On Wed, Jul 20, 2011 at 08:54:10AM -0500, Christoph Lameter wrote:

On Wed, 20 Jul 2011, Pekka Enberg wrote:

quoted

On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:

quoted

quoted

The changelog isn't that convincing, really. This is kmem_cache_create()
so I'm surprised we'd ever get NULL here in practice. Does this fix some
problem you're seeing? If this is really an issue, I'd blame the page
allocator as GFP_KERNEL should just work.

nf_conntrack creates separate slab-cache for each net-namespace,
this patch of course not eliminates the chance of failure, but makes it more
acceptable.

I'm still surprised you are seeing failures. mm/slab.c hasn't changed
significantly in a long time. Why hasn't anyone reported this before? I'd
still be inclined to shift the blame to the page allocator... Mel, Christoph?

There was a lot of recent fiddling with the reclaim logic. Maybe some of
those changes caused the problem?

It's more likely that creating new slabs while under memory pressure
significant enough to fail an order-4 allocation is a situation that is
rarely tested. 

What kernel version did this failure occur on? What was the system doing
at the time of failure? Can the page allocation failure message be
posted?

-- 
Mel Gorman
SUSE Labs

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>