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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 01.07.24 12:16, Ryan Roberts wrote: > On 01/07/2024 10:17, David Hildenbrand wrote: >> On 01.07.24 11:14, Ryan Roberts wrote: >>> On 01/07/2024 09:57, David Hildenbrand wrote: >>>> On 01.07.24 10:50, Ryan Roberts wrote: >>>>> 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 >>>>>>>>>> --- >>>>>>>>>>      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? >>>> >>>> I'm planning on looking into some details, especially the interaction with large >>>> folios in the pagecache. I'll let you know once I have a better idea what >>>> actually should be done :) >>> >>> OK great - I'll scrub it from my todo list... really getting things done today :) >> >> Resolved the khugepaged thiny already? :P >> >> [khugepaged not active when only enabling the sub-size via the 2M folder IIRC] > > Hmm... baby brain? :) I think I only mentioned it in a private mail at some point. > > Sorry about that. I've been a bit useless lately. For some reason it wasn't on > my list, but its there now. Will prioritise it, because I agree it's not good. IIRC, if you do echo never > /sys/kernel/mm/transparent_hugepage/enabled echo always > /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled khugepaged will not get activated. -- Cheers, David / dhildenb