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Message-ID: <b670b981-bc79-4c8c-8b69-4879300066d4@arm.com>
Date: Mon, 15 Jul 2024 14:36:41 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org,
hughd@...gle.com
Cc: willy@...radead.org, david@...hat.com, 21cnbao@...il.com, ziy@...dia.com,
ioworker0@...il.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] mm: shmem: move shmem_huge_global_enabled() into
shmem_allowable_huge_orders()
On 13/07/2024 14:24, Baolin Wang wrote:
> Move shmem_huge_global_enabled() into the shmem_allowable_huge_orders() function,
> so that shmem_allowable_huge_orders() can also help to find the allowable huge
> orders for tmpfs. Moreover the shmem_huge_global_enabled() can become static.
>
> No functional changes.
>
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
one nit below, but either way:
Reviewed-by: Ryan Roberts <ryan.roberts@....com>
> ---
> include/linux/shmem_fs.h | 12 ++----------
> mm/huge_memory.c | 12 +++---------
> mm/shmem.c | 41 ++++++++++++++++++++++++++--------------
> 3 files changed, 32 insertions(+), 33 deletions(-)
>
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index 405ee8d3589a..1564d7d3ca61 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -111,21 +111,13 @@ extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
> int shmem_unuse(unsigned int type);
>
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -extern bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index, bool shmem_huge_force,
> - struct mm_struct *mm, unsigned long vm_flags);
> unsigned long shmem_allowable_huge_orders(struct inode *inode,
> struct vm_area_struct *vma, pgoff_t index,
> - bool global_huge);
> + bool shmem_huge_force);
> #else
> -static __always_inline bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
> - bool shmem_huge_force, struct mm_struct *mm,
> - unsigned long vm_flags)
> -{
> - return false;
> -}
> static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
> struct vm_area_struct *vma, pgoff_t index,
> - bool global_huge)
> + bool shmem_huge_force)
> {
> return 0;
> }
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index cc9bad12be75..f69980b5b5fc 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -151,16 +151,10 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
> * Must be done before hugepage flags check since shmem has its
> * own flags.
> */
> - if (!in_pf && shmem_file(vma->vm_file)) {
> - bool global_huge = shmem_huge_global_enabled(file_inode(vma->vm_file),
> - vma->vm_pgoff, !enforce_sysfs,
> - vma->vm_mm, vm_flags);
> -
> - if (!vma_is_anon_shmem(vma))
> - return global_huge ? orders : 0;
> + if (!in_pf && shmem_file(vma->vm_file))
> return shmem_allowable_huge_orders(file_inode(vma->vm_file),
> - vma, vma->vm_pgoff, global_huge);
> - }
> + vma, vma->vm_pgoff,
> + !enforce_sysfs);
>
> if (!vma_is_anonymous(vma)) {
> /*
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 1445dcd39b6f..4d274f5a17d9 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -581,7 +581,7 @@ static bool __shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
> }
> }
>
> -bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
> +static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
> bool shmem_huge_force, struct mm_struct *mm,
> unsigned long vm_flags)
> {
> @@ -772,6 +772,13 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
> {
> return 0;
> }
> +
> +static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
> + bool shmem_huge_force, struct mm_struct *mm,
> + unsigned long vm_flags)
> +{
> + return false;
> +}
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>
> /*
> @@ -1625,27 +1632,39 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> unsigned long shmem_allowable_huge_orders(struct inode *inode,
> struct vm_area_struct *vma, pgoff_t index,
> - bool global_huge)
> + bool shmem_huge_force)
> {
> unsigned long mask = READ_ONCE(huge_shmem_orders_always);
> unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
> - unsigned long vm_flags = vma->vm_flags;
> + unsigned long vm_flags = vma ? vma->vm_flags : 0;
> + struct mm_struct *fault_mm = vma ? vma->vm_mm : NULL;
nit: rather than deriving the fault_mm here, I wonder if its cleaner to just
pass vma to shmem_huge_global_enabled()? shmem_huge_global_enabled() is just
using it as a guard to access vm_flags, which you can just as easily do by
testing the vma for non-NULL. And you can access mm flags with vma->vm_mm->flags
after testing the vma too.
> /*
> * Check all the (large) orders below HPAGE_PMD_ORDER + 1 that
> * are enabled for this vma.
> */
> unsigned long orders = BIT(PMD_ORDER + 1) - 1;
> + bool global_huge;
> loff_t i_size;
> int order;
>
> - if ((vm_flags & VM_NOHUGEPAGE) ||
> - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
> + if (vma && ((vm_flags & VM_NOHUGEPAGE) ||
> + test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
> return 0;
>
> /* If the hardware/firmware marked hugepage support disabled. */
> if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_UNSUPPORTED))
> return 0;
>
> + global_huge = shmem_huge_global_enabled(inode, index, shmem_huge_force,
> + fault_mm, vm_flags);
> + if (!vma || !vma_is_anon_shmem(vma)) {
> + /*
> + * For tmpfs, we now only support PMD sized THP if huge page
> + * is enabled, otherwise fallback to order 0.
> + */
> + return global_huge ? BIT(HPAGE_PMD_ORDER) : 0;
> + }
> +
> /*
> * Following the 'deny' semantics of the top level, force the huge
> * option off from all mounts.
> @@ -2081,7 +2100,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> struct mm_struct *fault_mm;
> struct folio *folio;
> int error;
> - bool alloced, huge;
> + bool alloced;
> unsigned long orders = 0;
>
> if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
> @@ -2154,14 +2173,8 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
> return 0;
> }
>
> - huge = shmem_huge_global_enabled(inode, index, false, fault_mm,
> - vma ? vma->vm_flags : 0);
> - /* Find hugepage orders that are allowed for anonymous shmem. */
> - if (vma && vma_is_anon_shmem(vma))
> - orders = shmem_allowable_huge_orders(inode, vma, index, huge);
> - else if (huge)
> - orders = BIT(HPAGE_PMD_ORDER);
> -
> + /* Find hugepage orders that are allowed for anonymous shmem and tmpfs. */
> + orders = shmem_allowable_huge_orders(inode, vma, index, false);
> if (orders > 0) {
> gfp_t huge_gfp;
>
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