* Mike Galbraith | 2015-03-24 08:14:49 [+0100]: >do_set_cpus_allowed() is not safe vs ->sched_class change. > >crash> bt >PID: 11676 TASK: ffff88026f979da0 CPU: 22 COMMAND: "sync_unplug/22" > #0 [ffff880274d25bc8] machine_kexec at ffffffff8103b41c > #1 [ffff880274d25c18] crash_kexec at ffffffff810d881a > #2 [ffff880274d25cd8] oops_end at ffffffff81525818 > #3 [ffff880274d25cf8] do_invalid_op at ffffffff81003096 > #4 [ffff880274d25d90] invalid_op at ffffffff8152d3de > [exception RIP: set_cpus_allowed_rt+18] > RIP: ffffffff8109e012 RSP: ffff880274d25e48 RFLAGS: 00010202 > RAX: ffffffff8109e000 RBX: ffff88026f979da0 RCX: ffff8802770cb6e8 > RDX: 0000000000000000 RSI: ffffffff81add700 RDI: ffff88026f979da0 > RBP: ffff880274d25e78 R8: ffffffff816112e0 R9: 0000000000000001 > R10: 0000000000000001 R11: 0000000000011940 R12: ffff88026f979da0 > R13: ffff8802770cb6d0 R14: ffff880274d25fd8 R15: 0000000000000000 > ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > #5 [ffff880274d25e60] do_set_cpus_allowed at ffffffff8108e65f > #6 [ffff880274d25e80] sync_unplug_thread at ffffffff81058c08 > #7 [ffff880274d25ed8] kthread at ffffffff8107cad6 > #8 [ffff880274d25f50] ret_from_fork at ffffffff8152bbbc >crash> task_struct ffff88026f979da0 | grep class > sched_class = 0xffffffff816111e0 <fair_sched_class+64>, Is this a one-time thing or can you reproduce this? What happen here? I doubt p vanished. +18 is mostlikely the "migrate_disabled_updated()" check. I doubt p->sched_class->set_cpus_allowed or p->sched_class vanish between testing for it and invoking it, or did it? >Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx> >Cc: stable-rt@xxxxxxxxxxxxxxx >--- > kernel/cpu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >--- a/kernel/cpu.c >+++ b/kernel/cpu.c >@@ -265,7 +265,7 @@ static int sync_unplug_thread(void *data > * we don't want any more work on this CPU. > */ > current->flags &= ~PF_NO_SETAFFINITY; >- do_set_cpus_allowed(current, cpu_present_mask); >+ set_cpus_allowed_ptr(current, cpu_present_mask); > migrate_me(); > return 0; > } Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
