Re: [BUG] Lockdep recursive locking in kmem_cache_free
From: Christoph Lameter
Date: Fri Jul 28 2006 - 17:24:41 EST
On Fri, 28 Jul 2006, Ravikiran G Thirumalai wrote:
> Why should there be any problem taking the remote l3 lock? If the remote
> node does not have cpu that does not mean we cannot take a lock from the
> local node!!!
>
> I think current git does not teach lockdep to ignore recursion for
> array_cache->lock when the array_cache->lock are from different cases. As
> Arjan pointed out, I can see that l3->list_lock is special cased, but I
> cannot find where array_cache->lock is taken care of.
Ok.
> Again, if this is indeed a problem (recursion) machine should not boot even,
> when compiled without lockdep, tglx, can you please verify this?
We seem to be fine on that level.
I would still like to see someone thinking through this a bit more.
Allocations via page_alloc_node() may be redirected by cpusets and
because nodes are low on memory. This means that we get memory on a
different node than we requested. How does that impact the alien lock
situation? In particular what happens if the off slab allocation for
the management object was on a different node from the slab data?
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