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[2003:cb:c74e:1600:4f67:25b2:3e8c:2a4e]) by smtp.gmail.com with ESMTPSA id a4-20020a056000050400b0030ae3a6be4asm12007654wrf.72.2023.06.12.02.29.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jun 2023 02:29:19 -0700 (PDT) Message-ID: Date: Mon, 12 Jun 2023 11:29:18 +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: Andrew Morton , "zhaoyang.huang" Cc: Matthew Wilcox , Suren Baghdasaryan , Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zhaoyang Huang , 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: <20230609153519.ff01046ef0faff00a74bd5b0@linux-foundation.org> 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: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 5D478120005 X-Stat-Signature: r97eoqdeypbbdmy5bd4n7r95r4am3zsu X-Rspam-User: X-HE-Tag: 1686562165-629257 X-HE-Meta: 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 JBJXaf6V tCuNgNwQ3oGIF4/W099TEWi0rDEjzMXpkBItblXe3ynUaL2VWa+cvHNH5RRp53f0lEA0wB4gU+aPznFkomIyzUewTSfHOdEAr6O43qovR2YcN74QNl4rLqHNedvfsWWJz3lhgGf+SNlCfnYXFTMvW1ry77ChJTBV7+le6ybKnDBk/LW8feFNfQCi5TPlXwm0Pv84cKHMfC0vnLFjJQEkWWDxHDVmjm8kaDZmJIRARstezaec/bg3equTB4t5ZmU9MhcuAxMmnIjzcZS26+u5Z90r5F2lAD3Lz28XrGPRpUYJWsRkl7ibMgCGL7O4qdegj5qXYdJm1fxFj/v9Lmz+PIK+Ww6OqCi3OM2PO8YPJigDX/W4mWvjqmS2AIsS1JdiCRmumjtPPpl/cHSBuS16mZHYWmy1o9bGmZdAjmZzIg4naMMHn8o5s/k1YESHmziGVC2Pr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000100, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 ... -- Cheers, David / dhildenb