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Subject[PATCH 4.14 355/496] btrfs: fix lockdep splat in btrfs_alloc_subvolume_writers
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Mahoney <jeffm@suse.com>

[ Upstream commit 8a5a916d9a35e13576d79cc16e24611821b13e34 ]

While running btrfs/011, I hit the following lockdep splat.

This is the important bit:
pcpu_alloc+0x1ac/0x5e0
__percpu_counter_init+0x4e/0xb0
btrfs_init_fs_root+0x99/0x1c0 [btrfs]
btrfs_get_fs_root.part.54+0x5b/0x150 [btrfs]
resolve_indirect_refs+0x130/0x830 [btrfs]
find_parent_nodes+0x69e/0xff0 [btrfs]
btrfs_find_all_roots_safe+0xa0/0x110 [btrfs]
btrfs_find_all_roots+0x50/0x70 [btrfs]
btrfs_qgroup_prepare_account_extents+0x53/0x90 [btrfs]
btrfs_commit_transaction+0x3ce/0x9b0 [btrfs]

The percpu_counter_init call in btrfs_alloc_subvolume_writers
uses GFP_KERNEL, which we can't do during transaction commit.

This switches it to GFP_NOFS.

========================================================
WARNING: possible irq lock inversion dependency detected
4.12.14-kvmsmall #8 Tainted: G W
--------------------------------------------------------
kswapd0/50 just changed the state of lock:
(&delayed_node->mutex){+.+.-.}, at: [<ffffffffc06994fa>] __btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
but this lock took another, RECLAIM_FS-unsafe lock in the past:
(pcpu_alloc_mutex){+.+.+.}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
Chain exists of:
&delayed_node->mutex --> &found->groups_sem --> pcpu_alloc_mutex

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(pcpu_alloc_mutex);
local_irq_disable();
lock(&delayed_node->mutex);
lock(&found->groups_sem);
<Interrupt>
lock(&delayed_node->mutex);

*** DEADLOCK ***

2 locks held by kswapd0/50:
#0: (shrinker_rwsem){++++..}, at: [<ffffffff811dc11f>] shrink_slab+0x7f/0x5b0
#1: (&type->s_umount_key#30){+++++.}, at: [<ffffffff8126dec6>] trylock_super+0x16/0x50

the shortest dependencies between 2nd lock and 1st lock:
-> (pcpu_alloc_mutex){+.+.+.} ops: 4904 {
HARDIRQ-ON-W at:
__mutex_lock+0x4e/0x8c0
pcpu_alloc+0x1ac/0x5e0
alloc_kmem_cache_cpus.isra.70+0x25/0xa0
__do_tune_cpucache+0x2c/0x220
do_tune_cpucache+0x26/0xc0
enable_cpucache+0x6d/0xf0
kmem_cache_init_late+0x42/0x75
start_kernel+0x343/0x4cb
x86_64_start_kernel+0x127/0x134
secondary_startup_64+0xa5/0xb0
SOFTIRQ-ON-W at:
__mutex_lock+0x4e/0x8c0
pcpu_alloc+0x1ac/0x5e0
alloc_kmem_cache_cpus.isra.70+0x25/0xa0
__do_tune_cpucache+0x2c/0x220
do_tune_cpucache+0x26/0xc0
enable_cpucache+0x6d/0xf0
kmem_cache_init_late+0x42/0x75
start_kernel+0x343/0x4cb
x86_64_start_kernel+0x127/0x134
secondary_startup_64+0xa5/0xb0
RECLAIM_FS-ON-W at:
__kmalloc+0x47/0x310
pcpu_extend_area_map+0x2b/0xc0
pcpu_alloc+0x3ec/0x5e0
alloc_kmem_cache_cpus.isra.70+0x25/0xa0
__do_tune_cpucache+0x2c/0x220
do_tune_cpucache+0x26/0xc0
enable_cpucache+0x6d/0xf0
__kmem_cache_create+0x1bf/0x390
create_cache+0xba/0x1b0
kmem_cache_create+0x1f8/0x2b0
ksm_init+0x6f/0x19d
do_one_initcall+0x50/0x1b0
kernel_init_freeable+0x201/0x289
kernel_init+0xa/0x100
ret_from_fork+0x3a/0x50
INITIAL USE at:
__mutex_lock+0x4e/0x8c0
pcpu_alloc+0x1ac/0x5e0
alloc_kmem_cache_cpus.isra.70+0x25/0xa0
setup_cpu_cache+0x2f/0x1f0
__kmem_cache_create+0x1bf/0x390
create_boot_cache+0x8b/0xb1
kmem_cache_init+0xa1/0x19e
start_kernel+0x270/0x4cb
x86_64_start_kernel+0x127/0x134
secondary_startup_64+0xa5/0xb0
}
... key at: [<ffffffff821d8e70>] pcpu_alloc_mutex+0x70/0xa0
... acquired at:
pcpu_alloc+0x1ac/0x5e0
__percpu_counter_init+0x4e/0xb0
btrfs_init_fs_root+0x99/0x1c0 [btrfs]
btrfs_get_fs_root.part.54+0x5b/0x150 [btrfs]
resolve_indirect_refs+0x130/0x830 [btrfs]
find_parent_nodes+0x69e/0xff0 [btrfs]
btrfs_find_all_roots_safe+0xa0/0x110 [btrfs]
btrfs_find_all_roots+0x50/0x70 [btrfs]
btrfs_qgroup_prepare_account_extents+0x53/0x90 [btrfs]
btrfs_commit_transaction+0x3ce/0x9b0 [btrfs]
transaction_kthread+0x176/0x1b0 [btrfs]
kthread+0x102/0x140
ret_from_fork+0x3a/0x50

-> (&fs_info->commit_root_sem){++++..} ops: 1566382 {
HARDIRQ-ON-W at:
down_write+0x3e/0xa0
cache_block_group+0x287/0x420 [btrfs]
find_free_extent+0x106c/0x12d0 [btrfs]
btrfs_reserve_extent+0xd8/0x170 [btrfs]
cow_file_range.isra.66+0x133/0x470 [btrfs]
run_delalloc_range+0x121/0x410 [btrfs]
writepage_delalloc.isra.50+0xfe/0x180 [btrfs]
__extent_writepage+0x19a/0x360 [btrfs]
extent_write_cache_pages.constprop.56+0x249/0x3e0 [btrfs]
extent_writepages+0x4d/0x60 [btrfs]
do_writepages+0x1a/0x70
__filemap_fdatawrite_range+0xa7/0xe0
btrfs_rename+0x5ee/0xdb0 [btrfs]
vfs_rename+0x52a/0x7e0
SyS_rename+0x351/0x3b0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
HARDIRQ-ON-R at:
down_read+0x35/0x90
caching_thread+0x57/0x560 [btrfs]
normal_work_helper+0x1c0/0x5e0 [btrfs]
process_one_work+0x1e0/0x5c0
worker_thread+0x44/0x390
kthread+0x102/0x140
ret_from_fork+0x3a/0x50
SOFTIRQ-ON-W at:
down_write+0x3e/0xa0
cache_block_group+0x287/0x420 [btrfs]
find_free_extent+0x106c/0x12d0 [btrfs]
btrfs_reserve_extent+0xd8/0x170 [btrfs]
cow_file_range.isra.66+0x133/0x470 [btrfs]
run_delalloc_range+0x121/0x410 [btrfs]
writepage_delalloc.isra.50+0xfe/0x180 [btrfs]
__extent_writepage+0x19a/0x360 [btrfs]
extent_write_cache_pages.constprop.56+0x249/0x3e0 [btrfs]
extent_writepages+0x4d/0x60 [btrfs]
do_writepages+0x1a/0x70
__filemap_fdatawrite_range+0xa7/0xe0
btrfs_rename+0x5ee/0xdb0 [btrfs]
vfs_rename+0x52a/0x7e0
SyS_rename+0x351/0x3b0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
SOFTIRQ-ON-R at:
down_read+0x35/0x90
caching_thread+0x57/0x560 [btrfs]
normal_work_helper+0x1c0/0x5e0 [btrfs]
process_one_work+0x1e0/0x5c0
worker_thread+0x44/0x390
kthread+0x102/0x140
ret_from_fork+0x3a/0x50
INITIAL USE at:
down_write+0x3e/0xa0
cache_block_group+0x287/0x420 [btrfs]
find_free_extent+0x106c/0x12d0 [btrfs]
btrfs_reserve_extent+0xd8/0x170 [btrfs]
cow_file_range.isra.66+0x133/0x470 [btrfs]
run_delalloc_range+0x121/0x410 [btrfs]
writepage_delalloc.isra.50+0xfe/0x180 [btrfs]
__extent_writepage+0x19a/0x360 [btrfs]
extent_write_cache_pages.constprop.56+0x249/0x3e0 [btrfs]
extent_writepages+0x4d/0x60 [btrfs]
do_writepages+0x1a/0x70
__filemap_fdatawrite_range+0xa7/0xe0
btrfs_rename+0x5ee/0xdb0 [btrfs]
vfs_rename+0x52a/0x7e0
SyS_rename+0x351/0x3b0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
}
... key at: [<ffffffffc0729578>] __key.61970+0x0/0xfffffffffff9aa88 [btrfs]
... acquired at:
cache_block_group+0x287/0x420 [btrfs]
find_free_extent+0x106c/0x12d0 [btrfs]
btrfs_reserve_extent+0xd8/0x170 [btrfs]
btrfs_alloc_tree_block+0x12f/0x4c0 [btrfs]
btrfs_create_tree+0xbb/0x2a0 [btrfs]
btrfs_create_uuid_tree+0x37/0x140 [btrfs]
open_ctree+0x23c0/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> (&found->groups_sem){++++..} ops: 2134587 {
HARDIRQ-ON-W at:
down_write+0x3e/0xa0
__link_block_group+0x34/0x130 [btrfs]
btrfs_read_block_groups+0x33d/0x7b0 [btrfs]
open_ctree+0x2054/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
HARDIRQ-ON-R at:
down_read+0x35/0x90
btrfs_calc_num_tolerated_disk_barrier_failures+0x113/0x1f0 [btrfs]
open_ctree+0x207b/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
SOFTIRQ-ON-W at:
down_write+0x3e/0xa0
__link_block_group+0x34/0x130 [btrfs]
btrfs_read_block_groups+0x33d/0x7b0 [btrfs]
open_ctree+0x2054/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
SOFTIRQ-ON-R at:
down_read+0x35/0x90
btrfs_calc_num_tolerated_disk_barrier_failures+0x113/0x1f0 [btrfs]
open_ctree+0x207b/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
INITIAL USE at:
down_write+0x3e/0xa0
__link_block_group+0x34/0x130 [btrfs]
btrfs_read_block_groups+0x33d/0x7b0 [btrfs]
open_ctree+0x2054/0x2660 [btrfs]
btrfs_mount+0xd36/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
btrfs_mount+0x18c/0xf90 [btrfs]
mount_fs+0x3a/0x160
vfs_kern_mount+0x66/0x150
do_mount+0x1c1/0xcc0
SyS_mount+0x7e/0xd0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
}
... key at: [<ffffffffc0729488>] __key.59101+0x0/0xfffffffffff9ab78 [btrfs]
... acquired at:
find_free_extent+0xcb4/0x12d0 [btrfs]
btrfs_reserve_extent+0xd8/0x170 [btrfs]
btrfs_alloc_tree_block+0x12f/0x4c0 [btrfs]
__btrfs_cow_block+0x110/0x5b0 [btrfs]
btrfs_cow_block+0xd7/0x290 [btrfs]
btrfs_search_slot+0x1f6/0x960 [btrfs]
btrfs_lookup_inode+0x2a/0x90 [btrfs]
__btrfs_update_delayed_inode+0x65/0x210 [btrfs]
btrfs_commit_inode_delayed_inode+0x121/0x130 [btrfs]
btrfs_evict_inode+0x3fe/0x6a0 [btrfs]
evict+0xc4/0x190
__dentry_kill+0xbf/0x170
dput+0x2ae/0x2f0
SyS_rename+0x2a6/0x3b0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> (&delayed_node->mutex){+.+.-.} ops: 5580204 {
HARDIRQ-ON-W at:
__mutex_lock+0x4e/0x8c0
btrfs_delayed_update_inode+0x46/0x6e0 [btrfs]
btrfs_update_inode+0x83/0x110 [btrfs]
btrfs_dirty_inode+0x62/0xe0 [btrfs]
touch_atime+0x8c/0xb0
do_generic_file_read+0x818/0xb10
__vfs_read+0xdc/0x150
vfs_read+0x8a/0x130
SyS_read+0x45/0xa0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
SOFTIRQ-ON-W at:
__mutex_lock+0x4e/0x8c0
btrfs_delayed_update_inode+0x46/0x6e0 [btrfs]
btrfs_update_inode+0x83/0x110 [btrfs]
btrfs_dirty_inode+0x62/0xe0 [btrfs]
touch_atime+0x8c/0xb0
do_generic_file_read+0x818/0xb10
__vfs_read+0xdc/0x150
vfs_read+0x8a/0x130
SyS_read+0x45/0xa0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
IN-RECLAIM_FS-W at:
__mutex_lock+0x4e/0x8c0
__btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
btrfs_evict_inode+0x22c/0x6a0 [btrfs]
evict+0xc4/0x190
dispose_list+0x35/0x50
prune_icache_sb+0x42/0x50
super_cache_scan+0x139/0x190
shrink_slab+0x262/0x5b0
shrink_node+0x2eb/0x2f0
kswapd+0x2eb/0x890
kthread+0x102/0x140
ret_from_fork+0x3a/0x50
INITIAL USE at:
__mutex_lock+0x4e/0x8c0
btrfs_delayed_update_inode+0x46/0x6e0 [btrfs]
btrfs_update_inode+0x83/0x110 [btrfs]
btrfs_dirty_inode+0x62/0xe0 [btrfs]
touch_atime+0x8c/0xb0
do_generic_file_read+0x818/0xb10
__vfs_read+0xdc/0x150
vfs_read+0x8a/0x130
SyS_read+0x45/0xa0
do_syscall_64+0x79/0x1e0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
}
... key at: [<ffffffffc072d488>] __key.56935+0x0/0xfffffffffff96b78 [btrfs]
... acquired at:
__lock_acquire+0x264/0x11c0
lock_acquire+0xbd/0x1e0
__mutex_lock+0x4e/0x8c0
__btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
btrfs_evict_inode+0x22c/0x6a0 [btrfs]
evict+0xc4/0x190
dispose_list+0x35/0x50
prune_icache_sb+0x42/0x50
super_cache_scan+0x139/0x190
shrink_slab+0x262/0x5b0
shrink_node+0x2eb/0x2f0
kswapd+0x2eb/0x890
kthread+0x102/0x140
ret_from_fork+0x3a/0x50

stack backtrace:
CPU: 1 PID: 50 Comm: kswapd0 Tainted: G W 4.12.14-kvmsmall #8 SLE15 (unreleased)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
Call Trace:
dump_stack+0x78/0xb7
print_irq_inversion_bug.part.38+0x19f/0x1aa
check_usage_forwards+0x102/0x120
? ret_from_fork+0x3a/0x50
? check_usage_backwards+0x110/0x110
mark_lock+0x16c/0x270
__lock_acquire+0x264/0x11c0
? pagevec_lookup_entries+0x1a/0x30
? truncate_inode_pages_range+0x2b3/0x7f0
lock_acquire+0xbd/0x1e0
? __btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
__mutex_lock+0x4e/0x8c0
? __btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
? __btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
? btrfs_evict_inode+0x1f6/0x6a0 [btrfs]
__btrfs_release_delayed_node+0x3a/0x1f0 [btrfs]
btrfs_evict_inode+0x22c/0x6a0 [btrfs]
evict+0xc4/0x190
dispose_list+0x35/0x50
prune_icache_sb+0x42/0x50
super_cache_scan+0x139/0x190
shrink_slab+0x262/0x5b0
shrink_node+0x2eb/0x2f0
kswapd+0x2eb/0x890
kthread+0x102/0x140
? mem_cgroup_shrink_node+0x2c0/0x2c0
? kthread_create_on_node+0x40/0x40
ret_from_fork+0x3a/0x50

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/disk-io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1276,7 +1276,7 @@ static struct btrfs_subvolume_writers *b
if (!writers)
return ERR_PTR(-ENOMEM);

- ret = percpu_counter_init(&writers->counter, 0, GFP_KERNEL);
+ ret = percpu_counter_init(&writers->counter, 0, GFP_NOFS);
if (ret < 0) {
kfree(writers);
return ERR_PTR(ret);

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