHg0kQ1Udw0b6UelcrJqYwNoZ7Y+lQeQU5QThHqVHdtz23x7fwwVH1znjT0Dd7HgxwC9Nz565fW+/ji4y6BY30lTEWBgSPXoAPnbo23Ukp8vBYHADs1x22UYFwzKLrGeifCGorzAR+pHw5/fX+DwOWGECaAiXuOMr8tAnVW/yx0SYra2HM2zEuF17VMti3YoTlG6ln/1dfpfPuSWKqmSdb26Pu8UhOcyaEvPes2eK7janwypdcod79KTxRht32o6e/2BDc0UOuNQ4/nKKu8pE2tKTKqLtnl5P+2qr0EaOlhSKTDxoqyRl7qP847CKT2BkwMsxA9dwcvgbL99onNn/iqMXGZfb+9ubeHJNoQ+DqBkbF/JGsL0MX0pyh8xo//cC2qcQ+nItaQJdLgiQX2JXf9+h7dYS4b/6TlA3ZZtvS3aX+j+obDtHZWyyV1ndmFBezZqedMBqz/oqDUYXtYKSHvBOz9ehV1Wek3MU6+pdMojiIKZuLJKUkQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000019, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12.06.23 11:35, Zhaoyang Huang wrote: > On Mon, Jun 12, 2023 at 5:29 PM David Hildenbrand wrote: >> >> On 10.06.23 00:35, Andrew Morton wrote: >>> On Wed, 31 May 2023 10:51:01 +0800 "zhaoyang.huang" wrote: >>> >>>> From: Zhaoyang Huang >>>> >>>> This patch fixes unproductive reclaiming of CMA pages by skipping them when they >>>> are not available for current context. It is arise from bellowing OOM issue, which >>>> caused by large proportion of MIGRATE_CMA pages among free pages. >>>> >>>> [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 >>>> [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB >>>> [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB >>>> ... >>>> [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) >>>> [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 >>>> [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 >>>> >>> >>> We saw plenty of feedback for earlier versions, but now silence. Does >>> this mean we're all OK with v5? >> >> The logic kind-of makes sense to me (but the kswapd special-casing >> already shows that it might be a bit fragile for future use), but I did >> not yet figure out if this actually fixes something or is a pure >> performance improvement. >> >> As we phrased it in the comment "It is waste of effort", but in the >> patch description "This patch fixes unproductive reclaiming" + a scary >> dmesg. >> >> Am I correct that this is a pure performance optimization (and the issue >> revealed itself in that OOM report), or does this actually *fix* something? >> >> If it's a performance improvement, it would be good to show that it is >> an actual improvement worth the churn ... > Sorry for the confusion. As for the OOM issue, the previous > commit(https://lkml.kernel.org/r/1683782550-25799-1-git-send-email-zhaoyang.huang@unisoc.com) > helps to decrease the fail rate from 12/20 to 2/20, which it turn to > be 0 when applying this patch. Thanks! Can we make that clearer in the patch description? I'm struggling a bit my self to find the right words. Something like "This change further decreases the chance for wrong OOMs in the presence of a lot of CMA memory." ? In any case Acked-by: David Hildenbrand -- Cheers, David / dhildenb