kernel/hung_task.c: break RCU locks based on jiffies
authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Thu, 3 Jan 2019 23:26:31 +0000 (15:26 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 4 Jan 2019 21:13:45 +0000 (13:13 -0800)
commit304ae42739b108305f8d7b3eb3c1aec7c2b643a9
tree6deeb37924ba3177857df47f67507823b57e65d5
parent168e06f7937d96c7222037d8a05565e8a6eb00fe
kernel/hung_task.c: break RCU locks based on jiffies

check_hung_uninterruptible_tasks() is currently calling rcu_lock_break()
for every 1024 threads.  But check_hung_task() is very slow if printk()
was called, and is very fast otherwise.

If many threads within some 1024 threads called printk(), the RCU grace
period might be extended enough to trigger RCU stall warnings.
Therefore, calling rcu_lock_break() for every some fixed jiffies will be
safer.

Link: http://lkml.kernel.org/r/1544800658-11423-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/hung_task.c