Messages in this thread Patch in this message | | | From | Miaohe Lin <> | Subject | [PATCH 2/7] mm/khugepaged: stop swapping in page when VM_FAULT_RETRY occurs | Date | Sat, 11 Jun 2022 16:47:26 +0800 |
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When do_swap_page returns VM_FAULT_RETRY, we do not retry here and thus swap entry will remain in pagetable. This will result in later failure. So stop swapping in pages in this case to save cpu cycles.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- mm/khugepaged.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 73570dfffcec..a8adb2d1e9c6 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1003,19 +1003,16 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, swapped_in++; ret = do_swap_page(&vmf); - /* do_swap_page returns VM_FAULT_RETRY with released mmap_lock */ + /* + * do_swap_page returns VM_FAULT_RETRY with released mmap_lock. + * Note we treat VM_FAULT_RETRY as VM_FAULT_ERROR here because + * we do not retry here and swap entry will remain in pagetable + * resulting in later failure. + */ if (ret & VM_FAULT_RETRY) { mmap_read_lock(mm); - if (hugepage_vma_revalidate(mm, haddr, &vma)) { - /* vma is no longer available, don't continue to swapin */ - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); - return false; - } - /* check if the pmd is still valid */ - if (mm_find_pmd(mm, haddr) != pmd) { - trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); - return false; - } + trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); + return false; } if (ret & VM_FAULT_ERROR) { trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 0); -- 2.23.0
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