Messages in this thread | | | Date | Mon, 21 Sep 2009 10:51:55 +0200 | From | Heiko Carstens <> | Subject | [BUG] events process running on wrong cpu |
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Hi,
with todays git from time to time I get this (s390 defconfig):
BUG: using smp_processor_id() in preemptible [00000000] code: events/1/16 caller is vmstat_update+0x28/0x74 CPU: 0 Not tainted 2.6.31-06618-gebc79c4-dirty #3 Process events/1 (pid: 16, task: 000000003fcbea00, ksp: 000000003fcd7cd8) 000000003fcd7da8 000000003fcd7d28 0000000000000002 0000000000000000 000000003fcd7dc8 000000003fcd7d40 000000003fcd7d40 00000000003fe46a 000000000001ffff 000000003fcd7e70 000000000192b128 ffffffffffffc000 000000000000000d 000000000000000c 000000003fcd7d90 0000000000000000 0000000000000000 0000000000016bda 000000003fcd7d28 000000003fcd7d68 Call Trace: ([<0000000000016aea>] show_trace+0xe6/0x134) [<0000000000202a5e>] debug_smp_processor_id+0x112/0x12c [<00000000000b302c>] vmstat_update+0x28/0x74 [<000000000005fb9a>] worker_thread+0x19a/0x27c [<0000000000065f80>] kthread+0xa0/0xa8 [<000000000001b786>] kernel_thread_starter+0x6/0xc [<000000000001b780>] kernel_thread_starter+0x0/0xc
Please note that events/1 is running in cpu 0 (!).
But (with a patched procfs output):
[root@h4245004 ~]# cat /proc/16/status Name: events/1 State: S (sleeping) Tgid: 16 Pid: 16 PPid: 2 TracerPid: 0 Uid: 0 0 0 0 Gid: 0 0 0 0 FDSize: 64 Groups: Threads: 1 SigQ: 0/4096 SigPnd: 0000000000000000 ShdPnd: 0000000000000000 SigBlk: 0000000000000000 SigIgn: ffffffffffffffff SigCgt: 0000000000000000 CapInh: 0000000000000000 CapPrm: ffffffffffffffff CapEff: fffffffffffffeff CapBnd: fffffffffffffeff Cpus_allowed: 00000002 <---------- Cpus_allowed_list: 1 <---------- task: 000000003fcbea00, ksp: 000000003fcd7cd8 User PSW : 0704000180000000 000000000001b780 User GPRS: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000065ee0 000000003fe73cf8 000000000004d414 0000000000000000 0000000000000000 0000000000000000 000000003fcd7eb8 User ACRS: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 voluntary_ctxt_switches: 55 nonvoluntary_ctxt_switches: 1
So the cpus_allowed mask is correct (later on at least). Looks like the created kthread ran before its cpus_allowed mask was set. Looking at the code this shouldn't happen. But still...
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