On 02/07/2024 03:34, Bang Li wrote:
> After the commit 7fb1b252afb5 ("mm: shmem: add mTHP support for
> anonymous shmem"), we can configure different policies through
> the multi-size THP sysfs interface for anonymous shmem. But
> currently "THPeligible" indicates only whether the mapping is
> eligible for allocating THP-pages as well as the THP is PMD
> mappable or not for anonymous shmem, we need to support semantics
> for mTHP with anonymous shmem similar to those for mTHP with
> anonymous memory.
>
> Signed-off-by: Bang Li <libang.li@xxxxxxxxxxxx>
> ---
> Changes since v1 [1]:
> - Put anonymous shmem mthp related logic into
> thp_vma_allowable_orders() (per David)
>
> [1] https://lore.kernel.org/linux-mm/20240628104926.34209-1-libang.li@xxxxxxxxxxxx/
> ---
> include/linux/huge_mm.h | 11 +++++++++++
> mm/huge_memory.c | 13 +++++++++----
> mm/shmem.c | 9 +--------
> 3 files changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 212cca384d7e..f87136f38aa1 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -267,6 +267,10 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
> return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders);
> }
>
> +unsigned long shmem_allowable_huge_orders(struct inode *inode,
> + struct vm_area_struct *vma, pgoff_t index,
> + bool global_huge);
> +
> struct thpsize {
> struct kobject kobj;
> struct list_head node;
> @@ -460,6 +464,13 @@ static inline unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
> return 0;
> }
>
> +static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
> + struct vm_area_struct *vma, pgoff_t index,
> + bool global_huge)
> +{
> + return 0;
> +}
> +
> #define transparent_hugepage_flags 0UL
>
> #define thp_get_unmapped_area NULL
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index c7ce28f6b7f3..ea377bb4af91 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -151,10 +151,15 @@ 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))
> - return shmem_is_huge(file_inode(vma->vm_file), vma->vm_pgoff,
> - !enforce_sysfs, vma->vm_mm, vm_flags)
> - ? orders : 0;
> + if (!in_pf && shmem_file(vma->vm_file)) {
> + bool global_huge = shmem_is_huge(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;
nit: missing space before '?'
> + return shmem_allowable_huge_orders(file_inode(vma->vm_file),
> + vma, vma->vm_pgoff, global_huge);
What's the rationale for splitting these functions into shmem_is_huge() and
shmem_allowable_huge_orders()? Why not just have a single
shmem_allowable_huge_orders() that tells you the answer?
> + }
>
> if (!vma_is_anonymous(vma)) {
> /*
> diff --git a/mm/shmem.c b/mm/shmem.c
> index d495c0701a83..aa85df9c662a 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1622,7 +1622,7 @@ static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
> }
>
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -static unsigned long shmem_allowable_huge_orders(struct inode *inode,
> +unsigned long shmem_allowable_huge_orders(struct inode *inode,
> struct vm_area_struct *vma, pgoff_t index,
> bool global_huge)
> {
> @@ -1707,13 +1707,6 @@ static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault
> return orders;
> }
> #else
> -static unsigned long shmem_allowable_huge_orders(struct inode *inode,
> - struct vm_area_struct *vma, pgoff_t index,
> - bool global_huge)
> -{
> - return 0;
> -}
> -
> static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,
> struct address_space *mapping, pgoff_t index,
> unsigned long orders)
