Re: + shmem-fix-faulting-into-a-hole-while-its-punched-take-2.patch added to -mm tree

From: Hugh Dickins
Date: Fri Jul 11 2014 - 10:57:35 EST


On Fri, 11 Jul 2014, Sasha Levin wrote:
>
> There's no easy way to see whether a given task is actually holding a lock or
> is just blocking on it without going through all those tasks one by one and
> looking at their trace.
>
> I agree with you that "The call trace is very clear on it that its not", but
> when you have 500 call traces you really want something better than going
> through it one call trace at a time.

Points well made, and I strongly agree with Vlastimil and Sasha.
There is a world of difference between a lock wanted and a lock held,
and for the display of locks "held" to conceal that difference is unhelpful.
It just needs one greppable word to distinguish the cases.

(Though I didn't find "The call trace is very clear on it that its not",
I thought it too was telling me that the lock was already held somehow.)

Hugh
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