On 01/16/2014 03:17 PM, Peter Zijlstra wrote:
On Thu, Jan 16, 2014 at 02:48:51PM +0100, Daniel Lezcano wrote:3570 sched_getparam(3570, { 0 }) = 0 3570 sched_getscheduler(3570) = 0 (SCHED_OTHER) 3570 sched_get_priority_min(SCHED_OTHER) = 0 3570 sched_get_priority_max(SCHED_OTHER) = 0 3571 sched_get_priority_min(SCHED_OTHER) = 0 3571 sched_get_priority_max(SCHED_OTHER) = 0 3571 sched_get_priority_min(SCHED_OTHER) = 0 3571 sched_get_priority_max(SCHED_OTHER) = 0 3571 sched_setscheduler(3572, SCHED_OTHER, { 0 } <unfinished ...> 3571 <... sched_setscheduler resumed> ) = 0 3571 sched_get_priority_min(SCHED_OTHER <unfinished ...> 3571 <... sched_get_priority_min resumed> ) = 0 3571 sched_get_priority_max(SCHED_OTHER <unfinished ...> 3571 <... sched_get_priority_max resumed> ) = 0 3571 sched_setscheduler(3573, SCHED_OTHER, { 0 } <unfinished ...> 3571 <... sched_setscheduler resumed> ) = -1 EPERM (Operation not permitted) 3571 sched_get_priority_min(SCHED_OTHER <unfinished ...> 3571 <... sched_get_priority_min resumed> ) = 0 3571 sched_get_priority_max(SCHED_OTHER <unfinished ...> 3571 <... sched_get_priority_max resumed> ) = 0 3571 sched_setscheduler(3574, SCHED_OTHER, { 0 } <unfinished ...> 3571 <... sched_setscheduler resumed> ) = -1 EPERM (Operation not permitted)The same strace but on a kernel which does not hang. The calls to sched_setscheduler do not fail. 3292 sched_getparam(3292, { 0 }) = 0 3292 sched_getscheduler(3292) = 0 (SCHED_OTHER) 3292 sched_get_priority_min(SCHED_OTHER) = 0 3292 sched_get_priority_max(SCHED_OTHER) = 0 3293 sched_get_priority_min(SCHED_OTHER) = 0 3293 sched_get_priority_max(SCHED_OTHER) = 0 3293 sched_get_priority_min(SCHED_OTHER) = 0 3293 sched_get_priority_max(SCHED_OTHER) = 0 3293 sched_setscheduler(3294, SCHED_OTHER, { 0 } <unfinished ...> 3293 <... sched_setscheduler resumed> ) = 0 3293 sched_get_priority_min(SCHED_OTHER <unfinished ...> 3293 <... sched_get_priority_min resumed> ) = 0 3293 sched_get_priority_max(SCHED_OTHER <unfinished ...> 3293 <... sched_get_priority_max resumed> ) = 0 3293 sched_setscheduler(3295, SCHED_OTHER, { 0 } <unfinished ...> 3293 <... sched_setscheduler resumed> ) = 0 3293 sched_get_priority_min(SCHED_OTHER <unfinished ...> 3293 <... sched_get_priority_min resumed> ) = 0 3293 sched_get_priority_max(SCHED_OTHER <unfinished ...> 3293 <... sched_get_priority_max resumed> ) = 0 3293 sched_setscheduler(3296, SCHED_OTHER, { 0 } <unfinished ...> 3293 <... sched_setscheduler resumed> ) = 0 The EPERM error comes from kernel/sched/core.c:3303 ... if (fair_policy(policy)) { if (!can_nice(p, attr->sched_nice)) return -EPERM; } ... But I don't know why this is leading to block a process or making rsyslogd being not woken up by a packet coming in the af_unix socket.Could you test with a fresh tip/master, Ingo just pushed out a stack of fixes, in particularly: e3de300d1212b ("sched: Preserve the nice level over sched_setscheduler() and sched_setparam() calls") 39fd8fd22b322 ("sched: Fix up scheduler syscall LTP fails") Could have affected things. Meanwhile I'll try and better read what the above says.
Already tested. The last commits do not change the issue described above. -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
