Hi.
I am testing hotspare v2 on kernel v4.4.5 (I will try latest Chris' tree later)
now with lockdep debugging enabled. At starting of replacement, lockdep warning
is displayed,
because kstrdup() is called with GFP_NOFS inside of rcu_read_lock/unlock()
block (GFP_NOFS can sleep).
[ 1463.470875] BTRFS critical (device sdc): Fatal error on device /dev/sdf
[ 1463.499091] BTRFS warning (device sdc): device /dev/sdf failed, chunks
degraded
[ 1463.501394] BTRFS info (device sdc): num_devices 4 rw_devices 3
degraded-option: unset
[ 1463.506221]
[ 1463.508572] ===============================
[ 1463.512989] [ INFO: suspicious RCU usage. ]
[ 1463.514194] 4.4.5-scst31x+ #20 Not tainted
[ 1463.515191] -------------------------------
[ 1463.516162] include/linux/rcupdate.h:560 Illegal context switch in RCU
read-side critical section!
[ 1463.519943]
[ 1463.519943] other info that might help us debug this:
[ 1463.519943]
[ 1463.531515]
[ 1463.531515] rcu_scheduler_active = 1, debug_locks = 0
[ 1463.541056] 3 locks held by btrfs-casualty/4702:
[ 1463.542151] #0: (&fs_info->casualty_mutex){+.+...}, at:
[<ffffffffa018325a>] casualty_kthread+0x6a/0x340 [btrfs]
[ 1463.563978] #1: (uuid_mutex){+.+.+.}, at: [<ffffffffa01bfc65>]
btrfs_get_spare_device+0x25/0x1c0 [btrfs]
[ 1463.587380] #2: (rcu_read_lock){......}, at: [<ffffffffa01bfcac>]
btrfs_get_spare_device+0x6c/0x1c0 [btrfs]
[ 1463.606124]
[ 1463.606124] stack backtrace:
[ 1463.612596] CPU: 0 PID: 4702 Comm: btrfs-casualty Not tainted 4.4.5-scst31x+
#20
[ 1463.630796] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[ 1463.649423] 0000000000000000 ffff88005e65fc60 ffffffff813529e3
ffff88005e658580
[ 1463.685195] 0000000000000001 ffff88005e65fc90 ffffffff810d6407
0000000000000000
[ 1463.719570] ffffffff81a270d7 0000000000000b2d 0000000002400040
ffff88005e65fcb8
[ 1463.735510] Call Trace:
[ 1463.741172] [<ffffffff813529e3>] dump_stack+0x85/0xc2
[ 1463.751346] [<ffffffff810d6407>] lockdep_rcu_suspicious+0xd7/0x110
[ 1463.776423] [<ffffffff810add27>] ___might_sleep+0xa7/0x230
[ 1463.792409] [<ffffffff810adef9>] __might_sleep+0x49/0x80
[ 1463.798818] [<ffffffffa01bfd0a>] ? btrfs_get_spare_device+0xca/0x1c0 [btrfs]
[ 1463.814369] [<ffffffff81200ec7>] __kmalloc_track_caller+0x227/0x5e0
[ 1463.828477] [<ffffffff811c0f81>] kstrdup+0x31/0x60
[ 1463.836761] [<ffffffffa01bfd0a>] btrfs_get_spare_device+0xca/0x1c0 [btrfs]
[ 1463.851841] [<ffffffffa01bfcac>] ? btrfs_get_spare_device+0x6c/0x1c0 [btrfs]
[ 1463.867022] [<ffffffffa02038a3>] btrfs_auto_replace_start+0x23/0xd0 [btrfs]
[ 1463.874201] [<ffffffffa01834ad>] casualty_kthread+0x2bd/0x340 [btrfs]
[ 1463.891812] [<ffffffffa01833d1>] ? casualty_kthread+0x1e1/0x340 [btrfs]
[ 1463.908948] [<ffffffffa01831f0>] ? btrfs_check_devices+0x1f0/0x1f0 [btrfs]
[ 1463.920370] [<ffffffff810a70df>] kthread+0xef/0x110
[ 1463.936421] [<ffffffff810dc081>] ?
__raw_callee_save___pv_queued_spin_unlock+0x11/0x20
[ 1463.949868] [<ffffffff810a6ff0>] ? kthread_create_on_node+0x200/0x200
[ 1463.963096] [<ffffffff81637c2f>] ret_from_fork+0x3f/0x70
[ 1463.973053] [<ffffffff810a6ff0>] ? kthread_create_on_node+0x200/0x200
[ 1463.976256] BUG: sleeping function called from invalid context at
mm/slab.c:2861
[ 1463.979936] in_atomic(): 1, irqs_disabled(): 0, pid: 4702, name:
btrfs-casualty
[ 1463.981868] INFO: lockdep is turned off.
[ 1463.987513] CPU: 0 PID: 4702 Comm: btrfs-casualty Not tainted 4.4.5-scst31x+
#20
[ 1463.999678] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS
VirtualBox 12/01/2006
[ 1464.002555] 0000000000000000 ffff88005e65fc90 ffffffff813529e3
ffff88005e658580
[ 1464.022926] ffffffff81a270d7 ffff88005e65fcb8 ffffffff810addf9
ffffffff81a270d7
[ 1464.055231] 0000000000000b2d 0000000000000000 ffff88005e65fce0
ffffffff810adef9
[ 1464.066771] Call Trace:
[ 1464.069301] [<ffffffff813529e3>] dump_stack+0x85/0xc2
[ 1464.074030] [<ffffffff810addf9>] ___might_sleep+0x179/0x230
[ 1464.076525] [<ffffffff810adef9>] __might_sleep+0x49/0x80
[ 1464.078372] [<ffffffffa01bfd0a>] ? btrfs_get_spare_device+0xca/0x1c0 [btrfs]
[ 1464.080315] [<ffffffff81200ec7>] __kmalloc_track_caller+0x227/0x5e0
[ 1464.083712] [<ffffffff811c0f81>] kstrdup+0x31/0x60
[ 1464.099224] [<ffffffffa01bfd0a>] btrfs_get_spare_device+0xca/0x1c0 [btrfs]
[ 1464.102570] [<ffffffffa01bfcac>] ? btrfs_get_spare_device+0x6c/0x1c0 [btrfs]
[ 1464.106557] [<ffffffffa02038a3>] btrfs_auto_replace_start+0x23/0xd0 [btrfs]
[ 1464.113009] [<ffffffffa01834ad>] casualty_kthread+0x2bd/0x340 [btrfs]
[ 1464.115574] [<ffffffffa01833d1>] ? casualty_kthread+0x1e1/0x340 [btrfs]
[ 1464.131337] [<ffffffffa01831f0>] ? btrfs_check_devices+0x1f0/0x1f0 [btrfs]
[ 1464.139141] [<ffffffff810a70df>] kthread+0xef/0x110
[ 1464.151499] [<ffffffff810dc081>] ?
__raw_callee_save___pv_queued_spin_unlock+0x11/0x20
[ 1464.175156] [<ffffffff810a6ff0>] ? kthread_create_on_node+0x200/0x200
[ 1464.194352] [<ffffffff81637c2f>] ret_from_fork+0x3f/0x70
[ 1464.207239] [<ffffffff810a6ff0>] ? kthread_create_on_node+0x200/0x200
[ 1464.232552] BTRFS info (device sdc): dev_replace from <missing disk> (devid
4) to /dev/sdg started
--
Yauhen Kharuzhy
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