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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 88EB3C55186 for ; Wed, 22 Apr 2020 10:12:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DE902070B for ; Wed, 22 Apr 2020 10:12:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587550337; bh=hXcckUw8SWYVjxzLptV0zh/8I4jsnpWi6/p0ftXNo/c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nPMEeKpuGuByDA+c8CCP4WV1lTFBKHQdR+z4O3/qFUL+hwqERIEBXufCCuLu9dL3R u+nz5taxGgiaDyuwddXT8n3yq1JvrPELOcinaWtMSQo88N8VIFWxvBnQiMfitb9Okf ZWlNYifg59B2dHJZF/Z53bX4Nbj9TxKk9WhIyOJ0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728029AbgDVKMQ (ORCPT ); Wed, 22 Apr 2020 06:12:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:44696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729279AbgDVKMB (ORCPT ); Wed, 22 Apr 2020 06:12:01 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A427320575; Wed, 22 Apr 2020 10:11:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587550320; bh=hXcckUw8SWYVjxzLptV0zh/8I4jsnpWi6/p0ftXNo/c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a6mzPUhoeXaCTuv4DqGPIs6nLPV4zdLP7OBgRYr8SiYciNL0G3iHa37+5P+avFoZp SSnuK5wh8E+3wqMAuv3gWteaVaNpoZ7rcoQe0QKEnUA9TJ172PsTRRNPQw41kYRWIC i7Dz7/StK+O9lH2n0dgzhPD5KH/sGZzeQn7DwQIo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , David Sterba , Sasha Levin Subject: [PATCH 4.14 096/199] btrfs: use nofs allocations for running delayed items Date: Wed, 22 Apr 2020 11:57:02 +0200 Message-Id: <20200422095107.617901922@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095057.806111593@linuxfoundation.org> References: <20200422095057.806111593@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Josef Bacik [ Upstream commit 351cbf6e4410e7ece05e35d0a07320538f2418b4 ] Zygo reported the following lockdep splat while testing the balance patches ====================================================== WARNING: possible circular locking dependency detected 5.6.0-c6f0579d496a+ #53 Not tainted ------------------------------------------------------ kswapd0/1133 is trying to acquire lock: ffff888092f622c0 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node+0x7c/0x5b0 but task is already holding lock: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}: fs_reclaim_acquire.part.91+0x29/0x30 fs_reclaim_acquire+0x19/0x20 kmem_cache_alloc_trace+0x32/0x740 add_block_entry+0x45/0x260 btrfs_ref_tree_mod+0x6e2/0x8b0 btrfs_alloc_tree_block+0x789/0x880 alloc_tree_block_no_bg_flush+0xc6/0xf0 __btrfs_cow_block+0x270/0x940 btrfs_cow_block+0x1ba/0x3a0 btrfs_search_slot+0x999/0x1030 btrfs_insert_empty_items+0x81/0xe0 btrfs_insert_delayed_items+0x128/0x7d0 __btrfs_run_delayed_items+0xf4/0x2a0 btrfs_run_delayed_items+0x13/0x20 btrfs_commit_transaction+0x5cc/0x1390 insert_balance_item.isra.39+0x6b2/0x6e0 btrfs_balance+0x72d/0x18d0 btrfs_ioctl_balance+0x3de/0x4c0 btrfs_ioctl+0x30ab/0x44a0 ksys_ioctl+0xa1/0xe0 __x64_sys_ioctl+0x43/0x50 do_syscall_64+0x77/0x2c0 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (&delayed_node->mutex){+.+.}: __lock_acquire+0x197e/0x2550 lock_acquire+0x103/0x220 __mutex_lock+0x13d/0xce0 mutex_lock_nested+0x1b/0x20 __btrfs_release_delayed_node+0x7c/0x5b0 btrfs_remove_delayed_node+0x49/0x50 btrfs_evict_inode+0x6fc/0x900 evict+0x19a/0x2c0 dispose_list+0xa0/0xe0 prune_icache_sb+0xbd/0xf0 super_cache_scan+0x1b5/0x250 do_shrink_slab+0x1f6/0x530 shrink_slab+0x32e/0x410 shrink_node+0x2a5/0xba0 balance_pgdat+0x4bd/0x8a0 kswapd+0x35a/0x800 kthread+0x1e9/0x210 ret_from_fork+0x3a/0x50 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&delayed_node->mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 3 locks held by kswapd0/1133: #0: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30 #1: ffffffff8fc380d8 (shrinker_rwsem){++++}, at: shrink_slab+0x1e8/0x410 #2: ffff8881e0e6c0e8 (&type->s_umount_key#42){++++}, at: trylock_super+0x1b/0x70 stack backtrace: CPU: 2 PID: 1133 Comm: kswapd0 Not tainted 5.6.0-c6f0579d496a+ #53 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack+0xc1/0x11a print_circular_bug.isra.38.cold.57+0x145/0x14a check_noncircular+0x2a9/0x2f0 ? print_circular_bug.isra.38+0x130/0x130 ? stack_trace_consume_entry+0x90/0x90 ? save_trace+0x3cc/0x420 __lock_acquire+0x197e/0x2550 ? btrfs_inode_clear_file_extent_range+0x9b/0xb0 ? register_lock_class+0x960/0x960 lock_acquire+0x103/0x220 ? __btrfs_release_delayed_node+0x7c/0x5b0 __mutex_lock+0x13d/0xce0 ? __btrfs_release_delayed_node+0x7c/0x5b0 ? __asan_loadN+0xf/0x20 ? pvclock_clocksource_read+0xeb/0x190 ? __btrfs_release_delayed_node+0x7c/0x5b0 ? mutex_lock_io_nested+0xc20/0xc20 ? __kasan_check_read+0x11/0x20 ? check_chain_key+0x1e6/0x2e0 mutex_lock_nested+0x1b/0x20 ? mutex_lock_nested+0x1b/0x20 __btrfs_release_delayed_node+0x7c/0x5b0 btrfs_remove_delayed_node+0x49/0x50 btrfs_evict_inode+0x6fc/0x900 ? btrfs_setattr+0x840/0x840 ? do_raw_spin_unlock+0xa8/0x140 evict+0x19a/0x2c0 dispose_list+0xa0/0xe0 prune_icache_sb+0xbd/0xf0 ? invalidate_inodes+0x310/0x310 super_cache_scan+0x1b5/0x250 do_shrink_slab+0x1f6/0x530 shrink_slab+0x32e/0x410 ? do_shrink_slab+0x530/0x530 ? do_shrink_slab+0x530/0x530 ? __kasan_check_read+0x11/0x20 ? mem_cgroup_protected+0x13d/0x260 shrink_node+0x2a5/0xba0 balance_pgdat+0x4bd/0x8a0 ? mem_cgroup_shrink_node+0x490/0x490 ? _raw_spin_unlock_irq+0x27/0x40 ? finish_task_switch+0xce/0x390 ? rcu_read_lock_bh_held+0xb0/0xb0 kswapd+0x35a/0x800 ? _raw_spin_unlock_irqrestore+0x4c/0x60 ? balance_pgdat+0x8a0/0x8a0 ? finish_wait+0x110/0x110 ? __kasan_check_read+0x11/0x20 ? __kthread_parkme+0xc6/0xe0 ? balance_pgdat+0x8a0/0x8a0 kthread+0x1e9/0x210 ? kthread_create_worker_on_cpu+0xc0/0xc0 ret_from_fork+0x3a/0x50 This is because we hold that delayed node's mutex while doing tree operations. Fix this by just wrapping the searches in nofs. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/delayed-inode.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c index 87414fc9e268f..416fb50a5378c 100644 --- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -18,6 +18,7 @@ */ #include +#include #include "delayed-inode.h" #include "disk-io.h" #include "transaction.h" @@ -833,11 +834,14 @@ static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans, { struct btrfs_fs_info *fs_info = root->fs_info; struct extent_buffer *leaf; + unsigned int nofs_flag; char *ptr; int ret; + nofs_flag = memalloc_nofs_save(); ret = btrfs_insert_empty_item(trans, root, path, &delayed_item->key, delayed_item->data_len); + memalloc_nofs_restore(nofs_flag); if (ret < 0 && ret != -EEXIST) return ret; @@ -966,6 +970,7 @@ static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans, struct btrfs_delayed_node *node) { struct btrfs_delayed_item *curr, *prev; + unsigned int nofs_flag; int ret = 0; do_again: @@ -974,7 +979,9 @@ static int btrfs_delete_delayed_items(struct btrfs_trans_handle *trans, if (!curr) goto delete_fail; + nofs_flag = memalloc_nofs_save(); ret = btrfs_search_slot(trans, root, &curr->key, path, -1, 1); + memalloc_nofs_restore(nofs_flag); if (ret < 0) goto delete_fail; else if (ret > 0) { @@ -1041,6 +1048,7 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans, struct btrfs_key key; struct btrfs_inode_item *inode_item; struct extent_buffer *leaf; + unsigned int nofs_flag; int mod; int ret; @@ -1053,7 +1061,9 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans, else mod = 1; + nofs_flag = memalloc_nofs_save(); ret = btrfs_lookup_inode(trans, root, path, &key, mod); + memalloc_nofs_restore(nofs_flag); if (ret > 0) { btrfs_release_path(path); return -ENOENT; @@ -1104,7 +1114,10 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans, key.type = BTRFS_INODE_EXTREF_KEY; key.offset = -1; + + nofs_flag = memalloc_nofs_save(); ret = btrfs_search_slot(trans, root, &key, path, -1, 1); + memalloc_nofs_restore(nofs_flag); if (ret < 0) goto err_out; ASSERT(ret); -- 2.20.1