[lkml]   [2012]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRE: hung_task checking and sys_sync
There   was  another  patch   addressing  these  type  of  issue .


-----Original Message-----
From: Mandeep Baines []
Sent: Tuesday, June 12, 2012 3:45 PM
To: Daniel Walker
Subject: Re: hung_task checking and sys_sync

On Tue, Jun 12, 2012 at 3:34 PM, Daniel Walker <> wrote:
> On Tue, Jun 12, 2012 at 03:29:12PM -0700, Mandeep Singh Baines wrote:
>> But the time is not unbounded. You could mask the hung_task_detector
>> for this case but then you lose the ability to catch bugs in this code
>> The timeout is configurable via
>> Can you bump up the value at boot via sysctl.conf?
> Maybe, but I'm wondering if these types should just be stopped because
> Andrew had complained about them already.

Fair enough. Actually, internally I had a patch where we'd use a task flag
to disable and enable the hang check but the approach in the patch you
pointed me to seems better.

>> > Has there been any commit that disable these messages bdi_sched_wait?
>> >
>> No. There is no mechanism to disable hung_task for a specific code
>> We do skip processes if PF_PROZEN or PF_FROZEN_SKIP is set but that
>> is really a different situation where the wait is unbounded.
> There is presidence for this type of change,
> Author: Mark Lord <>
> Date:   Fri Sep 24 09:51:13 2010 -0400
>    block: Prevent hang_check firing during long I/O
>    During long I/O operations, the hang_check timer may fire,
>    trigger stack dumps that unnecessarily alarm the user.
>    Eg.  hdparm --security-erase NULL /dev/sdb  ## can take *hours* to
> complete
>    So, if hang_check is armed, we should wake up periodically
>    to prevent it from triggering.  This patch uses a wake-up interval
>    equal to half the hang_check timer period, which keeps overhead low
>    Signed-off-by: Mark Lord <>
>    Signed-off-by: Jens Axboe <>

Interesting. I wasn't aware of this patch. Maybe we could abstract this
approach via wait_for_completion_no_hang_check().

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2012-06-13 05:41    [W:0.090 / U:4.884 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site