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How often does it happen? >>> Are there particular workloads that benefit from this? (I'm not sure >>> what "mutil backed-applications" are?) >> 1 Yes, this patch has been tested. >> >> 2 When the exiting tasks and shrink_inactive_list occur at the same time, >>    the folios which shrink_inactive_list reclaims may be the exiting tasks's >> folios >>    in lruvecs. And when system is low memory, it more likely to occur, >> because >>    more backend applidatuions will be killed. >>    The shrink_inactive_list reclaims the exiting tasks's folios in lruvecs >> and >>    transforms the exiting tasks's anon folios into swap memory, which leads >>    to the increasing load of the current exiting tasks. > Ah, we're talking about an OOM scenario. OK, that makes some sense. > You should have mentioned that in the patch description. Hi, 1 Ok, I will update a more comprehensive description in next version. 2 I think this issue can occur not only in OOM scenario, but also in   normal task exit scenario. So: 1) if (unlikely(!atomic_read(&vma->vm_mm->mm_users))) represents   the scenario where the task exits normally. 2) if(test_bit(MMF_OOM_SKIP, &vma->vm_mm->flags)) represents the    OOM Reaper scenario. 3 MMF_OOM_SKIP can only represent OOM scenario and cannot represent   normal task exit scenario, as when MMF_OOM_SKIP is set in normal   task exit scenario, the memory folios of the task have already been   released. And the shrink_inactive_list should recognize these lru folios   in exiting task before this exiting task releases its memory folios.     tlb_gather_mmu_fullmm(&tlb, mm);     /* update_hiwater_rss(mm) here? but nobody should be looking */     /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */     unmap_vmas(&tlb, &mas, vma, 0, ULONG_MAX, ULONG_MAX, false);     mmap_read_unlock(mm);     /*      * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper      * because the memory has been already freed.      */     set_bit(MMF_OOM_SKIP, &mm->flags); >> 3 This patch can alleviate the load of the tasks exiting process. This patch >>    can make that the exiting tasks release its anon folios faster instead of >>    releasing its swap memory from its anon folios swap-in in >> shrink_inactive_list. >> >> 4 "mutil backed-applications" means that there are a large number of >>     the backend applications in the system. >> >> Thanks >>> And I do mean specifically of this patch, because to my eyes it >>> shouldn't even compile. >> Has been tested. > That's odd. I thought GCC used to complain about > > long x = 0x100000000; > > but it does the right thing. Except on 32-bit where it'll say > "warning: integer constant out of range". > > In any case, the number you chose is not going to work on 32-bit systems > or on ARM or x86. It conflicts with protection keys on x86 and MTE on > ARM. You're right, I overlooked the situation with the 32-bit system. > We can do it without any new magic numbers. I'm not sure this is a > great approach, but this should work: > > +++ b/mm/rmap.c > @@ -840,6 +840,12 @@ static bool folio_referenced_one(struct folio *folio, > int referenced = 0; > unsigned long start = address, ptes = 0; > > + /* Skip this folio if it's mapped by an exiting task */ > + if (test_bit(MMF_OOM_SKIP, &vma->vm_mm->flags)) { > + pra->referenced = -1; > + return false; > + } > + > while (page_vma_mapped_walk(&pvmw)) { > address = pvmw.address; > I agree with your point of view. I think this is currently the best solution,   but I think it also needs to be added with: if (unlikely(!atomic_read(&vma->vm_mm->mm_users))) Please help review it again. Best Regards.