The patch titled
Subject: swap: avoid a redundant pte map if ra window is 1
has been added to the -mm mm-unstable branch. Its filename is
swap-avoid-a-redundant-pte-map-if-ra-window-is-1.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/swap-avoid-a-redundant-pte-map-if-ra-window-is-1.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kairui Song <kasong@xxxxxxxxxxx>
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@xxxxxxxxx
Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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)
_
Patches currently in -mm which might be from kasong@xxxxxxxxxxx are
swapfile-get-rid-of-volatile-and-avoid-redundant-read.patch
swap-avoid-a-redundant-pte-map-if-ra-window-is-1.patch
swap-fold-swap_ra_clamp_pfn-into-swap_ra_info.patch
swap-avoid-holding-swap-reference-in-swap_cache_get_folio.patch
