Re: [PATCH] kasan: convert kasan/quarantine_lock to raw_spinlock
From: Sebastian Andrzej Siewior
Date: Tue Oct 09 2018 - 10:27:50 EST
On 2018-10-08 11:15:57 [+0200], Dmitry Vyukov wrote:
> Hi Sebastian,
> This seems to beak quarantine_remove_cache( ) in the sense that some
> object from the cache may still be in quarantine when
> quarantine_remove_cache() returns. When quarantine_remove_cache()
> returns all objects from the cache must be purged from quarantine.
> That srcu and irq trickery is there for a reason.
That loop should behave like your on_each_cpu() except it does not
involve the remote CPU.
> This code is also on hot path of kmallock/kfree, an additional
> lock/unlock per operation is expensive. Adding 2 locked RMW per
> kmalloc is not something that should be done only out of refactoring
But this is debug code anyway, right? And it is highly complex imho.
Well, maybe only for me after I looked at it for the first timeâ
> The original message from Clark mentions that the problem can be fixed
> by just changing type of spinlock. This looks like a better and
> simpler way to resolve the problem to me.
I usually prefer to avoid adding raw_locks everywhere if it can be
avoided. However given that this is debug code and a few additional us
shouldn't matter here, I have no problem with Clark's initial patch
(also the mem-free in irq-off region works in this scenario).
Can you take it as-is or should I repost it with an acked-by?