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=-6.6 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 autolearn=unavailable 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 391C0C433DF for ; Tue, 9 Jun 2020 13:54:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F8A320737 for ; Tue, 9 Jun 2020 13:54:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AdRf2gfE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730288AbgFINyK (ORCPT ); Tue, 9 Jun 2020 09:54:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730102AbgFINyK (ORCPT ); Tue, 9 Jun 2020 09:54:10 -0400 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76571C05BD1E; Tue, 9 Jun 2020 06:54:08 -0700 (PDT) Received: by mail-io1-xd42.google.com with SMTP id r77so9834872ior.3; Tue, 09 Jun 2020 06:54:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YkLPcoh3fGm/RWXO5ci7bmyyKKN+a2YpOOHQIJQIPqY=; b=AdRf2gfE+f1rEM1qnoJGslwDtiTt0tpUMEHt5U8hWRLJ4RjbzI2IShys5vOp0MgPcJ 9srKKsBZTy9JZyGgsLOkLkXgfpJZFpY3qx5CrAEZN45964kBrg3jhHW8nMFPXefTk9bC mMI8DVbGosviwwCmh/PzGYtik2r0QOH1W+vKH/sYNjjSkpkuzrEJnZrNtqQTcT4ac76i VWjZk6Sp9M7eKSSV7+zBWkN9XMSztXe1XtoSwi+A7L7+S4b7TJ1WFaV+t/BibGNCZ/7V oyLO67XI2S3PC3mjYHxuvxU+eCFuAMW0wGO5WfTmGzDqtBzT8xASzUzLQ/bZ6rJFgF7M SHzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=YkLPcoh3fGm/RWXO5ci7bmyyKKN+a2YpOOHQIJQIPqY=; b=gIRL/7hr0SyZGXZYVzhvqXqTos7zbxngtJHOk+V8JUqbrX6P7m0PCxgDItzLesmkYh j7iPGgqPomtHCykynkiJV52AvUMzlNl1YFvTa5e/LmSjNcCBfOLuIeszYdEZTFha81ms ZLQF4ydDv2j9M84gH4Ejpr84V4XzR21h1f2Pdzg86eVhBnJBwlNZW1ai7LXAEfvI+m9D 5+1VLafnBUgS1+pwdZH1dXd16okLHchaqXHae7GeqXtrAnKVOWr342tV7NeUhVLMFyWe 9jxAfcWQpac0jzvSMeMQ7mtCDaqeD7fjAqOyIzmFu+BAkJlaeW11r+0mAJ0ky97oVdWb 95nQ== X-Gm-Message-State: AOAM533Kmbqrgb4H1noDbNSBo1OOakXbvwlZEsSV1/t3hmB+/7nUSG7B kzDd43W29JxsElsIDgbBkJLlJpySiCLxRRRnxOA= X-Google-Smtp-Source: ABdhPJwhMq/r6atG3vdj+RLpB5BNOPVBps3vee6KzFhoQutzK57aHIWn7Oqj9zN9dhhWsF/qzfblgS/EC060/C+RZjE= X-Received: by 2002:a5d:9b03:: with SMTP id y3mr26649389ion.81.1591710848254; Tue, 09 Jun 2020 06:54:08 -0700 (PDT) MIME-Version: 1.0 References: <1591254347-15912-1-git-send-email-laoar.shao@gmail.com> In-Reply-To: <1591254347-15912-1-git-send-email-laoar.shao@gmail.com> From: Yafang Shao Date: Tue, 9 Jun 2020 21:53:30 +0800 Message-ID: Subject: Re: [PATCH v2] iomap: avoid deadlock if memory reclaim is triggered in writepage path To: "Darrick J. Wong" , Dave Chinner , hch@infradead.org Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Jun 4, 2020 at 3:06 PM Yafang Shao wrote: > > 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 > Dave, Darrick, Any comments on this version ? Thanks Yafang