Re: [PATCH] support "THPeligible" semantics for mTHP with anonymous shmem

David Hildenbrand
2024-07-01T06:57:43Z

On 28.06.24 12:49, 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@antgroup.com>
> ---
> fs/proc/task_mmu.c | 10 +++++++---
> include/linux/huge_mm.h | 11 +++++++++++
> mm/shmem.c | 9 +--------
> 3 files changed, 19 insertions(+), 11 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 93fb2c61b154..09b5db356886 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -870,6 +870,7 @@ static int show_smap(struct seq_file *m, void *v)
> {
> struct vm_area_struct *vma = v;
> struct mem_size_stats mss = {};
> + bool thp_eligible;
>
> smap_gather_stats(vma, &mss, 0);
>
> @@ -882,9 +883,12 @@ static int show_smap(struct seq_file *m, void *v)
>
> __show_smap(m, &mss, false);
>
> - seq_printf(m, "THPeligible: %8u\n",
> - !!thp_vma_allowable_orders(vma, vma->vm_flags,
> - TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL));
> + thp_eligible = !!thp_vma_allowable_orders(vma, vma->vm_flags,
> + TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL);
> + if (vma_is_anon_shmem(vma))
> + thp_eligible = !!shmem_allowable_huge_orders(file_inode(vma->vm_file),
> + vma, vma->vm_pgoff, thp_eligible);

I would have thought the correct fix is to return the correct result
from thp_vma_allowable_orders().

--
Cheers,

David / dhildenb