From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70A36C19F28 for ; Wed, 3 Aug 2022 15:05:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237067AbiHCPFX (ORCPT ); Wed, 3 Aug 2022 11:05:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235941AbiHCPFU (ORCPT ); Wed, 3 Aug 2022 11:05:20 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25A071165 for ; Wed, 3 Aug 2022 08:05:18 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 86E26200DA; Wed, 3 Aug 2022 15:05:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1659539117; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Q2uW+G4syRD8dM4BcZV6bxX9JWzQkhNoZFr1bZzGVlE=; b=aW8NMVWo6KBt/UGogAR6L0vTRk01yBc1nh6XdOsUBFph2Iggyqty41YaUeFw4m3qx3DTfa euQYTTpIgBKUW2e+f+7mYVbZYoJQjagOH5Y437pQqwZROxmrqab9xQ8Z3/WHtJUxPm+sSm iNCQ0HgvwoH9t3ayH8Du1JPXjkGJp/w= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 66DA913AD8; Wed, 3 Aug 2022 15:05:17 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 3hlPFq2O6mLbKwAAMHmgww (envelope-from ); Wed, 03 Aug 2022 15:05:17 +0000 Date: Wed, 3 Aug 2022 17:05:16 +0200 From: Michal Hocko To: Baoquan He Cc: Christoph Hellwig , Andrew Morton , John Donnelly , David Hildenbrand , linux-mm@kvack.org, LKML Subject: Re: [PATCH] dma/pool: do not complain if DMA pool is not allocated Message-ID: References: <20220325122559.14251-1-mhocko@kernel.org> <20220325164856.GA16800@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 03-08-22 22:59:26, Baoquan He wrote: > On 08/03/22 at 11:52am, Michal Hocko wrote: > > On Fri 25-03-22 17:54:33, Michal Hocko wrote: > > > On Fri 25-03-22 17:48:56, Christoph Hellwig wrote: > > > > On Fri, Mar 25, 2022 at 01:58:42PM +0100, Michal Hocko wrote: > > > > > Dang, I have just realized that I have misread the boot log and it has > > > > > turned out that a674e48c5443 is covering my situation because the > > > > > allocation failure message says: > > > > > > > > > > Node 0 DMA free:0kB boost:0kB min:0kB low:0kB high:0kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:636kB managed:0kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB > > > > > > > > As in your report is from a kernel that does not have a674e48c5443 > > > > yet? > > > > > > yes. I just mixed up the early boot messages and thought that DMA zone > > > ended up with a single page. That message was saying something else > > > though. > > > > OK, so I have another machine spewing this warning. Still on an older > > kernel but I do not think the current upstream would be any different in > > that regards. This time the DMA zone is populated and consumed from > > large part and the pool size request is just too large for it: > > > > [ 14.017417][ T1] swapper/0: page allocation failure: order:10, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0-7 > > [ 14.017429][ T1] CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.14.21-150400.22-default #1 SLE15-SP4 0b6a6578ade2de5c4a0b916095dff44f76ef1704 > > [ 14.017434][ T1] Hardware name: XXXX > > [ 14.017437][ T1] Call Trace: > > [ 14.017444][ T1] > > [ 14.017449][ T1] dump_stack_lvl+0x45/0x57 > > [ 14.017469][ T1] warn_alloc+0xfe/0x160 > > [ 14.017490][ T1] __alloc_pages_slowpath.constprop.112+0xc27/0xc60 > > [ 14.017497][ T1] ? rdinit_setup+0x2b/0x2b > > [ 14.017509][ T1] ? rdinit_setup+0x2b/0x2b > > [ 14.017512][ T1] __alloc_pages+0x2d5/0x320 > > [ 14.017517][ T1] alloc_page_interleave+0xf/0x70 > > [ 14.017531][ T1] atomic_pool_expand+0x4a/0x200 > > [ 14.017541][ T1] ? rdinit_setup+0x2b/0x2b > > [ 14.017544][ T1] __dma_atomic_pool_init+0x44/0x90 > > [ 14.017556][ T1] dma_atomic_pool_init+0xad/0x13f > > [ 14.017560][ T1] ? __dma_atomic_pool_init+0x90/0x90 > > [ 14.017562][ T1] do_one_initcall+0x41/0x200 > > [ 14.017581][ T1] kernel_init_freeable+0x236/0x298 > > [ 14.017589][ T1] ? rest_init+0xd0/0xd0 > > [ 14.017596][ T1] kernel_init+0x16/0x120 > > [ 14.017599][ T1] ret_from_fork+0x22/0x30 > > [ 14.017604][ T1] > > [...] > > [ 14.018026][ T1] Node 0 DMA free:160kB boost:0kB min:0kB low:0kB high:0kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15996kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB > > [ 14.018035][ T1] lowmem_reserve[]: 0 0 0 0 0 > > [ 14.018339][ T1] Node 0 DMA: 0*4kB 0*8kB 0*16kB 1*32kB (U) 0*64kB 1*128kB (U) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 160kB > > > > So the DMA zone has only 160kB free while the pool would like to use 4MB > > of it which obviously fails. I haven't tried to check who is consuming > > the DMA zone memory and why but this shouldn't be all that important > > because the pool clearly cannot allocate and there is not much the > > user/admin can do about that. Well, the pool could be explicitly > > requested smaller but is that really what we expect them to do? > > > > > > > I thought there are only few pages in the managed by the DMA zone. This > > > > > is still theoretically possible so I think __GFP_NOWARN makes sense here > > > > > but it would require to change the patch description. > > > > > > > > > > Is this really worth it? > > > > > > > > In general I think for kernels where we need the pool and can't allocate > > > > it, a warning is very useful. We just shouldn't spew it when there is > > > > no need for the pool to start with. > > > > > > Well, do we have any way to find that out during early boot? > > > > Thinking about it. We should get a warning when the actual allocation > > from the pool fails no? That would be more useful information than the > > pre-allocation failure when it is not really clear whether anybody is > > ever going to consume it. > > Hi Michal, > > You haven't told on which ARCH you met this issue, is it x86_64? yes x86_64, so a small 16MB DMA zone. > If yes, I have one patch queued to fix it in another way which I have > been trying to take in mind. Any reference? -- Michal Hocko SUSE Labs