On 01/07/2024 09:48, David Hildenbrand wrote:
> On 01.07.24 10:40, Ryan Roberts wrote:
>> On 01/07/2024 09:33, Baolin Wang wrote:
>>>
>>>
>>> On 2024/7/1 15:55, Ryan Roberts wrote:
>>>> On 28/06/2024 11:49, 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@xxxxxxxxxxxx>
>>>>> ---
>>>>> 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);
>>>>
>>>> Afraid I haven't been following the shmem mTHP support work as much as I would
>>>> have liked, but is there a reason why we need a separate function for shmem?
>>>
>>> Since shmem_allowable_huge_orders() only uses shmem specific logic to determine
>>> if huge orders are allowable, there is no need to complicate the
>>> thp_vma_allowable_orders() function by adding more shmem related logic, making
>>> it more bloated. In my view, providing a dedicated helper
>>> shmem_allowable_huge_orders(), specifically for shmem, simplifies the logic.
>>
>> My point was really that a single interface (thp_vma_allowable_orders) should be
>> used to get this information. I have no strong opinon on how the implementation
>> of that interface looks. What you suggest below seems perfectly reasonable to me.
>
> Right. thp_vma_allowable_orders() might require some care as discussed in other
> context (cleanly separate dax and shmem handling/orders). But that would be
> follow-up cleanups.
Are you planning to do that, or do you want me to send a patch?
