| From: Kairui Song <kasong@tencent.com> |
| Subject: swap: avoid a redundant pte map if ra window is 1 |
| Date: Tue, 20 Dec 2022 02:58:38 +0800 |
| |
| Avoid a redundant pte map/unmap when swap readahead window is 1. |
| |
| Link: https://lkml.kernel.org/r/20221219185840.25441-3-ryncsn@gmail.com |
| Signed-off-by: Kairui Song <kasong@tencent.com> |
| Reviewed-by: "Huang, Ying" <ying.huang@intel.com> |
| Cc: David Hildenbrand <david@redhat.com> |
| Cc: Hugh Dickins <hughd@google.com> |
| Cc: Matthew Wilcox (Oracle) <willy@infradead.org> |
| Cc: Miaohe Lin <linmiaohe@huawei.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| mm/swap_state.c | 7 ++----- |
| 1 file changed, 2 insertions(+), 5 deletions(-) |
| |
| --- a/mm/swap_state.c~swap-avoid-a-redundant-pte-map-if-ra-window-is-1 |
| +++ a/mm/swap_state.c |
| @@ -727,8 +727,6 @@ static void swap_ra_info(struct vm_fault |
| } |
| |
| faddr = vmf->address; |
| - orig_pte = pte = pte_offset_map(vmf->pmd, faddr); |
| - |
| fpfn = PFN_DOWN(faddr); |
| ra_val = GET_SWAP_RA_VAL(vma); |
| pfn = PFN_DOWN(SWAP_RA_ADDR(ra_val)); |
| @@ -739,12 +737,11 @@ static void swap_ra_info(struct vm_fault |
| atomic_long_set(&vma->swap_readahead_info, |
| SWAP_RA_VAL(faddr, win, 0)); |
| |
| - if (win == 1) { |
| - pte_unmap(orig_pte); |
| + if (win == 1) |
| return; |
| - } |
| |
| /* Copy the PTEs because the page table may be unmapped */ |
| + orig_pte = pte = pte_offset_map(vmf->pmd, faddr); |
| if (fpfn == pfn + 1) |
| swap_ra_clamp_pfn(vma, faddr, fpfn, fpfn + win, &start, &end); |
| else if (pfn == fpfn + 1) |
| _ |
