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Date: Thu, 13 May 2021 14:30:23 -0700
From: Yang Shi <shy828301@...il.com>
To: Miaohe Lin <linmiaohe@...wei.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Zi Yan <ziy@...dia.com>,
william.kucharski@...cle.com, Matthew Wilcox <willy@...radead.org>,
Yang Shi <yang.shi@...ux.alibaba.com>,
aneesh.kumar@...ux.ibm.com, Ralph Campbell <rcampbell@...dia.com>,
Song Liu <songliubraving@...com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Rik van Riel <riel@...riel.com>,
Johannes Weiner <hannes@...xchg.org>,
Minchan Kim <minchan@...nel.org>,
Hugh Dickins <hughd@...gle.com>, adobriyan@...il.com,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux MM <linux-mm@...ck.org>,
Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v3 3/5] mm/huge_memory.c: add missing read-only THP
checking in transparent_hugepage_enabled()
On Tue, May 11, 2021 at 6:49 AM Miaohe Lin <linmiaohe@...wei.com> wrote:
>
> Since commit 99cb0dbd47a1 ("mm,thp: add read-only THP support for
> (non-shmem) FS"), read-only THP file mapping is supported. But it
> forgot to add checking for it in transparent_hugepage_enabled().
> To fix it, we add checking for read-only THP file mapping and also
> introduce helper transhuge_vma_enabled() to check whether thp is
> enabled for specified vma to reduce duplicated code. We rename
> transparent_hugepage_enabled to transparent_hugepage_active to make
> the code easier to follow as suggested by David Hildenbrand.
>
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Looks correct to me. Reviewed-by: Yang Shi <shy828301@...il.com>
Just a nit below:
> ---
> fs/proc/task_mmu.c | 2 +-
> include/linux/huge_mm.h | 27 ++++++++++++++++++++-------
> mm/huge_memory.c | 11 ++++++++++-
> mm/khugepaged.c | 4 +---
> mm/shmem.c | 3 +--
> 5 files changed, 33 insertions(+), 14 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index fc9784544b24..7389df326edd 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -832,7 +832,7 @@ static int show_smap(struct seq_file *m, void *v)
> __show_smap(m, &mss, false);
>
> seq_printf(m, "THPeligible: %d\n",
> - transparent_hugepage_enabled(vma));
> + transparent_hugepage_active(vma));
>
> if (arch_pkeys_enabled())
> seq_printf(m, "ProtectionKey: %8u\n", vma_pkey(vma));
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 0a526f211fec..a35c13d1f487 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -115,9 +115,19 @@ extern struct kobj_attribute shmem_enabled_attr;
>
> extern unsigned long transparent_hugepage_flags;
>
> +static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
I'd like to have this function defined next to transhuge_vma_suitable().
> + unsigned long vm_flags)
> +{
> + /* Explicitly disabled through madvise. */
> + if ((vm_flags & VM_NOHUGEPAGE) ||
> + test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
> + return false;
> + return true;
> +}
> +
> /*
> * to be used on vmas which are known to support THP.
> - * Use transparent_hugepage_enabled otherwise
> + * Use transparent_hugepage_active otherwise
> */
> static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
> {
> @@ -128,15 +138,12 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
> if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_NEVER_DAX))
> return false;
>
> - if (vma->vm_flags & VM_NOHUGEPAGE)
> + if (!transhuge_vma_enabled(vma, vma->vm_flags))
> return false;
>
> if (vma_is_temporary_stack(vma))
> return false;
>
> - if (test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
> - return false;
> -
> if (transparent_hugepage_flags & (1 << TRANSPARENT_HUGEPAGE_FLAG))
> return true;
>
> @@ -150,7 +157,7 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
> return false;
> }
>
> -bool transparent_hugepage_enabled(struct vm_area_struct *vma);
> +bool transparent_hugepage_active(struct vm_area_struct *vma);
>
> static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
> unsigned long haddr)
> @@ -351,7 +358,7 @@ static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)
> return false;
> }
>
> -static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> +static inline bool transparent_hugepage_active(struct vm_area_struct *vma)
> {
> return false;
> }
> @@ -362,6 +369,12 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
> return false;
> }
>
> +static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
> + unsigned long vm_flags)
> +{
> + return false;
> +}
> +
> static inline void prep_transhuge_page(struct page *page) {}
>
> static inline bool is_transparent_hugepage(struct page *page)
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 76ca1eb2a223..4f37867eed12 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -63,7 +63,14 @@ static struct shrinker deferred_split_shrinker;
> static atomic_t huge_zero_refcount;
> struct page *huge_zero_page __read_mostly;
>
> -bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> +static inline bool file_thp_enabled(struct vm_area_struct *vma)
> +{
> + return transhuge_vma_enabled(vma, vma->vm_flags) && vma->vm_file &&
> + !inode_is_open_for_write(vma->vm_file->f_inode) &&
> + (vma->vm_flags & VM_EXEC);
> +}
> +
> +bool transparent_hugepage_active(struct vm_area_struct *vma)
> {
> /* The addr is used to check if the vma size fits */
> unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
> @@ -74,6 +81,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> return __transparent_hugepage_enabled(vma);
> if (vma_is_shmem(vma))
> return shmem_huge_enabled(vma);
> + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS))
> + return file_thp_enabled(vma);
>
> return false;
> }
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 6c0185fdd815..d97b20fad6e8 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -442,9 +442,7 @@ static inline int khugepaged_test_exit(struct mm_struct *mm)
> static bool hugepage_vma_check(struct vm_area_struct *vma,
> unsigned long vm_flags)
> {
> - /* Explicitly disabled through madvise. */
> - if ((vm_flags & VM_NOHUGEPAGE) ||
> - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
> + if (!transhuge_vma_enabled(vma, vm_flags))
> return false;
>
> /* Enabled via shmem mount options or sysfs settings. */
> diff --git a/mm/shmem.c b/mm/shmem.c
> index a08cedefbfaa..1dcbec313c70 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -4032,8 +4032,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma)
> loff_t i_size;
> pgoff_t off;
>
> - if ((vma->vm_flags & VM_NOHUGEPAGE) ||
> - test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
> + if (!transhuge_vma_enabled(vma, vma->vm_flags))
> return false;
> if (shmem_huge == SHMEM_HUGE_FORCE)
> return true;
> --
> 2.23.0
>
>
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