btrfs: fix lockdep splat in btrfs_alloc_subvolume_writers
PATCH 1/1 btrfs: fix lockdep splat in btrfs_alloc_subvolume_writers
From: Jeff Mahoney <[email protected]>
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--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
fs/btrfs/disk-io.c +1 -1
@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)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);
Signature · 1 line
2.15.1
Quoted 399 lines · On Fri, Mar 16, 2018 at 11:36 AM, <[email protected]> wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_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_mutexPossible 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+0x16/0x50the 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
Quoted 9 lines
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
Looks OK to me.
thanks,
liubo
Quoted 25 lines
Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +1
-2@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)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); --2.15.1
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Quoted 16 lines · On 16.03.2018 20:36, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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]
Quoted 4 lines
The
percpu_counter_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.
Given there is effort underway to actually kill GFP_NOFS and replace it with the context annotation routines, shouldn't instead use those routines directly ?
<snip>
Quoted 19 lines · Nikolay Borisov
Quoted 16 lines · On 16.03.2018 20:36, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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]
Quoted 8 lines
Quoted 4 lines
The
percpu_counter_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Given there is effort underway to actually kill
GFP_NOFSand replace it with the context annotation routines, shouldn't instead use those routines directly ?
I don't think those have landed yet. When they do, it should obsolete the gfp flags here in any context since we can also read roots from code that doesn't need GFP_NOFS.
-Jeff
Signature · 2 lines
Jeff Mahoney SUSE Labs
Quoted 31 lines · On Fri, Mar 16, 2018 at 02:36:27PM -0400, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +0
-0
fs/btrfs/disk-io.c static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void) · line 1111
Quoted 5 lines
fs/btrfs/disk-io.c +1
-1@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)if (!writers)return ERR_PTR (-ENOMEM ); - ret =percpu_counter_init (&writers->counter,0 ,GFP_KERNEL ); + ret =percpu_counter_init (&writers->counter,0 ,GFP_NOFS );
A line above the diff context is another allocation that does GFP_NOFS, so one of the gfp flags were wrong.
Looks like there's another instance where percpu allocates withGFP_KERNEL: create_space_info that can be called from the path that allocates chunks, so this also looks like a NOFS candidate.
And in the same function, there's another indirect and hidden GFP_KERNEL allocation from kobject_init_and_add. So in this case we can't fix all the gfp problems at the call site and will have to use the scoped approach eventually.
I haven't found any instance of such lockdep reports in my logs (over a long period), so it's quite unlikely to end up in the recursive allocation.
Patch added to next, thanks.
Quoted 35 lines · David Sterba
Quoted 34 lines · On Fri, Mar 16, 2018 at 02:36:27PM -0400, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +0
-0@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)if (!writers)return ERR_PTR (-ENOMEM );
Quoted 5 lines
fs/btrfs/disk-io.c static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void) · line 1111
Quoted 2 lines
fs/btrfs/disk-io.c +1
-1- ret =percpu_counter_init (&writers->counter,0 ,GFP_KERNEL ); + ret =percpu_counter_init (&writers->counter,0 ,GFP_NOFS );A line above the diff context is another allocation that does
GFP_NOFS, so one of the gfp flags were wrong.
This one was wrong. It was initially implicitly GFP_KERNEL until Tejun added the gfp_t argument and used GFP_KERNEL for most of the sites. Since that was effectively a no-op, it was the right thing for him to do without asking every subsystem maintainer their preference.
Quoted 3 lines
Looks like there's another instance where percpu allocates with
GFP_KERNEL:create_space_infothat can be called from the path that allocates chunks, so this also looks like a NOFS candidate.
That's probably for the same reason.
Quoted 4 lines
And in the same function, there's another indirect and hidden
GFP_KERNELallocation fromkobject_init_and_add. So in this case we can't fix all the gfp problems at the call site and will have to use the scoped approach eventually.
Yep. That's not a huge barrier, though. We can push the kobject_add into a workqueue pretty easily.
Quoted 5 lines
I haven't found any instance of such lockdep reports in my logs (over a long period), so it's quite unlikely to end up in the recursive allocation.
Patch added to next, thanks.
When hunting to see if this had already been fixed, I did find two reports. One from Qu from April of last year and another from Mike Galbraith in 2016.
-Jeff
Signature · 2 lines
Jeff Mahoney SUSE Labs
Quoted 41 lines · David Sterba
Quoted 31 lines · On Fri, Mar 16, 2018 at 02:36:27PM -0400, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +0
-0fs/btrfs/disk-io.c static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void) · line 1111
Quoted 5 lines
fs/btrfs/disk-io.c +1
-1@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)if (!writers)return ERR_PTR (-ENOMEM ); - ret =percpu_counter_init (&writers->counter,0 ,GFP_KERNEL ); + ret =percpu_counter_init (&writers->counter,0 ,GFP_NOFS );A line above the diff context is another allocation that does
GFP_NOFS, so one of the gfp flags were wrong.
Quoted 3 lines
Looks like there's another instance where percpu allocates with
GFP_KERNEL:create_space_infothat can be called from the path that allocates chunks, so this also looks like a NOFS candidate.
We can get rid of this case entirely. Those call sites should be removed since the space_infos are all allocated at mount time.
-Jeff
Signature · 2 lines
Jeff Mahoney SUSE Labs
Quoted 42 lines · Jeff Mahoney
Quoted 41 lines · David Sterba
Quoted 31 lines · On Fri, Mar 16, 2018 at 02:36:27PM -0400, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +0
-0fs/btrfs/disk-io.c static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void) · line 1111
Quoted 5 lines
fs/btrfs/disk-io.c +1
-1@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)if (!writers)return ERR_PTR (-ENOMEM ); - ret =percpu_counter_init (&writers->counter,0 ,GFP_KERNEL ); + ret =percpu_counter_init (&writers->counter,0 ,GFP_NOFS );A line above the diff context is another allocation that does
GFP_NOFS, so one of the gfp flags were wrong.
Quoted 6 lines
Quoted 3 lines
Looks like there's another instance where percpu allocates with
GFP_KERNEL:create_space_infothat can be called from the path that allocates chunks, so this also looks like a NOFS candidate.We can get rid of this case entirely. Those call sites should be removed since the
space_infosare all allocated at mount time.
That would be great and make a few things simpler. So this means that __find_space_info never fails once the space infos are properly initialized, right? That was my concern in do_chunk_alloc and btrfs_make_block_group (that's called from __btrfs_alloc_chunk).
Quoted 47 lines · David Sterba
Quoted 46 lines · Jeff Mahoney
Quoted 44 lines · David Sterba
Quoted 31 lines · On Fri, Mar 16, 2018 at 02:36:27PM -0400, [email protected] wrote:
From: Jeff Mahoney <[email protected]>
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_initcall inbtrfs_alloc_subvolume_writersusesGFP_KERNEL, which we can't do during transaction commit.This switches it to
GFP_NOFS.Signed-off-by Jeff Mahoney <[email protected]>--- fs/btrfs/disk-io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)fs/btrfs/disk-io.c +0
-0fs/btrfs/disk-io.c static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void) · line 1111
Quoted 5 lines
fs/btrfs/disk-io.c +1
-1@@ -1108,7 +1108,7 @@ static struct btrfs_subvolume_writers *btrfs_alloc_subvolume_writers(void)if (!writers)return ERR_PTR (-ENOMEM ); - ret =percpu_counter_init (&writers->counter,0 ,GFP_KERNEL ); + ret =percpu_counter_init (&writers->counter,0 ,GFP_NOFS );A line above the diff context is another allocation that does
GFP_NOFS, so one of the gfp flags were wrong.Looks like there's another instance where percpu allocates with
GFP_KERNEL:create_space_infothat can be called from the path that allocates chunks, so this also looks like a NOFS candidate.
Quoted 7 lines
Quoted 2 lines
We can get rid of this case entirely. Those call sites should be removed since the
space_infosare all allocated at mount time.That would be great and make a few things simpler. So this means that
__find_space_infonever fails once the space infos are properly initialized, right? That was my concern indo_chunk_allocandbtrfs_make_block_group(that's called from__btrfs_alloc_chunk).
That's a different case. The raid levels are added when the first block group of a particular read level is loaded up. That can happen when the block groups are read in initially, where it should be safe to use GFP_KERNEL or when a chunk of a new type is allocated. The thing is that a chunk of a new type will only be allocated when we're converting via balance, so we may be able to do the kobject_add for the raid level when we start the balance rather than wait for it to create the block group.
-Jeff
Signature · 2 lines
Jeff Mahoney SUSE Labs