On 1/19/21 6:13 AM, Daniel Bristot de Oliveira wrote:
Hi Waiman,
Are you aware of this issue:
----- %< -----
[ 88.307857] BUG: sleeping function called from invalid context at
kernel/stop_machine.c:135
[ 88.308796] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 801,
name: sh
[ 88.309785] 6 locks held by sh/801:
[ 88.310265] #0: ffff9f008c575460 (sb_writers#7){.+.+}-{0:0}, at:
ksys_write+0x58/0xd0
[ 88.310906] #1: ffff9f008e9dd088 (&of->mutex){+.+.}-{4:4}, at:
kernfs_fop_write+0xa5/0x1c0
[ 88.311672] #2: ffff9f0092164a88 (kn->active#195){.+.+}-{0:0}, at:
kernfs_fop_write+0xad/0x1c0
[ 88.312456] #3: ffffffffbac68310 (cpu_hotplug_lock){++++}-{0:0}, at:
sched_partition_write+0x72/0x2f0
[ 88.313280] #4: ffffffffbae37090 (&cpuset_rwsem){++++}-{0:0}, at:
sched_partition_write+0x7e/0x2f0
[ 88.314095] #5: ffffffffbad89140 (rcu_read_lock){....}-{1:3}, at:
update_sibling_cpumasks+0x5/0x140
[ 88.314806] Preemption disabled at:
[ 88.314810] [<ffffffffb900454d>] preempt_schedule_thunk+0x16/0x18
[ 88.315815] CPU: 1 PID: 801 Comm: sh Not tainted 5.10.0-rc5+ #10
[ 88.316203] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
1.13.0-2.fc32 04/01/2014
[ 88.316714] Call Trace:
[ 88.316875] dump_stack+0x8b/0xb0
[ 88.317087] ___might_sleep.cold+0x102/0x116
[ 88.317354] stop_one_cpu+0x82/0xa0
[ 88.317578] ? set_cpus_allowed_ptr+0x10/0x10
[ 88.317858] __set_cpus_allowed_ptr+0x1e6/0x1f0
[ 88.318144] update_tasks_cpumask+0x25/0x50
[ 88.318415] update_cpumasks_hier+0x257/0x840
[ 88.318687] update_sibling_cpumasks+0x96/0x140
[ 88.318968] update_prstate+0x1a0/0x1f0
[ 88.319210] sched_partition_write+0x9f/0x2f0
[ 88.319482] kernfs_fop_write+0xdc/0x1c0
[ 88.319730] vfs_write+0xea/0x3b0
[ 88.319943] ksys_write+0x58/0xd0
[ 88.320156] do_syscall_64+0x33/0x40
[ 88.320382] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 88.320692] RIP: 0033:0x7fbbd79be537
[ 88.320915] Code: 0d 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00
f3 0f 1e fa 64 8b 04
25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00
f0 ff ff 77 51 c3
48 83 ec 28 48 89 54 24 18 48 89 74 24
[ 88.322028] RSP: 002b:00007ffd44cc8398 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
[ 88.322479] RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fbbd79be537
[ 88.322910] RDX: 0000000000000005 RSI: 0000558ae69200a0 RDI: 0000000000000001
[ 88.323342] RBP: 0000558ae69200a0 R08: 000000000000000a R09: 0000000000000004
[ 88.323775] R10: 0000558ae6921ba0 R11: 0000000000000246 R12: 0000000000000005
[ 88.325046] R13: 00007fbbd7a90500 R14: 0000000000000005 R15: 00007fbbd7a90700
----- >% -----
I am not aware of that.
void ___might_sleep(const char *file, int line, int preempt_offset)
:
if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
!is_idle_task(current) && !current->non_block_count) ||
system_state == SYSTEM_BOOTING || system_state >
SYSTEM_RUNNING ||
oops_in_progress)
return;
I think the failing test was preempt_count_equals(preempt_offset).
static inline int preempt_count_equals(int preempt_offset)
{
int nested = preempt_count() + rcu_preempt_depth();
return (nested == preempt_offset);
}
preempt_count() is 0 (in_atomic() == 0) and preempt_offset is 0, but
rcu_preempt_depth() should be at least 1 as a rcu_read_lock was held. I
don't think we should prevent sleeping if a rcu_read_lock is held. We
need to look at the reason why rcu_preempt_depth() is included in this test.
Cheers,
Longman
