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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6DB9C433E0 for ; Tue, 12 Jan 2021 10:48:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4F07B23109 for ; Tue, 12 Jan 2021 10:48:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F07B23109 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D4A328D008F; Tue, 12 Jan 2021 05:48:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CFAED6B0289; Tue, 12 Jan 2021 05:48:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BEA1A8D008F; Tue, 12 Jan 2021 05:48:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0160.hostedemail.com [216.40.44.160]) by kanga.kvack.org (Postfix) with ESMTP id A61136B0288 for ; Tue, 12 Jan 2021 05:48:57 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 765C5180AD807 for ; Tue, 12 Jan 2021 10:48:57 +0000 (UTC) X-FDA: 77696800314.11.death39_180867327514 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 5A6B4180F8B81 for ; Tue, 12 Jan 2021 10:48:57 +0000 (UTC) X-HE-Tag: death39_180867327514 X-Filterd-Recvd-Size: 4161 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Tue, 12 Jan 2021 10:48:56 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id BAC31ADE0; Tue, 12 Jan 2021 10:48:55 +0000 (UTC) Subject: Re: [PATCH] mm, compaction: move high_pfn to the for loop scope. To: Rokudo Yan , mgorman@techsingularity.net Cc: aarcange@redhat.com, akpm@linux-foundation.org, haiwang.fu@tcl.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rientjes@google.com, tang.ding@tcl.com, xiushui.ye@tcl.com References: <20210112091041.GJ3592@techsingularity.net> <20210112094720.1238444-1-wu-yan@tcl.com> From: Vlastimil Babka Message-ID: Date: Tue, 12 Jan 2021 11:48:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210112094720.1238444-1-wu-yan@tcl.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 1/12/21 10:47 AM, Rokudo Yan wrote: > In fast_isolate_freepages, high_pfn will be used if a prefered one(PFN >= low_fn) not found. But the high_pfn > is not reset before searching an free area, so when it was used as freepage, it may from another free area searched before. > And move_freelist_head(freelist, freepage) will have unexpected behavior(eg. corrupt the MOVABLE freelist) > > Unable to handle kernel paging request at virtual address dead000000000200 > Mem abort info: > ESR = 0x96000044 > Exception class = DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > Data abort info: > ISV = 0, ISS = 0x00000044 > CM = 0, WnR = 1 > [dead000000000200] address between user and kernel address ranges > > -000|list_cut_before(inline) > -000|move_freelist_head(inline) > -000|fast_isolate_freepages(inline) > -000|isolate_freepages(inline) > -000|compaction_alloc(?, ?) > -001|unmap_and_move(inline) > -001|migrate_pages([NSD:0xFFFFFF80088CBBD0] from = 0xFFFFFF80088CBD88, [NSD:0xFFFFFF80088CBBC8] get_new_p > -002|__read_once_size(inline) > -002|static_key_count(inline) > -002|static_key_false(inline) > -002|trace_mm_compaction_migratepages(inline) > -002|compact_zone(?, [NSD:0xFFFFFF80088CBCB0] capc = 0x0) > -003|kcompactd_do_work(inline) > -003|kcompactd([X19] p = 0xFFFFFF93227FBC40) > -004|kthread([X20] _create = 0xFFFFFFE1AFB26380) > -005|ret_from_fork(asm) > ---|end of frame > > The issue was reported on an smart phone product with 6GB ram and 3GB zram as swap device. > > This patch fixes the issue by reset high_pfn before searching each free area, which ensure > freepage and freelist match when call move_freelist_head in fast_isolate_freepages(). > > Link: http://lkml.kernel.org/r/20190118175136.31341-12-mgorman@techsingularity.net > Fixes: 5a811889de10f1eb ("mm, compaction: use free lists to quickly locate a migration target") Sounds serious enough. Wonder how it wasn't reported sooner. Cc: Acked-by: Vlastimil Babka > --- > mm/compaction.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index cc1a7f600a86..75f0e550b18f 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1303,7 +1303,7 @@ fast_isolate_freepages(struct compact_control *cc) > { > unsigned int limit = min(1U, freelist_scan_limit(cc) >> 1); > unsigned int nr_scanned = 0; > - unsigned long low_pfn, min_pfn, high_pfn = 0, highest = 0; > + unsigned long low_pfn, min_pfn, highest = 0; > unsigned long nr_isolated = 0; > unsigned long distance; > struct page *page = NULL; > @@ -1348,6 +1348,7 @@ fast_isolate_freepages(struct compact_control *cc) > struct page *freepage; > unsigned long flags; > unsigned int order_scanned = 0; > + unsigned long high_pfn = 0; > > if (!area->nr_free) > continue; >