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linux-stable/kernel/sched
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Stanislaw Gruszka 5a8e01f8fa sched/cputime: Do not scale when utime == 0 
scale_stime() silently assumes that stime < rtime, otherwise
when stime == rtime and both values are big enough (operations
on them do not fit in 32 bits), the resulting scaling stime can
be bigger than rtime. In consequence utime = rtime - stime
results in negative value.

User space visible symptoms of the bug are overflowed TIME
values on ps/top, for example:

 $ ps aux | grep rcu
 root         8  0.0  0.0      0     0 ?        S    12:42   0:00 [rcuc/0]
 root         9  0.0  0.0      0     0 ?        S    12:42   0:00 [rcub/0]
 root        10 62422329  0.0  0     0 ?        R    12:42 21114581:37 [rcu_preempt]
 root        11  0.1  0.0      0     0 ?        S    12:42   0:02 [rcuop/0]
 root        12 62422329  0.0  0     0 ?        S    12:42 21114581:35 [rcuop/1]
 root        10 62422329  0.0  0     0 ?        R    12:42 21114581:37 [rcu_preempt]

or overflowed utime values read directly from /proc/$PID/stat

Reference:

  https://lkml.org/lkml/2013/8/20/259

Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: stable@vger.kernel.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20130904131602.GC2564@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-04 16:31:25 +02:00
..
auto_group.c sched/autogroup: Fix race with task_groups list 2013-05-28 09:40:22 +02:00
auto_group.h Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled" 2012-12-11 10:23:45 +01:00
clock.c sched_clock: Prevent 64bit inatomicity on 32bit systems 2013-04-08 11:50:44 +02:00
core.c sched: Consolidate open coded preemptible() checks 2013-08-13 00:40:43 +02:00
cpuacct.c sched/cpuacct/UML: Fix header file dependency bug on the UML build 2013-04-10 15:12:41 +02:00
cpuacct.h sched/cpuacct: Initialize root cpuacct earlier 2013-04-10 13:54:20 +02:00
cpupri.c sched/rt: Move rt specific bits into new header file 2013-02-07 20:51:08 +01:00
cpupri.h
cputime.c sched/cputime: Do not scale when utime == 0 2013-09-04 16:31:25 +02:00
debug.c sched/debug: Remove CONFIG_FAIR_GROUP_SCHED mask 2013-06-28 13:17:17 +02:00
fair.c mm: sched: numa: fix NUMA balancing when !SCHED_DEBUG 2013-07-31 14:41:02 -07:00
features.h mutex: Move mutex spinning code from sched/core.c back to mutex.c 2013-04-19 09:33:34 +02:00
idle_task.c sched: Keep at least 1 tick per second for active dynticks tasks 2013-05-04 08:32:02 +02:00
Makefile sched: Factor out load calculation code from sched/core.c --> sched/proc.c 2013-05-07 13:14:50 +02:00
proc.c sched: Change get_rq_runnable_load() to static and inline 2013-06-27 10:07:44 +02:00
rt.c sched/rt: Simplify pull_rt_task() logic and remove .leaf_rt_rq_list 2013-06-19 12:58:40 +02:00
sched.h sched/tg: Remove tg.load_weight 2013-06-27 10:07:43 +02:00
stats.c fix a leak in /proc/schedstats 2013-04-29 15:41:45 -04:00
stats.h Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-07-06 14:09:38 -07:00
stop_task.c sched: Use an accessor to read the rq clock 2013-05-28 09:40:27 +02:00