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swap: avoid a redundant pte map if ra window is 1 

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>
This commit is contained in:
Kairui Song 2022-12-20 02:58:38 +08:00 committed by Andrew Morton
parent 3f79b187ad
commit 18ad72f5b7
1 changed files with 2 additions and 5 deletions
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7
mm/swap_state.c
View File

@ -727,8 +727,6 @@ static void swap_ra_info(struct vm_fault *vmf,
}
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 *vmf,
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)