* [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" [not found] <1394089669-18285-1-git-send-email-sdu.liu@huawei.com> @ 2014-03-06 7:19 ` Liu hua 2014-03-06 15:35 ` Paul Gortmaker 0 siblings, 1 reply; 3+ messages in thread From: Liu hua @ 2014-03-06 7:19 UTC (permalink / raw) To: Ingo Molnar; +Cc: oleg, paul.gortmaker, Li Zefan, Wang Nan, linux-kernel As sysctl_hung_task_timeout_sec is unsigned long, when this value is larger then LONG_MAX, the function schedule_timeout_interruptible in watchdog will return immediately without sleep : for example (in x86_64 platform): linux# echo 0xFFFFFFFFFFFFFFFF > /proc/sys/kernel/hung_task_timeout_secs [ 66.798350] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.800064] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.801774] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.803488] schedule_timeout: wrong timeout value ffffffffffffff06 [ 66.805225] schedule_timeout: wrong timeout value ffffffffffffff06 The screen was filled with "schedule_timeout: wrong timeout value ffffffffffffff06" and the system stalled. So I do some check and correction in timeout_jiffies, to let the function schedule_timeout_interruptible allways get the valid parameter. Signed-off-by: Liu Hua <sdu.liu@huawei.com> --- kernel/hung_task.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index 06bb141..ef96650 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -186,7 +186,16 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) static unsigned long timeout_jiffies(unsigned long timeout) { /* timeout of 0 will disable the watchdog */ - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) { + pr_err("%s : wrong timeout value %lx\n", + __func__, timeout); + pr_err("Timeout value is set to MAX_SCHEDULE_TIMEOUT(%lx) now.\n", + MAX_SCHEDULE_TIMEOUT); + return MAX_SCHEDULE_TIMEOUT; + } + + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ? + timeout * HZ : MAX_SCHEDULE_TIMEOUT; } /* -- 1.8.5.5.dirty . ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" 2014-03-06 7:19 ` [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" Liu hua @ 2014-03-06 15:35 ` Paul Gortmaker 2014-03-10 3:34 ` Liu hua 0 siblings, 1 reply; 3+ messages in thread From: Paul Gortmaker @ 2014-03-06 15:35 UTC (permalink / raw) To: Liu hua, Ingo Molnar; +Cc: oleg, Li Zefan, Wang Nan, linux-kernel On 14-03-06 02:19 AM, Liu hua wrote: > As sysctl_hung_task_timeout_sec is unsigned long, when this value is > larger then LONG_MAX, the function schedule_timeout_interruptible in > watchdog will return immediately without sleep : > > for example (in x86_64 platform): > > linux# echo 0xFFFFFFFFFFFFFFFF > /proc/sys/kernel/hung_task_timeout_secs > > [ 66.798350] schedule_timeout: wrong timeout value ffffffffffffff06 > [ 66.800064] schedule_timeout: wrong timeout value ffffffffffffff06 > [ 66.801774] schedule_timeout: wrong timeout value ffffffffffffff06 > [ 66.803488] schedule_timeout: wrong timeout value ffffffffffffff06 > [ 66.805225] schedule_timeout: wrong timeout value ffffffffffffff06 > > The screen was filled with "schedule_timeout: wrong timeout value > ffffffffffffff06" and the system stalled. > > So I do some check and correction in timeout_jiffies, to let the function > schedule_timeout_interruptible allways get the valid parameter. > > Signed-off-by: Liu Hua <sdu.liu@huawei.com> > --- > kernel/hung_task.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/kernel/hung_task.c b/kernel/hung_task.c > index 06bb141..ef96650 100644 > --- a/kernel/hung_task.c > +++ b/kernel/hung_task.c > @@ -186,7 +186,16 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > static unsigned long timeout_jiffies(unsigned long timeout) > { > /* timeout of 0 will disable the watchdog */ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ You are breaking the above functionality/feature by declaring zero invalid. Paul. -- > - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; > + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) { > + pr_err("%s : wrong timeout value %lx\n", > + __func__, timeout); > + pr_err("Timeout value is set to MAX_SCHEDULE_TIMEOUT(%lx) now.\n", > + MAX_SCHEDULE_TIMEOUT); > + return MAX_SCHEDULE_TIMEOUT; > + } > + > + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ? > + timeout * HZ : MAX_SCHEDULE_TIMEOUT; > } > > /* > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" 2014-03-06 15:35 ` Paul Gortmaker @ 2014-03-10 3:34 ` Liu hua 0 siblings, 0 replies; 3+ messages in thread From: Liu hua @ 2014-03-10 3:34 UTC (permalink / raw) To: Paul Gortmaker, Ingo Molnar; +Cc: oleg, Li Zefan, Wang Nan, linux-kernel on 2014/3/6 23:35, Paul Gortmaker wrote: > On 14-03-06 02:19 AM, Liu hua wrote: >> As sysctl_hung_task_timeout_sec is unsigned long, when this value is >> larger then LONG_MAX, the function schedule_timeout_interruptible in >> watchdog will return immediately without sleep : >> >> for example (in x86_64 platform): >> >> linux# echo 0xFFFFFFFFFFFFFFFF > /proc/sys/kernel/hung_task_timeout_secs >> >> [ 66.798350] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.800064] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.801774] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.803488] schedule_timeout: wrong timeout value ffffffffffffff06 >> [ 66.805225] schedule_timeout: wrong timeout value ffffffffffffff06 >> >> The screen was filled with "schedule_timeout: wrong timeout value >> ffffffffffffff06" and the system stalled. >> >> So I do some check and correction in timeout_jiffies, to let the function >> schedule_timeout_interruptible allways get the valid parameter. >> >> Signed-off-by: Liu Hua <sdu.liu@huawei.com> >> --- >> kernel/hung_task.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/hung_task.c b/kernel/hung_task.c >> index 06bb141..ef96650 100644 >> --- a/kernel/hung_task.c >> +++ b/kernel/hung_task.c >> @@ -186,7 +186,16 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) >> static unsigned long timeout_jiffies(unsigned long timeout) >> { >> /* timeout of 0 will disable the watchdog */ > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > You are breaking the above functionality/feature by declaring > zero invalid. > > Paul. > -- > Actually the patch will disable the watchdog if the timeout is illegal(except 0) for schedule_timeout_interruptible. I will make a new patch that disables the watchdog when the timeout is 0 or above LONG_MAX without printing errors ? What do you think? Liu Hua >> - return timeout ? timeout * HZ : MAX_SCHEDULE_TIMEOUT; >> + if ((timeout == 0) || (timeout > MAX_SCHEDULE_TIMEOUT)) { >> + pr_err("%s : wrong timeout value %lx\n", >> + __func__, timeout); >> + pr_err("Timeout value is set to MAX_SCHEDULE_TIMEOUT(%lx) now.\n", >> + MAX_SCHEDULE_TIMEOUT); >> + return MAX_SCHEDULE_TIMEOUT; >> + } >> + >> + return (timeout * HZ) < MAX_SCHEDULE_TIMEOUT ? >> + timeout * HZ : MAX_SCHEDULE_TIMEOUT; >> } >> >> /* >> > > . > ^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <1394089669-18285-1-git-send-email-sdu.liu@huawei.com>
2014-03-06 7:19 ` [PATCH] hung_task : check the value of "sysctl_hung_task_timeout_sec" Liu hua
2014-03-06 15:35 ` Paul Gortmaker
2014-03-10 3:34 ` Liu hua
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