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SubjectRe: [RFC PATCH 2/2] lib: debugobjects: touch watchdog to avoid softlockup when !CONFIG_PREEMPT
On 11/27/2017 12:54 PM, Yang Shi wrote:
> Hi Waiman,
> The second patch of this series.
> Thanks,
> Yang
> On 11/17/17 11:43 AM, Yang Shi wrote:
>> There are nested loops on debug objects free path, sometimes it may take
>> over hundred thousands of loops, then cause soft lockup with
>> occasionally, like below:
>> ...
>> The code path might be called in either atomic or non-atomic context,
>> so touching softlockup watchdog instead of calling cond_resched() which
>> might fall asleep. However, it is unnecessary to touch the watchdog
>> every loop, so just touch the watchdog at every 10000 (best estimate)
>> loops.
>> Signed-off-by: Yang Shi <>

I do have some concern about suppressing the soft lockup warning
entirely. If the system feels unresponsive for a certain period of time
(e.g. 22s), most users would like to know what is going on. It can be a
custom message with less scary warning. Alternatively, some opt-out
mechanism can be added to explicitly disable soft lookup warning for
debugobjs is OK as long as it is not the default.


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