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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 6D9A3C433DF for ; Thu, 4 Jun 2020 07:06:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4CA192074B for ; Thu, 4 Jun 2020 07:06:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RB3wk3qw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727769AbgFDHGP (ORCPT ); Thu, 4 Jun 2020 03:06:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726248AbgFDHGP (ORCPT ); Thu, 4 Jun 2020 03:06:15 -0400 Received: from mail-pl1-x642.google.com (mail-pl1-x642.google.com [IPv6:2607:f8b0:4864:20::642]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F2CE2C05BD1E; Thu, 4 Jun 2020 00:06:14 -0700 (PDT) Received: by mail-pl1-x642.google.com with SMTP id n2so1825404pld.13; Thu, 04 Jun 2020 00:06:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=hRfAH9I7r5GGiDIsk2j1pc8kZEvNX6DxuTqkDtLJHUQ=; b=RB3wk3qwfN1sWMD6TrolGCMoPwl22jjKGDQQ8SYmF9AEIAZ6aozPmg3q41If0I1Gy1 BeVBuNLIhYprnQhh1aV6miwBIzwbMylPgVna8qUReXS5pe4mRVUR4qXwxcsFkJDkmSYS /rArynJDUnWgP+cjvDKN7z+O3Jbm3CgmH95UuxWmBoyeZb5nFAInQBzuEOyCx7MQqMUK Wa0JOki9L4xZmZwxofC/cqOuGBa9yYP9OY+a2oZssucTtgDqX1qokCKNjXXwPvC7uECS sYYak4yV/R4D9DeMpsbjXS1x2RtCD4oDqp7zlTk6THsglD2QdOoEuFu420m+09U/xCR2 qmgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=hRfAH9I7r5GGiDIsk2j1pc8kZEvNX6DxuTqkDtLJHUQ=; b=c0Z56ZbTb/srdXyReToXwZE0CTKtA7zW9O2yMd4FdIWTYr6+nhfW1vzTGhnFS/9tvK pcfhdFVLQzSi7MEDvElu2Df+hAdVkfxvpZh50dzSqtm/V3lExfBRNgFuLjjmQl9GZLGM NPMkko/t4opkG6YYVVi7MLnw55OmmImk+5VG2SiFZUuc6OckpXWvOAxl9LIdIx8sAwml 0jvKMm30Lotc0XzuQVv1jhF/58Skdt1heuSQNNzNYtg7U/hz8IR3tRR7pEr/6nyZ02+G d1hvIc79qDjPw2ci07E/hli3YccWX0rEcJHSKHMIEBFebNiy5LfMPvRGeJ8HC1lBZCMs 40nA== X-Gm-Message-State: AOAM5333q2sW3cLjMa/S1RdkblsMLqe77EDowb7LqmIRwCe1+21X2kYe 2H/sfMJn6wbVGfyKsDRk5to= X-Google-Smtp-Source: ABdhPJzdQKyOWJFRktAaAMz26KtwsYqahRCROmSHe/mzPExXA1Sfdu5zuWZM+qXSxRIBtIUM/mJgSQ== X-Received: by 2002:a17:90a:22ad:: with SMTP id s42mr4150574pjc.200.1591254374368; Thu, 04 Jun 2020 00:06:14 -0700 (PDT) Received: from dev.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id fv7sm3350325pjb.41.2020.06.04.00.06.11 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Jun 2020 00:06:13 -0700 (PDT) From: Yafang Shao To: darrick.wong@oracle.com, david@fromorbit.com, hch@infradead.org Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Yafang Shao Subject: [PATCH v2] iomap: avoid deadlock if memory reclaim is triggered in writepage path Date: Thu, 4 Jun 2020 03:05:47 -0400 Message-Id: <1591254347-15912-1-git-send-email-laoar.shao@gmail.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Recently there is a XFS deadlock on our server with an old kernel. This deadlock is caused by allocating memory in xfs_map_blocks() while doing writeback on behalf of memroy reclaim. Although this deadlock happens on an old kernel, I think it could happen on the upstream as well. This issue only happens once and can't be reproduced, so I haven't tried to reproduce it on upsteam kernel. Bellow is the call trace of this deadlock. [480594.790087] INFO: task redis-server:16212 blocked for more than 120 seconds. [480594.790087] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [480594.790088] redis-server D ffffffff8168bd60 0 16212 14347 0x00000004 [480594.790090] ffff880da128f070 0000000000000082 ffff880f94a2eeb0 ffff880da128ffd8 [480594.790092] ffff880da128ffd8 ffff880da128ffd8 ffff880f94a2eeb0 ffff88103f9d6c40 [480594.790094] 0000000000000000 7fffffffffffffff ffff88207ffc0ee8 ffffffff8168bd60 [480594.790096] Call Trace: [480594.790101] [] schedule+0x29/0x70 [480594.790103] [] schedule_timeout+0x239/0x2c0 [480594.790111] [] io_schedule_timeout+0xae/0x130 [480594.790114] [] io_schedule+0x18/0x20 [480594.790116] [] bit_wait_io+0x11/0x50 [480594.790118] [] __wait_on_bit+0x65/0x90 [480594.790121] [] wait_on_page_bit+0x81/0xa0 [480594.790125] [] shrink_page_list+0x6d2/0xaf0 [480594.790130] [] shrink_inactive_list+0x223/0x710 [480594.790135] [] shrink_lruvec+0x3b5/0x810 [480594.790139] [] shrink_zone+0xba/0x1e0 [480594.790141] [] do_try_to_free_pages+0x100/0x510 [480594.790143] [] try_to_free_mem_cgroup_pages+0xdd/0x170 [480594.790145] [] mem_cgroup_reclaim+0x4e/0x120 [480594.790147] [] __mem_cgroup_try_charge+0x41c/0x670 [480594.790153] [] __memcg_kmem_newpage_charge+0xf6/0x180 [480594.790157] [] __alloc_pages_nodemask+0x22d/0x420 [480594.790162] [] alloc_pages_current+0xaa/0x170 [480594.790165] [] new_slab+0x30c/0x320 [480594.790168] [] ___slab_alloc+0x3ac/0x4f0 [480594.790204] [] __slab_alloc+0x40/0x5c [480594.790206] [] kmem_cache_alloc+0x193/0x1e0 [480594.790233] [] kmem_zone_alloc+0x97/0x130 [xfs] [480594.790247] [] _xfs_trans_alloc+0x3a/0xa0 [xfs] [480594.790261] [] xfs_trans_alloc+0x3c/0x50 [xfs] [480594.790276] [] xfs_iomap_write_allocate+0x1cb/0x390 [xfs] [480594.790299] [] xfs_map_blocks+0x1a6/0x210 [xfs] [480594.790312] [] xfs_do_writepage+0x17b/0x550 [xfs] [480594.790314] [] write_cache_pages+0x251/0x4d0 [xfs] [480594.790338] [] xfs_vm_writepages+0xc5/0xe0 [xfs] [480594.790341] [] do_writepages+0x1e/0x40 [480594.790343] [] __filemap_fdatawrite_range+0x65/0x80 [480594.790346] [] filemap_write_and_wait_range+0x41/0x90 [480594.790360] [] xfs_file_fsync+0x66/0x1e0 [xfs] [480594.790363] [] do_fsync+0x65/0xa0 [480594.790365] [] SyS_fdatasync+0x13/0x20 [480594.790367] [] system_call_fastpath+0x16/0x1b Note that xfs_iomap_write_allocate() is replaced by xfs_convert_blocks() in commit 4ad765edb02a ("xfs: move xfs_iomap_write_allocate to xfs_aops.c") and write_cache_pages() is replaced by iomap_writepages() in commit 598ecfbaa742 ("iomap: lift the xfs writeback code to iomap"). So for upsteam, the call trace should be, xfs_vm_writepages -> iomap_writepages -> write_cache_pages -> iomap_do_writepage -> xfs_map_blocks -> xfs_convert_blocks -> xfs_bmapi_convert_delalloc -> xfs_trans_alloc //It should alloc page with GFP_NOFS Signed-off-by: Yafang Shao --- v1 - >v2: - retile the subject from "xfs: avoid deadlock when tigger memory reclam in xfs_map_blocks()" - set GFP_NOFS in iomap_do_writepage(), per Dave. --- fs/iomap/buffered-io.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index a1ed762..f5176e3 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -17,6 +17,7 @@ #include #include #include +#include #include "trace.h" #include "../internal.h" @@ -1478,9 +1479,11 @@ static void iomap_writepage_end_bio(struct bio *bio) { struct iomap_writepage_ctx *wpc = data; struct inode *inode = page->mapping->host; + unsigned int nofs_flag; pgoff_t end_index; u64 end_offset; loff_t offset; + int ret; trace_iomap_writepage(inode, page_offset(page), PAGE_SIZE); @@ -1571,7 +1574,16 @@ static void iomap_writepage_end_bio(struct bio *bio) end_offset = offset; } - return iomap_writepage_map(wpc, wbc, inode, page, end_offset); + /* + * We can allocate memory here while doing writeback on behalf of + * memory reclaim. To avoid memory allocation deadlocks set the + * task-wide nofs context for the following operations. + */ + nofs_flag = memalloc_nofs_save(); + ret = iomap_writepage_map(wpc, wbc, inode, page, end_offset); + memalloc_nofs_restore(nofs_flag); + + return ret; redirty: redirty_page_for_writepage(wbc, page); -- 1.8.3.1