From: Peter Zijlstra Date: Wed, 25 Nov 2015 15:02:07 +0000 (+0100) Subject: sched/core: Fix unserialized r-m-w scribbling stuff X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=be958bdc96f18bc1356177bbb79d46ea0c037b96;p=linux-beck.git sched/core: Fix unserialized r-m-w scribbling stuff Some of the sched bitfieds (notably sched_reset_on_fork) can be set on other than current, this can cause the r-m-w to race with other updates. Since all the sched bits are serialized by scheduler locks, pull them in a separate word. Reported-by: Tejun Heo Signed-off-by: Peter Zijlstra (Intel) Cc: Dmitry Vyukov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sasha Levin Cc: Thomas Gleixner Cc: akpm@linux-foundation.org Cc: hannes@cmpxchg.org Cc: mhocko@kernel.org Cc: vdavydov@parallels.com Link: http://lkml.kernel.org/r/20151125150207.GM11639@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- diff --git a/include/linux/sched.h b/include/linux/sched.h index 9cf9dd1c4cbe..fa39434e3fdd 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1455,14 +1455,15 @@ struct task_struct { /* Used for emulating ABI behavior of previous Linux versions */ unsigned int personality; - unsigned in_execve:1; /* Tell the LSMs that the process is doing an - * execve */ - unsigned in_iowait:1; - - /* Revert to default priority/policy when forking */ + /* scheduler bits, serialized by scheduler locks */ unsigned sched_reset_on_fork:1; unsigned sched_contributes_to_load:1; unsigned sched_migrated:1; + unsigned :0; /* force alignment to the next boundary */ + + /* unserialized, strictly 'current' */ + unsigned in_execve:1; /* bit to tell LSMs we're in execve */ + unsigned in_iowait:1; #ifdef CONFIG_MEMCG unsigned memcg_may_oom:1; #endif