diff options
author | Josef Bacik <josef@toxicpanda.com> | 2020-03-19 10:11:32 -0400 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2020-03-25 16:26:00 +0100 |
commit | 351cbf6e4410e7ece05e35d0a07320538f2418b4 (patch) | |
tree | 56cc2fef3f1ef66413f58b5a7cef0cabbc0a1cc7 /fs | |
parent | abdd9feb45ed7e9cc55b60a58deba9ca78d46352 (diff) | |
download | linux-351cbf6e4410e7ece05e35d0a07320538f2418b4.tar.bz2 |
btrfs: use nofs allocations for running delayed items
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 <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/delayed-inode.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c index f678980fe564..bf1595a42a98 100644 --- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -6,6 +6,7 @@ #include <linux/slab.h> #include <linux/iversion.h> +#include <linux/sched/mm.h> #include "misc.h" #include "delayed-inode.h" #include "disk-io.h" @@ -803,11 +804,14 @@ static int btrfs_insert_delayed_item(struct btrfs_trans_handle *trans, struct btrfs_delayed_item *delayed_item) { 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; @@ -935,6 +939,7 @@ 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: @@ -943,7 +948,9 @@ do_again: 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) { @@ -1010,6 +1017,7 @@ 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; @@ -1022,7 +1030,9 @@ 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; @@ -1073,7 +1083,10 @@ search: 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); |