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Date: Wed, 30 Mar 2022 23:40:18 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "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>
CC: "daniel@...earbox.net" <daniel@...earbox.net>,
"andrii@...nel.org" <andrii@...nel.org>,
"kernel-team@...com" <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 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.
> 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.
> 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.
> /**
> * __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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