On Tue, Oct 23 2018, Gi-Oh Kim wrote:
> On Wed, Oct 3, 2018 at 7:04 AM NeilBrown <neilb@xxxxxxxx> wrote:
>>
>>
>> Commit 35bfc52187f6 ("md: allow metadata update while suspending.")
>> added support for allowing md_check_recovery() to still perform
>> metadata updates while the array is entering the 'suspended' state.
>> This is needed to allow the processes of entering the state to
>> complete.
>>
>
> Hi,
>
> Could anybody please inform me how to test this patch?
You need to get mddev_suspend() to be called while mddev_lock() is held,
and for a metadata write to be triggered somewhere in there.
When the bug hits, you get a deadlock.
You can harmlessly trigger mddev_suspend() while holding the lock by
echo 0 > /sys/block/mdXX/md/suspend_hi
so maybe just doing that in a tight loop on an active array might be
enough.
>
> I would like to know how I can check "Commit 35bfc52187f6 ("md: allow
> metadata update while suspending.")" does not work
> and check this patch does work on my system.
> That is because there is a similar problem on my system.
> I would like to check that the problem on my system could be fixed by
> this patch.
>
>> Unfortunately, the patch doesn't really work. The test for
>
> Could you inform me what "The test" is?
>
void md_check_recovery(struct mddev *mddev)
{
if (mddev->suspended)
return;
That line of code where the "if" statement tests the value of
mddev->suspended - that is the "test" that I referred to.
NeilBrown
>> "mddev->suspended" at the start of md_check_recovery() means that the
>> function doesn't try to do anything at all while entering suspend.
>
>
> --
> GIOH KIM
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>
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