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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id h19si18186954pgg.125.2019.06.03.05.11.41 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 03 Jun 2019 05:11:41 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=JOdKZZJu; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=SGbTcqGFDN+LyXFpLeZdtp0cOKIRUWh//D+jhegqSZU=; b=JOdKZZJuC3FdhIRlHcRig46fq 4ACoGuCF3Pg3JULfWngphoLmAopBT4Nlv/pE2c5+wAfB/YrOBw2Y4pxRep4elrBAFusRlgyMV/3iY P6CfMZfQOeVDry00JlZx5SHAhwLR4UQhzxQ7N2Qn9qGlf8bvi6UpQJlPe1jh8YczHVT8UDYztq+Uy psqvRrwlBMUlu7wfokylIgOwtXxsUnZA3/dZYA7JfcaXQ916SeH21BaYpu/w3naMLEzTvVGa68QNF zzQHuQ017c30jTXnb8o52oxnjcRPzYB4m5W02jJT7fjAYboRFTgQ6cWBTxaFKKQck1m5G+AeZ/4VC 6I/HQ1P8A==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hXloR-0008Tw-02; Mon, 03 Jun 2019 12:11:39 +0000 Date: Mon, 3 Jun 2019 05:11:38 -0700 From: Matthew Wilcox To: "Nagal, Amit UTC CCS" Cc: Alexander Duyck , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "CHAWLA, RITU UTC CCS" , "Netter, Christian M UTC CCS" Subject: Re: [External] Re: linux kernel page allocation failure and tuning of page cache Message-ID: <20190603121138.GC23346@bombadil.infradead.org> References: <09c5d10e9d6b4c258b22db23e7a17513@UUSALE1A.utcmail.com> <6ec47a90f5b047dabe4028ca90bb74ab@UUSALE1A.utcmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6ec47a90f5b047dabe4028ca90bb74ab@UUSALE1A.utcmail.com> User-Agent: Mutt/1.9.2 (2017-12-15) 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 Mon, Jun 03, 2019 at 05:30:57AM +0000, Nagal, Amit UTC CCS wrote: > > [ 776.174308] Mem-Info: > > [ 776.176650] active_anon:2037 inactive_anon:23 isolated_anon:0 [ > > 776.176650] active_file:2636 inactive_file:7391 isolated_file:32 [ > > 776.176650] unevictable:0 dirty:1366 writeback:1281 unstable:0 [ > > 776.176650] slab_reclaimable:719 slab_unreclaimable:724 [ > > 776.176650] mapped:1990 shmem:26 pagetables:159 bounce:0 [ > > 776.176650] free:373 free_pcp:6 free_cma:0 [ 776.209062] Node 0 > > active_anon:8148kB inactive_anon:92kB active_file:10544kB > > inactive_file:29564kB unevictable:0kB isolated(anon):0kB > > isolated(file):128kB mapped:7960kB dirty:5464kB writeback:5124kB > > shmem:104kB writeback_tmp:0kB unstable:0kB pages_scanned:0 > > all_unreclaimable? no [ 776.233602] Normal free:1492kB min:964kB > > low:1204kB high:1444kB active_anon:8148kB inactive_anon:92kB > > active_file:10544kB inactive_file:29564kB unevictable:0kB > > writepending:10588kB present:65536kB managed:59304kB mlocked:0kB > > slab_reclaimable:2876kB slab_unreclaimable:2896kB kernel_stack:1152kB > > pagetables:636kB bounce:0kB free_pcp:24kB local_pcp:24kB free_cma:0kB > > [ 776.265406] lowmem_reserve[]: 0 0 [ 776.268761] Normal: 7*4kB (H) > > 5*8kB (H) 7*16kB (H) 5*32kB (H) 6*64kB (H) 2*128kB (H) 2*256kB (H) > > 0*512kB 0*1024kB 0*2048kB 0*4096kB = 1492kB > > 10071 total pagecache pages > > [ 776.284124] 0 pages in swap cache > > [ 776.287446] Swap cache stats: add 0, delete 0, find 0/0 [ > > 776.292645] Free swap = 0kB [ 776.295532] Total swap = 0kB [ > > 776.298421] 16384 pages RAM [ 776.301224] 0 pages HighMem/MovableOnly > > [ 776.305052] 1558 pages reserved > > > > 6) we have certain questions as below : > > a) how the kernel memory got exhausted ? at the time of low memory conditions in kernel , are the kernel page flusher threads , which should have written dirty pages from page cache to flash disk , not > >executing at right time ? is the kernel page reclaim mechanism not executing at right time ? > > >I suspect the pages are likely stuck in a state of buffering. In the case of sockets the packets will get queued up until either they can be serviced or the maximum size of the receive buffer as been exceeded >and they are dropped. > > My concern here is that why the reclaim procedure has not triggered ? It has triggered. 1281 pages are under writeback.