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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2019-01-03 15:26:31 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-04 13:13:45 -0800
commit304ae42739b108305f8d7b3eb3c1aec7c2b643a9 (patch)
tree6deeb37924ba3177857df47f67507823b57e65d5 /kernel
parent168e06f7937d96c7222037d8a05565e8a6eb00fe (diff)
downloadlinux-304ae42739b108305f8d7b3eb3c1aec7c2b643a9.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/hung_task.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 85af0cde7f46..4a9191617076 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -34,7 +34,7 @@ int __read_mostly sysctl_hung_task_check_count = PID_MAX_LIMIT;
* is disabled during the critical section. It also controls the size of
* the RCU grace period. So it needs to be upper-bound.
*/
-#define HUNG_TASK_BATCHING 1024
+#define HUNG_TASK_LOCK_BREAK (HZ / 10)
/*
* Zero means infinite timeout - no checking done:
@@ -171,7 +171,7 @@ static bool rcu_lock_break(struct task_struct *g, struct task_struct *t)
static void check_hung_uninterruptible_tasks(unsigned long timeout)
{
int max_count = sysctl_hung_task_check_count;
- int batch_count = HUNG_TASK_BATCHING;
+ unsigned long last_break = jiffies;
struct task_struct *g, *t;
/*
@@ -186,10 +186,10 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
for_each_process_thread(g, t) {
if (!max_count--)
goto unlock;
- if (!--batch_count) {
- batch_count = HUNG_TASK_BATCHING;
+ if (time_after(jiffies, last_break + HUNG_TASK_LOCK_BREAK)) {
if (!rcu_lock_break(g, t))
goto unlock;
+ last_break = jiffies;
}
/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
if (t->state == TASK_UNINTERRUPTIBLE)