From: <gregkh@linuxfoundation.org>
To: josef@toxicpanda.com, dsterba@suse.com
Cc: <stable@vger.kernel.org>
Subject: FAILED: patch "[PATCH] btrfs: sysfs: init devices outside of the chunk_mutex" failed to apply to 5.4-stable tree
Date: Tue, 03 Nov 2020 14:52:43 +0100 [thread overview]
Message-ID: <160441156390189@kroah.com> (raw)
The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ca10845a56856fff4de3804c85e6424d0f6d0cde Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@toxicpanda.com>
Date: Tue, 1 Sep 2020 08:09:01 -0400
Subject: [PATCH] btrfs: sysfs: init devices outside of the chunk_mutex
While running btrfs/061, btrfs/073, btrfs/078, or btrfs/178 we hit the
following lockdep splat:
======================================================
WARNING: possible circular locking dependency detected
5.9.0-rc3+ #4 Not tainted
------------------------------------------------------
kswapd0/100 is trying to acquire lock:
ffff96ecc22ef4a0 (&delayed_node->mutex){+.+.}-{3:3}, at: __btrfs_release_delayed_node.part.0+0x3f/0x330
but task is already holding lock:
ffffffff8dd74700 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (fs_reclaim){+.+.}-{0:0}:
fs_reclaim_acquire+0x65/0x80
slab_pre_alloc_hook.constprop.0+0x20/0x200
kmem_cache_alloc+0x37/0x270
alloc_inode+0x82/0xb0
iget_locked+0x10d/0x2c0
kernfs_get_inode+0x1b/0x130
kernfs_get_tree+0x136/0x240
sysfs_get_tree+0x16/0x40
vfs_get_tree+0x28/0xc0
path_mount+0x434/0xc00
__x64_sys_mount+0xe3/0x120
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #2 (kernfs_mutex){+.+.}-{3:3}:
__mutex_lock+0x7e/0x7e0
kernfs_add_one+0x23/0x150
kernfs_create_link+0x63/0xa0
sysfs_do_create_link_sd+0x5e/0xd0
btrfs_sysfs_add_devices_dir+0x81/0x130
btrfs_init_new_device+0x67f/0x1250
btrfs_ioctl+0x1ef/0x2e20
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #1 (&fs_info->chunk_mutex){+.+.}-{3:3}:
__mutex_lock+0x7e/0x7e0
btrfs_chunk_alloc+0x125/0x3a0
find_free_extent+0xdf6/0x1210
btrfs_reserve_extent+0xb3/0x1b0
btrfs_alloc_tree_block+0xb0/0x310
alloc_tree_block_no_bg_flush+0x4a/0x60
__btrfs_cow_block+0x11a/0x530
btrfs_cow_block+0x104/0x220
btrfs_search_slot+0x52e/0x9d0
btrfs_insert_empty_items+0x64/0xb0
btrfs_insert_delayed_items+0x90/0x4f0
btrfs_commit_inode_delayed_items+0x93/0x140
btrfs_log_inode+0x5de/0x2020
btrfs_log_inode_parent+0x429/0xc90
btrfs_log_new_name+0x95/0x9b
btrfs_rename2+0xbb9/0x1800
vfs_rename+0x64f/0x9f0
do_renameat2+0x320/0x4e0
__x64_sys_rename+0x1f/0x30
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #0 (&delayed_node->mutex){+.+.}-{3:3}:
__lock_acquire+0x119c/0x1fc0
lock_acquire+0xa7/0x3d0
__mutex_lock+0x7e/0x7e0
__btrfs_release_delayed_node.part.0+0x3f/0x330
btrfs_evict_inode+0x24c/0x500
evict+0xcf/0x1f0
dispose_list+0x48/0x70
prune_icache_sb+0x44/0x50
super_cache_scan+0x161/0x1e0
do_shrink_slab+0x178/0x3c0
shrink_slab+0x17c/0x290
shrink_node+0x2b2/0x6d0
balance_pgdat+0x30a/0x670
kswapd+0x213/0x4c0
kthread+0x138/0x160
ret_from_fork+0x1f/0x30
other info that might help us debug this:
Chain exists of:
&delayed_node->mutex --> kernfs_mutex --> fs_reclaim
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(kernfs_mutex);
lock(fs_reclaim);
lock(&delayed_node->mutex);
*** DEADLOCK ***
3 locks held by kswapd0/100:
#0: ffffffff8dd74700 (fs_reclaim){+.+.}-{0:0}, at: __fs_reclaim_acquire+0x5/0x30
#1: ffffffff8dd65c50 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x115/0x290
#2: ffff96ed2ade30e0 (&type->s_umount_key#36){++++}-{3:3}, at: super_cache_scan+0x38/0x1e0
stack backtrace:
CPU: 0 PID: 100 Comm: kswapd0 Not tainted 5.9.0-rc3+ #4
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack+0x8b/0xb8
check_noncircular+0x12d/0x150
__lock_acquire+0x119c/0x1fc0
lock_acquire+0xa7/0x3d0
? __btrfs_release_delayed_node.part.0+0x3f/0x330
__mutex_lock+0x7e/0x7e0
? __btrfs_release_delayed_node.part.0+0x3f/0x330
? __btrfs_release_delayed_node.part.0+0x3f/0x330
? lock_acquire+0xa7/0x3d0
? find_held_lock+0x2b/0x80
__btrfs_release_delayed_node.part.0+0x3f/0x330
btrfs_evict_inode+0x24c/0x500
evict+0xcf/0x1f0
dispose_list+0x48/0x70
prune_icache_sb+0x44/0x50
super_cache_scan+0x161/0x1e0
do_shrink_slab+0x178/0x3c0
shrink_slab+0x17c/0x290
shrink_node+0x2b2/0x6d0
balance_pgdat+0x30a/0x670
kswapd+0x213/0x4c0
? _raw_spin_unlock_irqrestore+0x41/0x50
? add_wait_queue_exclusive+0x70/0x70
? balance_pgdat+0x670/0x670
kthread+0x138/0x160
? kthread_create_worker_on_cpu+0x40/0x40
ret_from_fork+0x1f/0x30
This happens because we are holding the chunk_mutex at the time of
adding in a new device. However we only need to hold the
device_list_mutex, as we're going to iterate over the fs_devices
devices. Move the sysfs init stuff outside of the chunk_mutex to get
rid of this lockdep splat.
CC: stable@vger.kernel.org # 4.4.x: f3cd2c58110dad14e: btrfs: sysfs, rename device_link add/remove functions
CC: stable@vger.kernel.org # 4.4.x
Reported-by: David Sterba <dsterba@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9d169cba8514..c86ffad04641 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2597,9 +2597,6 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
btrfs_set_super_num_devices(fs_info->super_copy,
orig_super_num_devices + 1);
- /* add sysfs device entry */
- btrfs_sysfs_add_devices_dir(fs_devices, device);
-
/*
* we've got more storage, clear any full flags on the space
* infos
@@ -2607,6 +2604,10 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
btrfs_clear_space_info_full(fs_info);
mutex_unlock(&fs_info->chunk_mutex);
+
+ /* Add sysfs device entry */
+ btrfs_sysfs_add_devices_dir(fs_devices, device);
+
mutex_unlock(&fs_devices->device_list_mutex);
if (seeding_dev) {
reply other threads:[~2020-11-03 13:52 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=160441156390189@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=dsterba@suse.com \
--cc=josef@toxicpanda.com \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.