Paul E. McKenney 4e79752c25 sched: Mark RCU reader in sched_show_task() ... When sched_show_task() is invoked from try_to_freeze_tasks(), there is no RCU read-side critical section, resulting in the following splat: [ 125.780730] =============================== [ 125.780766] [ INFO: suspicious RCU usage. ] [ 125.780804] 3.7.0-rc3+ #988 Not tainted [ 125.780838] ------------------------------- [ 125.780875] /home/rafael/src/linux/kernel/sched/core.c:4497 suspicious rcu_dereference_check() usage! [ 125.780946] [ 125.780946] other info that might help us debug this: [ 125.780946] [ 125.781031] [ 125.781031] rcu_scheduler_active = 1, debug_locks = 0 [ 125.781087] 4 locks held by s2ram/4211: [ 125.781120] #0: (&buffer->mutex){+.+.+.}, at: [<ffffffff811e2acf>] sysfs_write_file+0x3f/0x160 [ 125.781233] #1: (s_active#94){.+.+.+}, at: [<ffffffff811e2b58>] sysfs_write_file+0xc8/0x160 [ 125.781339] #2: (pm_mutex){+.+.+.}, at: [<ffffffff81090a81>] pm_suspend+0x81/0x230 [ 125.781439] #3: (tasklist_lock){.?.?..}, at: [<ffffffff8108feed>] try_to_freeze_tasks+0x2cd/0x3f0 [ 125.781543] [ 125.781543] stack backtrace: [ 125.781584] Pid: 4211, comm: s2ram Not tainted 3.7.0-rc3+ #988 [ 125.781632] Call Trace: [ 125.781662] [<ffffffff810a3c73>] lockdep_rcu_suspicious+0x103/0x140 [ 125.781719] [<ffffffff8107cf21>] sched_show_task+0x121/0x180 [ 125.781770] [<ffffffff8108ffb4>] try_to_freeze_tasks+0x394/0x3f0 [ 125.781823] [<ffffffff810903b5>] freeze_kernel_threads+0x25/0x80 [ 125.781876] [<ffffffff81090b65>] pm_suspend+0x165/0x230 [ 125.781924] [<ffffffff8108fa29>] state_store+0x99/0x100 [ 125.781975] [<ffffffff812f5867>] kobj_attr_store+0x17/0x20 [ 125.782038] [<ffffffff811e2b71>] sysfs_write_file+0xe1/0x160 [ 125.782091] [<ffffffff811667a6>] vfs_write+0xc6/0x180 [ 125.782138] [<ffffffff81166ada>] sys_write+0x5a/0xa0 [ 125.782185] [<ffffffff812ff6ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f [ 125.782242] [<ffffffff81669dd2>] system_call_fastpath+0x16/0x1b This commit therefore adds the needed RCU read-side critical section. Reported-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>		2012-11-16 10:05:58 -08:00
..
auto_group.c	sched: Clean up parameter passing of proc_sched_autogroup_set_nice()	2012-03-02 12:23:49 +01:00
auto_group.h
clock.c
core.c	sched: Mark RCU reader in sched_show_task()	2012-11-16 10:05:58 -08:00
cpupri.c	sched: Fix minor code style issues	2012-07-26 11:47:00 +02:00
cpupri.h
cputime.c	vtime: Consolidate system/idle context detection	2012-09-25 15:42:37 +02:00
debug.c	sched/debug: Fix printing large integers on 32-bit platforms	2012-05-14 15:05:28 +02:00
fair.c	Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2012-10-01 10:43:39 -07:00
features.h	sched: cpu_power: enable ARCH_POWER	2012-09-13 16:52:06 +02:00
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	sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW	2012-09-13 16:52:04 +02:00
sched.h	sched: Remove __ARCH_WANT_INTERRUPTS_ON_CTXSW	2012-09-13 16:52:04 +02:00
stats.c	sched: Remove sched_switch	2012-01-27 13:28:53 +01:00
stats.h
stop_task.c	sched: Fix migration thread runtime bogosity	2012-08-13 18:41:55 +02:00