* [PATCH] softlockup: fix to allow compiling with !DETECT_HUNG_TASK
@ 2009-01-16 17:09 Mandeep Singh Baines
2009-01-16 17:18 ` Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Mandeep Singh Baines @ 2009-01-16 17:09 UTC (permalink / raw
To: mingo, linux-kernel; +Cc: hannes, rientjes, mbligh, thockin
Ingo Molnar (mingo@elte.hu) wrote:
>
> doesnt build with !SOFTLOCKUP:
>
> kernel/fork.c:1049: error: 'struct task_struct' has no member named 'last_switch_count'
> kernel/fork.c:1050: error: 'struct task_struct' has no member named 'last_switch_timestamp'
>
> Could you send a delta fix patch relative to -v4 please? Thanks,
>
> Ingo
Oops. Will be more careful next time.
---
Fixes the following compile error:
kernel/fork.c:1049: error: 'struct task_struct' has no member named 'last_switch_count'
kernel/fork.c:1050: error: 'struct task_struct' has no member named 'last_switch_timestamp'
Signed-off-by: Mandeep Singh Baines <msb@google.com>
---
kernel/fork.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index fb1f5e9..d68e59b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1045,7 +1045,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->default_timer_slack_ns = current->timer_slack_ns;
-#ifdef CONFIG_DETECT_SOFTLOCKUP
+#ifdef CONFIG_DETECT_HUNG_TASK
p->last_switch_count = 0;
p->last_switch_timestamp = 0;
#endif
--
1.5.4.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] softlockup: fix to allow compiling with !DETECT_HUNG_TASK
2009-01-16 17:09 [PATCH] softlockup: fix to allow compiling with !DETECT_HUNG_TASK Mandeep Singh Baines
@ 2009-01-16 17:18 ` Ingo Molnar
2009-01-17 18:31 ` [PATCH] softlockup: fix potential race in hung_task when resetting timeout Mandeep Singh Baines
0 siblings, 1 reply; 4+ messages in thread
From: Ingo Molnar @ 2009-01-16 17:18 UTC (permalink / raw
To: Mandeep Singh Baines; +Cc: linux-kernel, hannes, rientjes, mbligh, thockin
* Mandeep Singh Baines <msb@google.com> wrote:
> Ingo Molnar (mingo@elte.hu) wrote:
> >
> > doesnt build with !SOFTLOCKUP:
> >
> > kernel/fork.c:1049: error: 'struct task_struct' has no member named 'last_switch_count'
> > kernel/fork.c:1050: error: 'struct task_struct' has no member named 'last_switch_timestamp'
> >
> > Could you send a delta fix patch relative to -v4 please? Thanks,
> >
> > Ingo
>
> Oops. Will be more careful next time.
np - applied to tip/core/softlockup. Thanks,
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] softlockup: fix potential race in hung_task when resetting timeout
2009-01-16 17:18 ` Ingo Molnar
@ 2009-01-17 18:31 ` Mandeep Singh Baines
2009-01-18 18:22 ` Ingo Molnar
0 siblings, 1 reply; 4+ messages in thread
From: Mandeep Singh Baines @ 2009-01-17 18:31 UTC (permalink / raw
To: Ingo Molnar; +Cc: linux-kernel, hannes, rientjes, mbligh, thockin
Patch against tip/core/softlockup.
---
A potential race exists if sysctl_hung_task_timeout_secs is reset to 0
while inside check_hung_uniterruptible_tasks(). If check_task() is
entered, a comparison with 0 will result in a false hung_task being
detected.
If sysctl_hung_task_panic is set, the system will panic.
Signed-off-by: Mandeep Singh Baines <msb@google.com>
---
kernel/hung_task.c | 24 ++++++++++++++++--------
1 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index ba5a77c..ba8ccd4 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -72,7 +72,8 @@ static unsigned long get_timestamp(void)
return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
}
-static void check_hung_task(struct task_struct *t, unsigned long now)
+static void check_hung_task(struct task_struct *t, unsigned long now,
+ unsigned long timeout)
{
unsigned long switch_count = t->nvcsw + t->nivcsw;
@@ -84,8 +85,7 @@ static void check_hung_task(struct task_struct *t, unsigned long now)
t->last_switch_timestamp = now;
return;
}
- if ((long)(now - t->last_switch_timestamp) <
- sysctl_hung_task_timeout_secs)
+ if ((long)(now - t->last_switch_timestamp) < timeout)
return;
if (!sysctl_hung_task_warnings)
return;
@@ -96,8 +96,7 @@ static void check_hung_task(struct task_struct *t, unsigned long now)
* complain:
*/
printk(KERN_ERR "INFO: task %s:%d blocked for more than "
- "%ld seconds.\n", t->comm, t->pid,
- sysctl_hung_task_timeout_secs);
+ "%ld seconds.\n", t->comm, t->pid, timeout);
printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
" disables this message.\n");
sched_show_task(t);
@@ -115,7 +114,7 @@ static void check_hung_task(struct task_struct *t, unsigned long now)
* a really long time (120 seconds). If that happens, print out
* a warning.
*/
-static void check_hung_uninterruptible_tasks(void)
+static void check_hung_uninterruptible_tasks(unsigned long timeout)
{
int max_count = sysctl_hung_task_check_count;
unsigned long now = get_timestamp();
@@ -134,7 +133,7 @@ static void check_hung_uninterruptible_tasks(void)
goto unlock;
/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
if (t->state == TASK_UNINTERRUPTIBLE)
- check_hung_task(t, now);
+ check_hung_task(t, now, timeout);
} while_each_thread(g, t);
unlock:
read_unlock(&tasklist_lock);
@@ -180,8 +179,17 @@ static int watchdog(void *dummy)
update_poll_jiffies();
for ( ; ; ) {
+ unsigned long timeout;
+
while (schedule_timeout_interruptible(hung_task_poll_jiffies));
- check_hung_uninterruptible_tasks();
+
+ /*
+ * Need to cache timeout here to avoid timeout being set
+ * to 0 via sysctl while inside check_hung_*_tasks().
+ */
+ timeout = sysctl_hung_task_timeout_secs;
+ if (timeout)
+ check_hung_uninterruptible_tasks(timeout);
}
return 0;
--
1.5.4.5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] softlockup: fix potential race in hung_task when resetting timeout
2009-01-17 18:31 ` [PATCH] softlockup: fix potential race in hung_task when resetting timeout Mandeep Singh Baines
@ 2009-01-18 18:22 ` Ingo Molnar
0 siblings, 0 replies; 4+ messages in thread
From: Ingo Molnar @ 2009-01-18 18:22 UTC (permalink / raw
To: Mandeep Singh Baines; +Cc: linux-kernel, hannes, rientjes, mbligh, thockin
* Mandeep Singh Baines <msb@google.com> wrote:
> Patch against tip/core/softlockup.
>
> ---
>
> A potential race exists if sysctl_hung_task_timeout_secs is reset to 0
> while inside check_hung_uniterruptible_tasks(). If check_task() is
> entered, a comparison with 0 will result in a false hung_task being
> detected.
>
> If sysctl_hung_task_panic is set, the system will panic.
>
> Signed-off-by: Mandeep Singh Baines <msb@google.com>
> ---
> kernel/hung_task.c | 24 ++++++++++++++++--------
> 1 files changed, 16 insertions(+), 8 deletions(-)
Applied to tip/core/softlockup, thanks Mandeep!
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2009-01-18 18:22 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2009-01-16 17:09 [PATCH] softlockup: fix to allow compiling with !DETECT_HUNG_TASK Mandeep Singh Baines
2009-01-16 17:18 ` Ingo Molnar
2009-01-17 18:31 ` [PATCH] softlockup: fix potential race in hung_task when resetting timeout Mandeep Singh Baines
2009-01-18 18:22 ` Ingo Molnar
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