Commit 18ad72f5 authored by Kairui Song's avatar Kairui Song Committed by Andrew Morton
Browse files

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: default avatarKairui Song <kasong@tencent.com>
Reviewed-by: default avatar"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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3f79b187

mm/swap_state.c

+2 −5
Original line number Diff line number Diff line
@@ -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)