Messages in this thread | | | Date | Wed, 7 May 2014 14:29:25 -0700 | From | Andrew Morton <> | Subject | Re: [patch] mm, slab: suppress out of memory warning unless debug is enabled |
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On Wed, 7 May 2014 14:19:19 -0700 (PDT) David Rientjes <rientjes@google.com> wrote:
> When the slab or slub allocators cannot allocate additional slab pages, they > emit diagnostic information to the kernel log such as current number of slabs, > number of objects, active objects, etc. This is always coupled with a page > allocation failure warning since it is controlled by !__GFP_NOWARN. > > Suppress this out of memory warning if the allocator is configured without debug > supported. The page allocation failure warning will indicate it is a failed > slab allocation, so this is only useful to diagnose allocator bugs. > > Since CONFIG_SLUB_DEBUG is already enabled by default for the slub allocator, > there is no functional change with this patch. If debug is disabled, however, > the warnings are now suppressed. >
I'm not seeing any reason for making this change.
> @@ -1621,11 +1621,17 @@ __initcall(cpucache_init); > static noinline void > slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid) > { > +#if DEBUG > struct kmem_cache_node *n; > struct page *page; > unsigned long flags; > int node; > > + if (gfpflags & __GFP_NOWARN) > + return; > + if (!printk_ratelimit()) > + return;
printk_ratelimit() is lame - it uses a single global state. So if random net driver is using printk_ratelimit(), that driver and slab will interfere with each other.
We don't appear to presently have a handy macro to do this properly - you might care to add one and switch printk_ratelimited() and pr_debug_ratelimited() over to using it. And various sites in include/linux/device.h, I guess.
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