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 CF227C433EF for ; Thu, 19 May 2022 00:58:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 08D696B0072; Wed, 18 May 2022 20:58:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 03E936B0073; Wed, 18 May 2022 20:58:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E201E6B0074; Wed, 18 May 2022 20:58:30 -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 D27D36B0072 for ; Wed, 18 May 2022 20:58:30 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id A1CC6120712 for ; Thu, 19 May 2022 00:58:30 +0000 (UTC) X-FDA: 79480681980.11.D8948FB Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf12.hostedemail.com (Postfix) with ESMTP id E84A6400BC for ; Thu, 19 May 2022 00:57:59 +0000 (UTC) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4L3Wf74Wk2zgYNG; Thu, 19 May 2022 08:57:03 +0800 (CST) Received: from dggpemm500014.china.huawei.com (7.185.36.153) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 19 May 2022 08:58:26 +0800 Received: from [10.174.178.120] (10.174.178.120) by dggpemm500014.china.huawei.com (7.185.36.153) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 19 May 2022 08:58:25 +0800 Message-ID: Date: Thu, 19 May 2022 08:58:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 To: , , , , , , , , , From: mawupeng Subject: Warning on isolate tail page in isolate_lru_page Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E84A6400BC X-Stat-Signature: ad7eez6umm9by8ztispgxncsrtq1y99e X-Rspam-User: Authentication-Results: imf12.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf12.hostedemail.com: domain of mawupeng1@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=mawupeng1@huawei.com X-HE-Tag: 1652921879-229801 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: Hi Recently I receive a warning in isolate_lru_page() reported by syzkaller. This warning occurred in linux-v5.10 and can't be be reproduced. The following two commits are the major changes since v5.10: Commit ac1e9acc5acf ("mm: rearrange madvise code to allow for reuse") refactor do_madvise in master and lead to call madvise_vma_behavior() instead of madvise_vma(). For page out these is no difference because both all them will call madvise_pageout() int the end. Commit a72afd873089 ("tlb: mmu_gather: Remove start/end arguments from tlb_gather_mmu()") remove start/end arguments from tlb_gather_mmu in madvise_pageout() since they are no longer needed. Warn msg "trying to isolate tail page" will be reported in isolate_lru_page() if this page is a tail page. However, if this page is a tail page, it will be split in madvise_cold_or_pageout_pte_range(). Read lock mmap_read_lock(mm) is hold since do_madvise() so no one can modify this. So the only reason I can image is that something is wrong in split_huge_page(). do_madvise mmap_read_lock(mm); madvise_pageout madvise_cold_or_pageout_pte_range split_huge_page(page) <-- split this huge page isolate_lru_page(page) WARN_RATELIMIT(PageTail(page), "trying to isolate tail page"); The warning log is shown below: ============================================================== WARNING: CPU: 1 PID: 26735 at mm/vmscan.c:1968 isolate_lru_page+0x44d/0x460 mm/vmscan.c:1968 Modules linked in: RAX: 06bc73006006b800 RBX: 0000000000000001 RCX: 0000000009400000 RDX: ffffc90016103000 RSI: 0000000000000344 RDI: 0000000000000345 RBP: 0000000000000001 R08: ffffffff8a58bab9 R09: ffffed100c4c4f23 R10: ffffed100c4c4f23 R11: 1ffff1100c4c4f22 R12: ffffea0001d59a00 R13: ffffea0001d59bc0 R14: ffffea0001d59bc8 R15: 0000000020ffb000 FS: 00007f00b4284700(0000) GS:ffff88811b280000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000007541ff CR3: 0000000033dec004 CR4: 00000000003706e0 Call Trace: madvise_cold_or_pageout_pte_range+0x511/0x6d0 mm/madvise.c:460 walk_pmd_range mm/pagewalk.c:89 [inline] walk_pud_range mm/pagewalk.c:160 [inline] walk_p4d_range+0x7f3/0xdb0 mm/pagewalk.c:193 walk_pgd_range+0x2d3/0x360 mm/pagewalk.c:229 __walk_page_range+0xda/0x360 mm/pagewalk.c:331 walk_page_range+0x166/0x380 mm/pagewalk.c:427 madvise_vma mm/madvise.c:520 [inline] do_madvise+0x159d/0x1810 mm/madvise.c:1137 __do_sys_madvise mm/madvise.c:1163 [inline] __se_sys_madvise mm/madvise.c:1161 [inline] __x64_sys_madvise+0x5d/0x70 mm/madvise.c:1161 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 I have no idea how to fix this warning, so is there anything else need to analysis that I haven't considered? Thanks.