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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5697C433EF for ; Wed, 6 Oct 2021 02:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8BCA6120F for ; Wed, 6 Oct 2021 02:43:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237322AbhJFCpH (ORCPT ); Tue, 5 Oct 2021 22:45:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45550 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237305AbhJFCox (ORCPT ); Tue, 5 Oct 2021 22:44:53 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6114CC06174E for ; Tue, 5 Oct 2021 19:43:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=wfRY/DTg/1qyRDE0hYSC9qe7NqzDHkoVCIOwsWS/Yf0=; b=Fc8ixoAHCtnfJz5qwi2JxHg4sp dl6R6HdVFEpK/fb3ZiHPCMIQB6zZGCxcqDL7X4ms0pcriSLKVmX/4X6Vvi+kNpOnD8VMtjJER3Ine MNQ7uHzHzlxLVuF/U4DZzvI7aDupBk1LKnaTe2z8tLtqdr3U2ctGqu5QTA7Q/aIFo51zkz+viiZ8D tHtvAOUMLUSjSmhzjEdYFk8AMmLoVW5zH/1pYt7mnxfqFAvK3Bz9nqTTv4O2twoB9xRoN0r1Eoxh6 L6tLvhBoXTqrKZNoIKms83SK7AAQ4inrwW5saK0feI9CY/Y1TZbc8pzJquyU04GRJzCmuoPjccW3c 0YQZd8cQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXwsW-000U2G-Pv; Wed, 06 Oct 2021 02:42:23 +0000 Date: Wed, 6 Oct 2021 03:41:56 +0100 From: Matthew Wilcox To: Rongwei Wang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, song@kernel.org, william.kucharski@oracle.com, hughd@google.com Subject: Re: [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page Message-ID: References: <20210906121200.57905-1-rongwei.wang@linux.alibaba.com> <20211006021837.59721-1-rongwei.wang@linux.alibaba.com> <20211006021837.59721-3-rongwei.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211006021837.59721-3-rongwei.wang@linux.alibaba.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 06, 2021 at 10:18:37AM +0800, Rongwei Wang wrote: > Currently collapse_file does not explicitly check PG_writeback, instead, > page_has_private and try_to_release_page are used to filter writeback > pages. This does not work for xfs with blocksize equal to or larger > than pagesize, because in such case xfs has no page->private. > > This makes collapse_file bail out early for writeback page. Otherwise, > xfs end_page_writeback will panic as follows. Could you cut the timestamps out? They don't add any value. > [ 6411.448211] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32 > [ 6411.448304] aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so" > [ 6411.448312] flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback) > [ 6411.448317] raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8 > [ 6411.448321] raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000 > [ 6411.448324] page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u)) > [ 6411.448327] page->mem_cgroup:ffff0000c3e9a000 > [ 6411.448340] ------------[ cut here ]------------ > [ 6411.448343] kernel BUG at include/linux/mm.h:1212! > [ 6411.449288] Internal error: Oops - BUG: 0 [#1] SMP > [ 6411.449786] Modules linked in: > [ 6411.449790] BUG: Bad page state in process khugepaged pfn:84ef32 > [ 6411.450143] xfs(E) > [ 6411.450459] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32 > [ 6411.451361] libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ... > [ 6411.451387] CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ... > [ 6411.451389] pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--) > [ 6411.451393] pc : end_page_writeback+0x1c0/0x214 > [ 6411.451394] lr : end_page_writeback+0x1c0/0x214 > [ 6411.451395] sp : ffff800011ce3cc0 > [ 6411.451396] x29: ffff800011ce3cc0 x28: 0000000000000000 > [ 6411.451398] x27: ffff000c04608040 x26: 0000000000000000 > [ 6411.451399] x25: ffff000c04608040 x24: 0000000000001000 > [ 6411.451401] x23: ffff0003f88c8530 x22: 0000000000001000 > [ 6411.451403] x21: ffff0003f88c8530 x20: 0000000000000000 > [ 6411.451404] x19: fffffe00201bcc80 x18: 0000000000000030 > [ 6411.451406] x17: 0000000000000000 x16: 0000000000000000 > [ 6411.451407] x15: ffff000c018f9760 x14: ffffffffffffffff > [ 6411.451409] x13: ffff8000119d72b0 x12: ffff8000119d6ee3 > [ 6411.451410] x11: ffff8000117b69b8 x10: 00000000ffff8000 > [ 6411.451412] x9 : ffff800010617534 x8 : 0000000000000000 > [ 6411.451413] x7 : ffff8000114f69b8 x6 : 000000000000000f > [ 6411.451415] x5 : 0000000000000000 x4 : 0000000000000000 > [ 6411.451416] x3 : 0000000000000400 x2 : 0000000000000000 > [ 6411.451418] x1 : 0000000000000000 x0 : 0000000000000000 > [ 6411.451420] Call trace: > [ 6411.451421] end_page_writeback+0x1c0/0x214 > [ 6411.451424] iomap_finish_page_writeback+0x13c/0x204 > [ 6411.451425] iomap_finish_ioend+0xe8/0x19c > [ 6411.451426] iomap_writepage_end_bio+0x38/0x50 > [ 6411.451427] bio_endio+0x168/0x1ec > [ 6411.451430] blk_update_request+0x278/0x3f0 > [ 6411.451432] blk_mq_end_request+0x34/0x15c > [ 6411.451435] virtblk_request_done+0x38/0x74 [virtio_blk] > [ 6411.451437] blk_done_softirq+0xc4/0x110 > [ 6411.451439] __do_softirq+0x128/0x38c > [ 6411.451441] __irq_exit_rcu+0x118/0x150 > [ 6411.451442] irq_exit+0x1c/0x30 > [ 6411.451445] __handle_domain_irq+0x8c/0xf0 > [ 6411.451446] gic_handle_irq+0x84/0x108 > [ 6411.451447] el1_irq+0xcc/0x180 > [ 6411.451448] arch_cpu_idle+0x18/0x40 > [ 6411.451450] default_idle_call+0x4c/0x1a0 > [ 6411.451453] cpuidle_idle_call+0x168/0x1e0 > [ 6411.451454] do_idle+0xb4/0x104 > [ 6411.451455] cpu_startup_entry+0x30/0x9c > [ 6411.451458] secondary_start_kernel+0x104/0x180 > [ 6411.451460] Code: d4210000 b0006161 910c8021 94013f4d (d4210000) > [ 6411.451462] ---[ end trace 4a88c6a074082f8c ]--- > [ 6411.451464] Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt > > Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs") > Suggested-by: Yang Shi > Signed-off-by: Xu Yu > Signed-off-by: Rongwei Wang Reviewed-by: Matthew Wilcox (Oracle) Although I think the Fixes: line is wrong. This bug goes all the way back to 99cb0dbd47a1.