On Wed, 7 May 2014 14:19:19 -0700 (PDT) David Rientjes <rientjes@xxxxxxxxxx> 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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