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 DFAD3C433EF for ; Wed, 27 Apr 2022 06:10:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E0CBB6B0078; Wed, 27 Apr 2022 02:10:41 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D703E6B007D; Wed, 27 Apr 2022 02:10:41 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A8D226B0080; Wed, 27 Apr 2022 02:10:41 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 902706B0078 for ; Wed, 27 Apr 2022 02:10:41 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 59CFA21A47 for ; Wed, 27 Apr 2022 06:10:41 +0000 (UTC) X-FDA: 79401635082.05.D1F0E47 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by imf21.hostedemail.com (Postfix) with ESMTP id 627A61C0059 for ; Wed, 27 Apr 2022 06:10:36 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R531e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xuyu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0VBRGlj2_1651039836; Received: from localhost(mailfrom:xuyu@linux.alibaba.com fp:SMTPD_---0VBRGlj2_1651039836) by smtp.aliyun-inc.com(127.0.0.1); Wed, 27 Apr 2022 14:10:36 +0800 From: Xu Yu To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, naoya.horiguchi@nec.com, shy828301@gmail.com Subject: [PATCH 2/2] mm/huge_memory: do not overkill when splitting huge_zero_page Date: Wed, 27 Apr 2022 14:10:17 +0800 Message-Id: X-Mailer: git-send-email 2.20.1.2432.ga663e714 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 627A61C0059 X-Stat-Signature: q1ndxadhn5zt55oipobm7rfi87fx6fic X-Rspam-User: Authentication-Results: imf21.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=alibaba.com; spf=pass (imf21.hostedemail.com: domain of xuyu@linux.alibaba.com designates 115.124.30.131 as permitted sender) smtp.mailfrom=xuyu@linux.alibaba.com X-HE-Tag: 1651039836-633325 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: Kernel panic when injecting memory_failure for the global huge_zero_page, when CONFIG_DEBUG_VM is enabled, as follows. Injecting memory failure for pfn 0x109ff9 at process virtual address 0x20ff9000 page:00000000fb053fc3 refcount:2 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109e00 head:00000000fb053fc3 order:9 compound_mapcount:0 compound_pincount:0 flags: 0x17fffc000010001(locked|head|node=0|zone=2|lastcpupid=0x1ffff) raw: 017fffc000010001 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000002ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(is_huge_zero_page(head)) ------------[ cut here ]------------ kernel BUG at mm/huge_memory.c:2499! invalid opcode: 0000 [#1] PREEMPT SMP PTI CPU: 6 PID: 553 Comm: split_bug Not tainted 5.18.0-rc1+ #11 Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 3288b3c 04/01/2014 RIP: 0010:split_huge_page_to_list+0x66a/0x880 Code: 84 9b fb ff ff 48 8b 7c 24 08 31 f6 e8 9f 5d 2a 00 b8 b8 02 00 00 e9 e8 fb ff ff 48 c7 c6 e8 47 3c 82 4c b RSP: 0018:ffffc90000dcbdf8 EFLAGS: 00010246 RAX: 000000000000003c RBX: 0000000000000001 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff823e4c4f RDI: 00000000ffffffff RBP: ffff88843fffdb40 R08: 0000000000000000 R09: 00000000fffeffff R10: ffffc90000dcbc48 R11: ffffffff82d68448 R12: ffffea0004278000 R13: ffffffff823c6203 R14: 0000000000109ff9 R15: ffffea000427fe40 FS: 00007fc375a26740(0000) GS:ffff88842fd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc3757c9290 CR3: 0000000102174006 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: try_to_split_thp_page+0x3a/0x130 memory_failure+0x128/0x800 madvise_inject_error.cold+0x8b/0xa1 __x64_sys_madvise+0x54/0x60 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fc3754f8bf9 Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8 RSP: 002b:00007ffeda93a1d8 EFLAGS: 00000217 ORIG_RAX: 000000000000001c RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc3754f8bf9 RDX: 0000000000000064 RSI: 0000000000003000 RDI: 0000000020ff9000 RBP: 00007ffeda93a200 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000ffffffff R11: 0000000000000217 R12: 0000000000400490 R13: 00007ffeda93a2e0 R14: 0000000000000000 R15: 0000000000000000 We think that raising BUG is overkilling for splitting huge_zero_page, the huge_zero_page can't be met from normal paths other than memory failure, but memory failure is a valid caller. So we tend to replace the BUG to WARN + returning -EBUSY, and thus the panic above won't happen again. Suggested-by: Yang Shi Cc: Naoya Horiguchi Signed-off-by: Xu Yu --- mm/huge_memory.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c468fee595ff..3bb464509518 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2496,10 +2496,12 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) int extra_pins, ret; pgoff_t end; - VM_BUG_ON_PAGE(is_huge_zero_page(head), head); VM_BUG_ON_PAGE(!PageLocked(head), head); VM_BUG_ON_PAGE(!PageCompound(head), head); + if (VM_WARN_ON_ONCE_PAGE(is_huge_zero_page(head), head)) + return -EBUSY; + if (PageWriteback(head)) return -EBUSY; -- 2.20.1.2432.ga663e714