Re: [PATCH bpf 2/4] vmalloc: introduce HAVE_ARCH_HUGE_VMALLOC_FLAG

[Song Liu <songliubraving@fb.com>]

> On Mar 30, 2022, at 4:40 PM, Edgecombe, Rick P <rick.p.edgecombe@intel.com> wrote:
> 
> On Wed, 2022-03-30 at 15:56 -0700, Song Liu wrote:
>> With HAVE_ARCH_HUGE_VMALLOC_FLAG, users of __vmalloc_node_range()
>> could
>> use VM_TRY_HUGE_VMAP to (try to) allocate PMD_SIZE pages for
>> size >= PMD_SIZE cases. Similar to HAVE_ARCH_HUGE_VMALLOC, the use
>> can
>> disable huge page by specifying nohugeiomap in kernel command line.
>> 
>> The first user of VM_TRY_HUGE_VMAP will be bpf_prog_pack.
>> 
>> Signed-off-by: Song Liu <song@kernel.org>
>> ---
>> arch/Kconfig            |  9 +++++++++
>> include/linux/vmalloc.h |  9 +++++++--
>> mm/vmalloc.c            | 28 +++++++++++++++++++---------
>> 3 files changed, 35 insertions(+), 11 deletions(-)
>> 
>> diff --git a/arch/Kconfig b/arch/Kconfig
>> index 33e06966f248..23b6e92aebaa 100644
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -864,6 +864,15 @@ config HAVE_ARCH_HUGE_VMALLOC
>> 	depends on HAVE_ARCH_HUGE_VMAP
>> 	bool
>> 
>> +#
>> +# HAVE_ARCH_HUGE_VMALLOC_FLAG allows users of __vmalloc_node_range
>> to allocate
>> +# huge page without HAVE_ARCH_HUGE_VMALLOC. To allocate huge pages,
>> the user
>> +# need to call __vmalloc_node_range with VM_TRY_HUGE_VMAP.
>> +#
>> +config HAVE_ARCH_HUGE_VMALLOC_FLAG
>> +	depends on HAVE_ARCH_HUGE_VMAP
>> +	bool
>> +
>> config ARCH_WANT_HUGE_PMD_SHARE
>> 	bool
>> 
>> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
>> index 3b1df7da402d..a48d0690b66f 100644
>> --- a/include/linux/vmalloc.h
>> +++ b/include/linux/vmalloc.h
>> @@ -35,6 +35,11 @@ struct notifier_block;		/* in
>> notifier.h */
>> #define VM_DEFER_KMEMLEAK	0
>> #endif
>> 
>> +#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG
>> +#define VM_TRY_HUGE_VMAP	0x00001000	/* Allow for huge
>> pages on HAVE_ARCH_HUGE_VMALLOC_FLAG arch's */
>> +#else
>> +#define VM_TRY_HUGE_VMAP	0
>> +#endif
>> /* bits [20..32] reserved for arch specific ioremap internals */
>> 
>> /*
>> @@ -51,7 +56,7 @@ struct vm_struct {
>> 	unsigned long		size;
>> 	unsigned long		flags;
>> 	struct page		**pages;
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
>> 	unsigned int		page_order;
>> #endif
>> 	unsigned int		nr_pages;
>> @@ -225,7 +230,7 @@ static inline bool is_vm_area_hugepages(const
>> void *addr)
>> 	 * prevents that. This only indicates the size of the physical
>> page
>> 	 * allocated in the vmalloc layer.
>> 	 */
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
> 
> Since HAVE_ARCH_HUGE_VMALLOC_FLAG depends on HAVE_ARCH_HUGE_VMAP, I
> don't think you need both here.

I think we still need this one (_VMALLOC || _VMALLOC_FLAG)? 
Note that this is not _VMAP || _VMALLOC_FLAG. 

> 
>> 	return find_vm_area(addr)->page_order > 0;
>> #else
>> 	return false;
>> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
>> index e163372d3967..179200bce285 100644
>> --- a/mm/vmalloc.c
>> +++ b/mm/vmalloc.c
>> @@ -46,7 +46,7 @@
>> #include "internal.h"
>> #include "pgalloc-track.h"
>> 
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
> 
> Same as above.

And this one could be just CONFIG_HAVE_ARCH_HUGE_VMAP?

> 
>> static unsigned int __ro_after_init ioremap_max_page_shift =
>> BITS_PER_LONG - 1;
>> 
>> static int __init set_nohugeiomap(char *str)
>> @@ -55,11 +55,11 @@ static int __init set_nohugeiomap(char *str)
>> 	return 0;
>> }
>> early_param("nohugeiomap", set_nohugeiomap);
>> -#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
>> +#else /* CONFIG_HAVE_ARCH_HUGE_VMAP ||
>> CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG */
>> static const unsigned int ioremap_max_page_shift = PAGE_SHIFT;
>> -#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
>> +#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP ||
>> CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG*/
> 
> Same here, and for the rest below. I think having
> HAVE_ARCH_HUGE_VMALLOC_FLAG depend on HAVE_ARCH_HUGE_VMAP like you did
> is nice because you don't need to special logic for most of the huge
> page parts. It should shrink this patch.
> 
>> 
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || 
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
>> static bool __ro_after_init vmap_allow_huge = true;
>> 
>> static int __init set_nohugevmalloc(char *str)
>> @@ -582,8 +582,9 @@ int vmap_pages_range_noflush(unsigned long addr,
>> unsigned long end,
>> 
>> 	WARN_ON(page_shift < PAGE_SHIFT);
>> 
>> -	if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> -			page_shift == PAGE_SHIFT)
>> +	if ((!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) &&
>> +	     !IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG)) ||
>> +	    (page_shift == PAGE_SHIFT))
>> 		return vmap_small_pages_range_noflush(addr, end, prot,
>> pages);
>> 
>> 	for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) {
>> @@ -2252,7 +2253,7 @@ static struct vm_struct *vmlist __initdata;
>> 
>> static inline unsigned int vm_area_page_order(struct vm_struct *vm)
>> {
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
>> 	return vm->page_order;
>> #else
>> 	return 0;
>> @@ -2261,7 +2262,7 @@ static inline unsigned int
>> vm_area_page_order(struct vm_struct *vm)
>> 
>> static inline void set_vm_area_page_order(struct vm_struct *vm,
>> unsigned int order)
>> {
>> -#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
>> +#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
>> defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
>> 	vm->page_order = order;
>> #else
>> 	BUG_ON(order != 0);
>> @@ -3056,6 +3057,15 @@ static void *__vmalloc_area_node(struct
>> vm_struct *area, gfp_t gfp_mask,
>> 	return NULL;
>> }
>> 
>> +static bool vmalloc_try_huge_page(unsigned long vm_flags)
>> +{
>> +	if (!vmap_allow_huge || (vm_flags & VM_NO_HUGE_VMAP))
>> +		return false;
>> +
>> +	/* VM_TRY_HUGE_VMAP only works for
>> CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG */
>> +	return vm_flags & VM_TRY_HUGE_VMAP;
>> +}
>> +
> 
> It won't return true in the case of just CONFIG_HAVE_ARCH_HUGE_VMALLOC
> and vmap_allow_huge. If you have CONFIG_HAVE_ARCH_HUGE_VMALLOC, but not
> CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG like powerpc, it should still try
> huge pages like before.

Yeah, I missed this one.. Will fix in the next version. 

> 
>> /**
>>  * __vmalloc_node_range - allocate virtually contiguous memory
>>  * @size:		  allocation size
>> @@ -3106,7 +3116,7 @@ void *__vmalloc_node_range(unsigned long size,
>> unsigned long align,
>> 		return NULL;
>> 	}
>> 
>> -	if (vmap_allow_huge && !(vm_flags & VM_NO_HUGE_VMAP)) {
>> +	if (vmalloc_try_huge_page(vm_flags)) {
>> 		unsigned long size_per_node;
>> 
>> 		/*