From: Lance Yang Let's skip unsuitable VMAs early in the khugepaged scan; specifically, mlocked VMAs should not be touched. Note that the only other user of the VM_NO_KHUGEPAGED mask is __thp_vma_allowable_orders(), which is also used by the MADV_COLLAPSE path. Since MADV_COLLAPSE has different rules (e.g., for mlocked VMAs), we cannot simply make the shared mask stricter as that would break it. So, we also introduce a new VM_NO_THP_COLLAPSE mask for that helper, leaving the stricter checks to be applied only within the khugepaged path itself. Signed-off-by: Lance Yang --- include/linux/mm.h | 6 +++++- mm/huge_memory.c | 2 +- mm/khugepaged.c | 14 +++++++++++++- 3 files changed, 19 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index be3e6fb4d0db..cb54d94b2343 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -505,7 +505,11 @@ extern unsigned int kobjsize(const void *objp); #define VM_REMAP_FLAGS (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP) /* This mask prevents VMA from being scanned with khugepaged */ -#define VM_NO_KHUGEPAGED (VM_SPECIAL | VM_HUGETLB) +#define VM_NO_KHUGEPAGED \ + (VM_SPECIAL | VM_HUGETLB | VM_LOCKED_MASK | VM_NOHUGEPAGE) + +/* This mask prevents VMA from being collapsed by any THP path */ +#define VM_NO_THP_COLLAPSE (VM_SPECIAL | VM_HUGETLB) /* This mask defines which mm->def_flags a process can inherit its parent */ #define VM_INIT_DEF_MASK VM_NOHUGEPAGE diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d6fc669e11c1..2e91526a037f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -134,7 +134,7 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, * Must be checked after dax since some dax mappings may have * VM_MIXEDMAP set. */ - if (!in_pf && !smaps && (vm_flags & VM_NO_KHUGEPAGED)) + if (!in_pf && !smaps && (vm_flags & VM_NO_THP_COLLAPSE)) return 0; /* diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 7c5ff1b23e93..e54f99bb0b57 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -345,6 +345,17 @@ struct attribute_group khugepaged_attr_group = { }; #endif /* CONFIG_SYSFS */ +/** + * khugepaged_should_scan_vma - check if a VMA is a candidate for collapse + * @vm_flags: The flags of the VMA to check. + * + * Returns: true if the VMA should be scanned by khugepaged, false otherwise. + */ +static inline bool khugepaged_should_scan_vma(vm_flags_t vm_flags) +{ + return !(vm_flags & VM_NO_KHUGEPAGED); +} + int hugepage_madvise(struct vm_area_struct *vma, vm_flags_t *vm_flags, int advice) { @@ -2443,7 +2454,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, progress++; break; } - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { + if (!khugepaged_should_scan_vma(vma->vm_flags) || + !thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { skip: progress++; continue; -- 2.49.0