Re: [PATCH 1/2] init: Use GFP_NOWAIT for early slab allocations

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Fri, 2009-06-12 at 11:13 +0300, Pekka J Enberg wrote:
> From: Pekka Enberg <penberg@cs.helsinki.fi>
> 
> We setup slab allocators very early now while interrupts can still be disabled.
> Therefore, make sure call-sites that use slab_is_available() to switch to slab
> during boot use GFP_NOWAIT.
>
> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
> ---
> Ingo, Ben, can you confirm that x86 and powerpc work with these two 
> patches applied?

I'll have to test tomorrow, but I believe your patch 2/2 also misses
some cases, and in the end, 1/2 becomes completely unnecessary. I also
object to making vmalloc generally degrade to GFP_NOWAIT.

Again, what serious objection do you have against the patch I proposed ?

Cheers,
Ben.

>  include/linux/vmalloc.h |    1 +
>  kernel/params.c         |    2 +-
>  kernel/profile.c        |    6 +++---
>  mm/page_alloc.c         |    2 +-
>  mm/sparse-vmemmap.c     |    2 +-
>  mm/sparse.c             |    2 +-
>  mm/vmalloc.c            |   18 ++++++++++++++++++
>  7 files changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index a43ebec..7bcb9d7 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -53,6 +53,7 @@ static inline void vmalloc_init(void)
>  extern void *vmalloc(unsigned long size);
>  extern void *vmalloc_user(unsigned long size);
>  extern void *vmalloc_node(unsigned long size, int node);
> +extern void *vmalloc_node_boot(unsigned long size, int node);
>  extern void *vmalloc_exec(unsigned long size);
>  extern void *vmalloc_32(unsigned long size);
>  extern void *vmalloc_32_user(unsigned long size);
> diff --git a/kernel/params.c b/kernel/params.c
> index de273ec..5c239c3 100644
> --- a/kernel/params.c
> +++ b/kernel/params.c
> @@ -227,7 +227,7 @@ int param_set_charp(const char *val, struct kernel_param *kp)
>  	 * don't need to; this mangled commandline is preserved. */
>  	if (slab_is_available()) {
>  		kp->perm |= KPARAM_KMALLOCED;
> -		*(char **)kp->arg = kstrdup(val, GFP_KERNEL);
> +		*(char **)kp->arg = kstrdup(val, GFP_NOWAIT);
>  		if (!kp->arg)
>  			return -ENOMEM;
>  	} else
> diff --git a/kernel/profile.c b/kernel/profile.c
> index 28cf26a..86ada09 100644
> --- a/kernel/profile.c
> +++ b/kernel/profile.c
> @@ -112,16 +112,16 @@ int __ref profile_init(void)
>  	prof_len = (_etext - _stext) >> prof_shift;
>  	buffer_bytes = prof_len*sizeof(atomic_t);
>  
> -	if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
> +	if (!alloc_cpumask_var(&prof_cpu_mask, GFP_NOWAIT))
>  		return -ENOMEM;
>  
>  	cpumask_copy(prof_cpu_mask, cpu_possible_mask);
>  
> -	prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL);
> +	prof_buffer = kzalloc(buffer_bytes, GFP_NOWAIT);
>  	if (prof_buffer)
>  		return 0;
>  
> -	prof_buffer = alloc_pages_exact(buffer_bytes, GFP_KERNEL|__GFP_ZERO);
> +	prof_buffer = alloc_pages_exact(buffer_bytes, GFP_NOWAIT|__GFP_ZERO);
>  	if (prof_buffer)
>  		return 0;
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 17d5f53..7760ef9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2903,7 +2903,7 @@ int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
>  		 * To use this new node's memory, further consideration will be
>  		 * necessary.
>  		 */
> -		zone->wait_table = vmalloc(alloc_size);
> +		zone->wait_table = __vmalloc(alloc_size, GFP_NOWAIT, PAGE_KERNEL);
>  	}
>  	if (!zone->wait_table)
>  		return -ENOMEM;
> diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
> index a13ea64..9df6d99 100644
> --- a/mm/sparse-vmemmap.c
> +++ b/mm/sparse-vmemmap.c
> @@ -49,7 +49,7 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
>  	/* If the main allocator is up use that, fallback to bootmem. */
>  	if (slab_is_available()) {
>  		struct page *page = alloc_pages_node(node,
> -				GFP_KERNEL | __GFP_ZERO, get_order(size));
> +				GFP_NOWAIT | __GFP_ZERO, get_order(size));
>  		if (page)
>  			return page_address(page);
>  		return NULL;
> diff --git a/mm/sparse.c b/mm/sparse.c
> index da432d9..dd558d2 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -63,7 +63,7 @@ static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
>  				   sizeof(struct mem_section);
>  
>  	if (slab_is_available())
> -		section = kmalloc_node(array_size, GFP_KERNEL, nid);
> +		section = kmalloc_node(array_size, GFP_NOWAIT, nid);
>  	else
>  		section = alloc_bootmem_node(NODE_DATA(nid), array_size);
>  
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index f8189a4..3bec46d 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1559,6 +1559,24 @@ void *vmalloc_node(unsigned long size, int node)
>  }
>  EXPORT_SYMBOL(vmalloc_node);
>  
> +/**
> + *	vmalloc_node_boot  -  allocate memory on a specific node during boot
> + *	@size:		allocation size
> + *	@node:		numa node
> + *
> + *	Allocate enough pages to cover @size from the page level
> + *	allocator and map them into contiguous kernel virtual space.
> + *
> + *	For tight control over page level allocator and protection flags
> + *	use __vmalloc() instead.
> + */
> +void *vmalloc_node_boot(unsigned long size, int node)
> +{
> +	return __vmalloc_node(size, GFP_NOWAIT | __GFP_HIGHMEM, PAGE_KERNEL,
> +					node, __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(vmalloc_node_boot);
> +
>  #ifndef PAGE_KERNEL_EXEC
>  # define PAGE_KERNEL_EXEC PAGE_KERNEL
>  #endif

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