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Date: Thu, 31 Mar 2022 00:26:07 +0000
From: Song Liu <songliubraving@...com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"song@...nel.org" <song@...nel.org>,
"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
"x86@...nel.org" <x86@...nel.org>,
"daniel@...earbox.net" <daniel@...earbox.net>,
"andrii@...nel.org" <andrii@...nel.org>,
Kernel Team <Kernel-team@...com>,
"pmenzel@...gen.mpg.de" <pmenzel@...gen.mpg.de>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"ast@...nel.org" <ast@...nel.org>
Subject: Re: [PATCH bpf 2/4] vmalloc: introduce HAVE_ARCH_HUGE_VMALLOC_FLAG
> On Mar 30, 2022, at 4:40 PM, Edgecombe, Rick P <rick.p.edgecombe@...el.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@...nel.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;
>>
>> /*
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