Re: [PATCH] mm:Avoid soft lockup due to possible attempt of double locking object's lock in __delete_object

Rik van Riel
2016-09-07T00:45:24Z

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On Wed, 2016-08-31 at 09:24 -0400, nick wrote:
>
> On 2016-08-31 03:54 AM, Catalin Marinas wrote:
> > On Tue, Aug 30, 2016 at 02:35:12PM -0400, Nicholas Krause wrote:
> > > This fixes a issue in the current locking logic of the function,
> > > __delete_object where we are trying to attempt to lock the passed
> > > object structure's spinlock again after being previously held
> > > elsewhere by the kmemleak code. Fix this by instead of assuming
> > > we are the only one contending for the object's lock their are
> > > possible other users and create two branches, one where we get
> > > the lock when calling spin_trylock_irqsave on the object's lock
> > > and the other when the lock is held else where by kmemleak.
> >
> > Have you actually got a deadlock that requires this fix?
> >
> Yes I have got a deadlock that this does fix.

Why don't you share the backtrace with us?

Claiming you have a deadlock, but not sharing
it on the list means nobody can see what the
problem is you are trying to address.

It would be good if every email with a patch
that you post starts with an actual detailed
problem description.

Can you do that?