Hey Zi, David, How about this change(diff against mm-unstable) as follows? I'd like to add __try_to_unmap_huge_pmd() as a new internal function specifically for unmapping PMD-mapped folios. If, for any reason, we cannot unmap the folio, then we'll still split it as previously done. Currently, __try_to_unmap_huge_pmd() only handles lazyfree THPs, but it can be extended to support other large folios that are PMD-mapped in the future if needed. diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 670218f762c8..0f906dc6d280 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -100,8 +100,6 @@ enum ttu_flags { * do a final flush if necessary */ TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock: * caller holds it */ - TTU_LAZYFREE_THP = 0x100, /* avoid splitting PMD-mapped THPs - * that are marked as lazyfree. */ }; #ifdef CONFIG_MMU diff --git a/mm/rmap.c b/mm/rmap.c index a7913a454028..879c8923abfc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1606,6 +1606,19 @@ void folio_remove_rmap_pmd(struct folio *folio, struct page *page, #endif } +static bool __try_to_unmap_huge_pmd(struct vm_area_struct *vma, + unsigned long addr, struct folio *folio) +{ + VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) + return discard_trans_pmd(vma, addr, folio); +#endif + + return false; +} + /* * @arg: enum ttu_flags will be passed to this argument */ @@ -1631,14 +1644,11 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, if (flags & TTU_SYNC) pvmw.flags = PVMW_SYNC; -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (flags & TTU_LAZYFREE_THP) - if (discard_trans_pmd(vma, address, folio)) + if (flags & TTU_SPLIT_HUGE_PMD) { + if (__try_to_unmap_huge_pmd(vma, address, folio)) return true; -#endif - - if (flags & TTU_SPLIT_HUGE_PMD) split_huge_pmd_address(vma, address, false, folio); + } /* * For THP, we have to assume the worse case ie pmd for invalidation. diff --git a/mm/vmscan.c b/mm/vmscan.c index e2686cc0c037..49bd94423961 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1277,13 +1277,6 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, if (folio_test_pmd_mappable(folio)) flags |= TTU_SPLIT_HUGE_PMD; - -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - if (folio_test_anon(folio) && !was_swapbacked && - (flags & TTU_SPLIT_HUGE_PMD)) - flags |= TTU_LAZYFREE_THP; -#endif - /* * Without TTU_SYNC, try_to_unmap will only begin to * hold PTL from the first present PTE within a large -- Thanks, Lance