Frederic Weisbecker 7f6575f1fb cputime: Use local_clock() for full dynticks cputime accounting ... Running the full dynticks cputime accounting with preemptible kernel debugging trigger the following warning: [ 4.488303] BUG: using smp_processor_id() in preemptible [00000000] code: init/1 [ 4.490971] caller is native_sched_clock+0x22/0x80 [ 4.493663] Pid: 1, comm: init Not tainted 3.8.0+ #13 [ 4.496376] Call Trace: [ 4.498996] [<ffffffff813410eb>] debug_smp_processor_id+0xdb/0xf0 [ 4.501716] [<ffffffff8101e642>] native_sched_clock+0x22/0x80 [ 4.504434] [<ffffffff8101db99>] sched_clock+0x9/0x10 [ 4.507185] [<ffffffff81096ccd>] fetch_task_cputime+0xad/0x120 [ 4.509916] [<ffffffff81096dd5>] task_cputime+0x35/0x60 [ 4.512622] [<ffffffff810f146e>] acct_update_integrals+0x1e/0x40 [ 4.515372] [<ffffffff8117d2cf>] do_execve_common+0x4ff/0x5c0 [ 4.518117] [<ffffffff8117cf14>] ? do_execve_common+0x144/0x5c0 [ 4.520844] [<ffffffff81867a10>] ? rest_init+0x160/0x160 [ 4.523554] [<ffffffff8117d457>] do_execve+0x37/0x40 [ 4.526276] [<ffffffff810021a3>] run_init_process+0x23/0x30 [ 4.528953] [<ffffffff81867aac>] kernel_init+0x9c/0xf0 [ 4.531608] [<ffffffff8188356c>] ret_from_fork+0x7c/0xb0 We use sched_clock() to perform and fixup the cputime accounting. However we are calling it with preemption enabled from the read side, which trigger the bug above. To fix this up, use local_clock() instead. It takes care of preemption and also provide a more reliable clock source. This is welcome for this kind of statistic that is widely relied on in userspace. Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Ingo Molnar <mingo@kernel.org> Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1361636925-22288-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>		2013-02-24 12:57:16 +01:00
..
auto_group.c	Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled"	2012-12-11 10:23:45 +01:00
auto_group.h	Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled"	2012-12-11 10:23:45 +01:00
clock.c
core.c	sched/core: Remove the obsolete and unused nr_uninterruptible() function	2013-02-20 11:39:24 +01:00
cpupri.c	sched/rt: Move rt specific bits into new header file	2013-02-07 20:51:08 +01:00
cpupri.h
cputime.c	cputime: Use local_clock() for full dynticks cputime accounting	2013-02-24 12:57:16 +01:00
debug.c	sched: Fix /proc/sched_debug failure on very very large systems	2013-02-22 10:27:25 +01:00
fair.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-02-19 18:19:48 -08:00
features.h	Automatic NUMA Balancing V11	2012-12-16 15:18:08 -08:00
idle_task.c	sched/nohz: Rewrite and fix load-avg computation -- again	2012-07-05 20:58:13 +02:00
Makefile	sched: Move cputime code to its own file	2012-08-20 13:05:17 +02:00
rt.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-02-19 18:19:48 -08:00
sched.h	sched/rt: Move rt specific bits into new header file	2013-02-07 20:51:08 +01:00
stats.c	sched: Fix /proc/sched_stat failure on very very large systems	2013-02-22 10:27:24 +01:00
stats.h
stop_task.c	sched: Fix migration thread runtime bogosity	2012-08-13 18:41:55 +02:00