Commit 29f252cd authored by Barry Song's avatar Barry Song Committed by Andrew Morton
Browse files

mm: introduce arch_do_swap_page_nr() which allows restore metadata for nr pages 

Should do_swap_page() have the capability to directly map a large folio,
metadata restoration becomes necessary for a specified number of pages
denoted as nr.  It's important to highlight that metadata restoration is
solely required by the SPARC platform, which, however, does not enable
THP_SWAP.  Consequently, in the present kernel configuration, there exists
no practical scenario where users necessitate the restoration of nr
metadata.  Platforms implementing THP_SWAP might invoke this function with
nr values exceeding 1, subsequent to do_swap_page() successfully mapping
an entire large folio.  Nonetheless, their arch_do_swap_page_nr()
functions remain empty.

Link: https://lkml.kernel.org/r/20240529082824.150954-5-21cnbao@gmail.com


Signed-off-by: default avatarBarry Song <v-songbaohua@oppo.com>
Reviewed-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Reviewed-by: default avatarKhalid Aziz <khalid.aziz@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gao Xiang <xiang@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3f9abcaa

include/linux/pgtable.h

+20 −6
Original line number Diff line number Diff line
@@ -1089,6 +1089,15 @@ static inline int pgd_same(pgd_t pgd_a, pgd_t pgd_b) 
})



#ifndef __HAVE_ARCH_DO_SWAP_PAGE

static inline void arch_do_swap_page_nr(struct mm_struct *mm,

				     struct vm_area_struct *vma,

				     unsigned long addr,

				     pte_t pte, pte_t oldpte,

				     int nr)

{



}

#else

/*

 * Some architectures support metadata associated with a page. When a

 * page is being swapped out, this metadata must be saved so it can be
@@ -1097,12 +1106,17 @@ static inline int pgd_same(pgd_t pgd_a, pgd_t pgd_b) 
 * page as metadata for the page. arch_do_swap_page() can restore this

 * metadata when a page is swapped back in.

 */

static inline void arch_do_swap_page(struct mm_struct *mm,

static inline void arch_do_swap_page_nr(struct mm_struct *mm,

					struct vm_area_struct *vma,

					unsigned long addr,

				     pte_t pte, pte_t oldpte)

					pte_t pte, pte_t oldpte,

					int nr)

{



	for (int i = 0; i < nr; i++) {

		arch_do_swap_page(vma->vm_mm, vma, addr + i * PAGE_SIZE,

				pte_advance_pfn(pte, i),

				pte_advance_pfn(oldpte, i));

	}

}

#endif

mm/memory.c

+2 −1
Original line number Diff line number Diff line
@@ -4308,7 +4308,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 
	VM_BUG_ON(!folio_test_anon(folio) ||

			(pte_write(pte) && !PageAnonExclusive(page)));

	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);

	arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);

	arch_do_swap_page_nr(vma->vm_mm, vma, vmf->address,

			pte, vmf->orig_pte, 1);



	folio_unlock(folio);

	if (folio != swapcache && swapcache) {