From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by kanga.kvack.org (Postfix) with ESMTP id A75DC6B0253 for ; Wed, 4 Nov 2015 05:20:26 -0500 (EST) Received: by wikq8 with SMTP id q8so89029468wik.1 for ; Wed, 04 Nov 2015 02:20:26 -0800 (PST) Received: from mail-wm0-f49.google.com (mail-wm0-f49.google.com. [74.125.82.49]) by mx.google.com with ESMTPS id s5si836768wjs.1.2015.11.04.02.20.24 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Nov 2015 02:20:24 -0800 (PST) Received: by wmff134 with SMTP id f134so106273674wmf.1 for ; Wed, 04 Nov 2015 02:20:24 -0800 (PST) Date: Wed, 4 Nov 2015 11:20:23 +0100 From: Michal Hocko Subject: Re: [Bug 107111] New: page allocation failure but there seem to be free pages Message-ID: <20151104102023.GF29607@dhcp22.suse.cz> References: <20151103141603.261893b44e0cd6e704921fb6@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151103141603.261893b44e0cd6e704921fb6@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, bugzilla-daemon@bugzilla.kernel.org, john@calva.com, Mel Gorman On Tue 03-11-15 14:16:03, Andrew Morton wrote: [...] > > [1188431.177410] apache2: page allocation failure: order:1, mode:0x204020 > > An order-1 page, __GFP_COMP|__GFP_HIGH. ie: GFP_ATOMIC. __GFP_HIGH doesn't really work well on a small zone like DMA I am afraid. [...] > > [1188431.177521] Node 0 DMA free:7968kB min:40kB low:48kB high:60kB [...] > > [1188431.177527] lowmem_reserve[]: 0 1988 1988 1988 [...] > > [1188431.177555] Node 0 DMA: 44*4kB (UE) 94*8kB (UEM) 76*16kB (UE) 42*32kB > > (UEM) 22*64kB (UEM) 6*128kB (UE) 3*256kB (UE) 1*512kB (E) 1*1024kB (U) 0*2048kB > > 0*4096kB = 7968kB > > The DMA zone has lots and lots of higher-order pages available which > could satisfy this allocation. min = 10 - 10/2 = 5 # __GFP_HIGH min = 5 - 5/4 = 4 # ALLOC_HARDER free_pages = 1992 - ((1<<1) - 1) = 1991 free_cma = 0 1991 <= 4 + 1988 So we do not pass lowmem reserves check here... [...] > The kernel could and should have satisfied this order-1 GFP_ATOMIC > IRQ-context allocation from the DMA zone. But it did not do so. Bug. I am not really sure this is a bug to be honest. It seems that we are not coping with the non sleeping allocation pressure. I would suggest increasing min_free_kbytes. -- Michal Hocko SUSE Labs -- 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