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=-8.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 56FC3CA9ECF for ; Fri, 1 Nov 2019 18:32:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1C97A21855 for ; Fri, 1 Nov 2019 18:32:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C97A21855 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A72AC6B0008; Fri, 1 Nov 2019 14:32:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A234D6B000A; Fri, 1 Nov 2019 14:32:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9391E6B000C; Fri, 1 Nov 2019 14:32:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0019.hostedemail.com [216.40.44.19]) by kanga.kvack.org (Postfix) with ESMTP id 7D6C36B0008 for ; Fri, 1 Nov 2019 14:32:24 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 1E57F75AA for ; Fri, 1 Nov 2019 18:32:24 +0000 (UTC) X-FDA: 76108553808.24.month40_14e5dd9c94612 X-HE-Tag: month40_14e5dd9c94612 X-Filterd-Recvd-Size: 5586 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Fri, 1 Nov 2019 18:32:23 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id EAB12B3B8; Fri, 1 Nov 2019 18:32:21 +0000 (UTC) Date: Fri, 1 Nov 2019 19:32:20 +0100 From: Michal Hocko To: zhong jiang Cc: akpm@linux-foundation.org, minchan@kernel.org, hannes@cmpxchg.org, linux-mm@kvack.org Subject: Re: [PATCH v3] mm: fix trying to reclaim unevictable lru page when calling madvise_pageout Message-ID: <20191101183220.GC29196@dhcp22.suse.cz> References: <1572616245-18946-1-git-send-email-zhongjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1572616245-18946-1-git-send-email-zhongjiang@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Fri 01-11-19 21:50:45, zhong jiang wrote: > Recently, I hit the following issue when running in the upstream. > > kernel BUG at mm/vmscan.c:1521! > invalid opcode: 0000 [#1] SMP KASAN PTI > CPU: 0 PID: 23385 Comm: syz-executor.6 Not tainted 5.4.0-rc4+ #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 > RIP: 0010:shrink_page_list+0x12b6/0x3530 mm/vmscan.c:1521 > Code: de f5 ff ff e8 ab 79 eb ff 4c 89 f7 e8 43 33 0d 00 e9 cc f5 ff ff e8 99 79 eb ff 48 c7 c6 a0 34 2b a0 4c 89 f7 e8 1a 4d 05 00 <0f> 0b e8 83 79 eb ff 48 89 d8 48 c1 e8 03 42 80 3c 38 00 0f 85 74 > RSP: 0018:ffff88819a3df5a0 EFLAGS: 00010286 > RAX: 0000000000040000 RBX: ffffea00061c3980 RCX: ffffffff814fba36 > RDX: 00000000000056f7 RSI: ffffc9000c02c000 RDI: ffff8881f70268cc > RBP: ffff88819a3df898 R08: ffffed103ee05de0 R09: ffffed103ee05de0 > R10: 0000000000000001 R11: ffffed103ee05ddf R12: ffff88819a3df6f0 > R13: ffff88819a3df6f0 R14: ffffea00061c3980 R15: dffffc0000000000 > FS: 00007f21b9d8e700(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000001b2d621000 CR3: 00000001c8c46004 CR4: 00000000007606f0 > DR0: 0000000020000140 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 > PKRU: 55555554 > Call Trace: > reclaim_pages+0x499/0x800 mm/vmscan.c:2188 > madvise_cold_or_pageout_pte_range+0x58a/0x710 mm/madvise.c:453 > walk_pmd_range mm/pagewalk.c:53 [inline] > walk_pud_range mm/pagewalk.c:112 [inline] > walk_p4d_range mm/pagewalk.c:139 [inline] > walk_pgd_range mm/pagewalk.c:166 [inline] > __walk_page_range+0x45a/0xc20 mm/pagewalk.c:261 > walk_page_range+0x179/0x310 mm/pagewalk.c:349 > madvise_pageout_page_range mm/madvise.c:506 [inline] > madvise_pageout+0x1f0/0x330 mm/madvise.c:542 > madvise_vma mm/madvise.c:931 [inline] > __do_sys_madvise+0x7d2/0x1600 mm/madvise.c:1113 > do_syscall_64+0x9f/0x4c0 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > madvise_pageout access the specified range of the vma and isolate > them, then run shrink_page_list to reclaim its memory. But It also > isolate the unevictable page to reclaim. Hence, we can catch the > cases in shrink_page_list. > > The root cause is that we scan the page tables instead of specific > LRU list. and so we need to filter out the unevictable lru pages > from our end. > > Fixes: 1a4e58cce84e ("mm: introduce MADV_PAGEOUT") > Cc: stable@vger.kernel.org > Suggested-by: Johannes Weiner > Signed-off-by: zhong jiang Acked-by: Michal Hocko But I would really appreciate to add a comment for the BUG_ON and explain why do we care about PageUnevictable so much when there is an explicit page_evictable check in the reclaim path. In other words a short summary of what Johannes explained in http://lkml.kernel.org/r/20191030193307.GA48128@cmpxchg.org. Maybe in a separate patch. Care to send one or should I send it? > --- > v2 -> v3: > Modified the mail address to hannes@cmpxchg.org > > v1 -> v2: > Remove BUG_ON is not an good solutions. Becuase it indeed can > see !page_evictable() in shrink_page_list due to some race. > > mm/madvise.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 99dd06f..63e1308 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -363,8 +363,12 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > ClearPageReferenced(page); > test_and_clear_page_young(page); > if (pageout) { > - if (!isolate_lru_page(page)) > - list_add(&page->lru, &page_list); > + if (!isolate_lru_page(page)) { > + if (PageUnevictable(page)) > + putback_lru_page(page); > + else > + list_add(&page->lru, &page_list); > + } > } else > deactivate_page(page); > huge_unlock: > @@ -441,8 +445,12 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, > ClearPageReferenced(page); > test_and_clear_page_young(page); > if (pageout) { > - if (!isolate_lru_page(page)) > - list_add(&page->lru, &page_list); > + if (!isolate_lru_page(page)) { > + if (PageUnevictable(page)) > + putback_lru_page(page); > + else > + list_add(&page->lru, &page_list); > + } > } else > deactivate_page(page); > } > -- > 1.7.12.4 -- Michal Hocko SUSE Labs