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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE955C433EF for ; Mon, 9 May 2022 15:39:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3CCCB6B0072; Mon, 9 May 2022 11:39:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 37D716B0073; Mon, 9 May 2022 11:39:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1F65B6B0074; Mon, 9 May 2022 11:39:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 0DEC36B0072 for ; Mon, 9 May 2022 11:39:36 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 512C6211DF for ; Mon, 9 May 2022 15:39:35 +0000 (UTC) X-FDA: 79446614310.20.5EC43F4 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) by imf09.hostedemail.com (Postfix) with ESMTP id 7BF0914003C for ; Mon, 9 May 2022 15:39:27 +0000 (UTC) Received: by mail-pl1-f175.google.com with SMTP id j14so14214265plx.3 for ; Mon, 09 May 2022 08:39:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6/chWcvBkY19DLcB+U1/TJvEN2HZbk6pQe9THfK7tl4=; b=gMhj5NAfa8kuX+GK5AoyjPHJzShaiHqMob0+aua9CPRj7Ee8B3UhTko574gd3fDCBY WTjkMgTGhp8EBzvxRKqyw4Xp8M2WnuzQVfeWaOVEu3DzyhKYX9UJcq0ulnwjFgtNHcQT CkbPfFHT4yFbfHz4GuXY0OTL+ziSVei5XMEMBESfpNBET6POcbE8J6tttv+POmRsntNq YWpBaDHfbJXD4CtdLgievqMEJ+RsvrUpAWxTUpwRJ89SH2sdWGDL5vLd1B+gkx/l5U0Y Dw2vkgJjuBBOO+IBNjw+mkS+/CEZClL9qiAzhUNUELqit8LIQFYGO7J6ofW0LN/eY76L TY/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=6/chWcvBkY19DLcB+U1/TJvEN2HZbk6pQe9THfK7tl4=; b=iZX//aAzXNuwCOBpkDTWD6u8ZXiFwd5o9lvBivduZn5jVuxbuvwT9vmuPaAGGcgYY9 9k7upk02R6WGzwqUL7vMB1mHdqRopbIDxBmzNXhNTewom/I02P/G3hH1/KxS+x9xrRvf 4sVisgH4xU4buqOv/YIF4r+NOzaJj2AlJFZFF3MEgYs+a/xdlSPr/rfKgUPvb6btJJ9B Cv11EAsGpgJHSKTBBJGqKFCuLV5ezqbf9MxhZsrUWXKllJ0kN9AoNPf8G+rROZQ0rM5z lroOnmD+mU58/QLS7g3SRfd0bIguI9XZKJxfM5cp63yd4uQyIxvNvoJQwDf7xqinz7UM Tq/w== X-Gm-Message-State: AOAM530kdrwv7vtOWVoiEtttSmjnkF2Xakz4HLIGo/DSt/eClTyWBlh1 GTakx2tZg5S7Rr2Az37ci3k= X-Google-Smtp-Source: ABdhPJzZaiuoQoQ8UtW7Pp2JgsA9jZZFz6hG+13CXjxTRjIbJEXPje+mOJuzda3Qn1p3WPHjZNmm9Q== X-Received: by 2002:a17:902:a407:b0:15d:29cc:5f56 with SMTP id p7-20020a170902a40700b0015d29cc5f56mr17206972plq.132.1652110773644; Mon, 09 May 2022 08:39:33 -0700 (PDT) Received: from google.com ([2620:15c:211:201:3704:694b:acc0:e064]) by smtp.gmail.com with ESMTPSA id 5-20020a630705000000b003c14af5061esm8605388pgh.54.2022.05.09.08.39.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 May 2022 08:39:33 -0700 (PDT) Date: Mon, 9 May 2022 08:39:31 -0700 From: Minchan Kim To: Dong Aisheng Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dongas86@gmail.com, linux-imx@nxp.com, akpm@linux-foundation.org, m.szyprowski@samsung.com, lecopzer.chen@mediatek.com, david@redhat.com, vbabka@suse.cz, stable@vger.kernel.org Subject: Re: [PATCH 1/1] Revert "mm/cma.c: remove redundant cma_mutex lock" Message-ID: References: <20220509094551.3596244-1-aisheng.dong@nxp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220509094551.3596244-1-aisheng.dong@nxp.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7BF0914003C X-Stat-Signature: aeqxqxb6uqebh5ott4ngkz9mj51bnz5k X-Rspam-User: Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=gMhj5NAf; spf=pass (imf09.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.214.175 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-HE-Tag: 1652110767-44138 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, May 09, 2022 at 05:45:51PM +0800, Dong Aisheng wrote: > This reverts commit a4efc174b382fcdb62e2d90d39e78a274a975e38 which > introduced a regression issue that when there're multiple processes > allocating dma memory in parallel by calling dma_alloc_coherent(), it > may fail sometimes as follows: > > Error log: > cma: cma_alloc: linux,cma: alloc failed, req-size: 148 pages, ret: -16 > cma: number of available pages: > 3@125+20@172+12@236+4@380+32@736+17@2287+23@2473+20@36076+99@40477+108@40852+44@41108+20@41196+108@41364+108@41620+ > 108@42900+108@43156+483@44061+1763@45341+1440@47712+20@49324+20@49388+5076@49452+2304@55040+35@58141+20@58220+20@58284+ > 7188@58348+84@66220+7276@66452+227@74525+6371@75549=> 33161 free of 81920 total pages > > When issue happened, we saw there were still 33161 pages (129M) free CMA > memory and a lot available free slots for 148 pages in CMA bitmap that we > want to allocate. > > When dumping memory info, we found that there was also ~342M normal memory, > but only 1352K CMA memory left in buddy system while a lot of pageblocks > were isolated. > > Memory info log: > Normal free:351096kB min:30000kB low:37500kB high:45000kB reserved_highatomic:0KB > active_anon:98060kB inactive_anon:98948kB active_file:60864kB inactive_file:31776kB > unevictable:0kB writepending:0kB present:1048576kB managed:1018328kB mlocked:0kB > bounce:0kB free_pcp:220kB local_pcp:192kB free_cma:1352kB lowmem_reserve[]: 0 0 0 > Normal: 78*4kB (UECI) 1772*8kB (UMECI) 1335*16kB (UMECI) 360*32kB (UMECI) 65*64kB (UMCI) > 36*128kB (UMECI) 16*256kB (UMCI) 6*512kB (EI) 8*1024kB (UEI) 4*2048kB (MI) 8*4096kB (EI) > 8*8192kB (UI) 3*16384kB (EI) 8*32768kB (M) = 489288kB > > The root cause of this issue is that since commit a4efc174b382 > ("mm/cma.c: remove redundant cma_mutex lock"), CMA supports concurrent > memory allocation. It's possible that the memory range process A trying > to alloc has already been isolated by the allocation of process B during > memory migration. > > The problem here is that the memory range isolated during one allocation > by start_isolate_page_range() could be much bigger than the real size we > want to alloc due to the range is aligned to MAX_ORDER_NR_PAGES. > > Taking an ARMv7 platform with 1G memory as an example, when MAX_ORDER_NR_PAGES > is big (e.g. 32M with max_order 14) and CMA memory is relatively small > (e.g. 128M), there're only 4 MAX_ORDER slot, then it's very easy that > all CMA memory may have already been isolated by other processes when > one trying to allocate memory using dma_alloc_coherent(). > Since current CMA code will only scan one time of whole available CMA > memory, then dma_alloc_coherent() may easy fail due to contention with > other processes. > > This patch simply falls back to the original method that using cma_mutex > to make alloc_contig_range() run sequentially to avoid the issue. > Link: https://lore.kernel.org/all/20220315144521.3810298-2-aisheng.dong@nxp.com/ Adding a link would be helpful why decided to revert. > Cc: Andrew Morton > Cc: Marek Szyprowski > Cc: Lecopzer Chen > Cc: David Hildenbrand > Cc: Vlastimil Babka > Cc: Minchan Kim > CC: stable@vger.kernel.org # 5.11+ > Fixes: a4efc174b382 ("mm/cma.c: remove redundant cma_mutex lock") > Signed-off-by: Dong Aisheng Acked-by: Minchan Kim