Commit 15bde4ab authored by Barry Song's avatar Barry Song Committed by Andrew Morton
Browse files

mm: extend rmap flags arguments for folio_add_new_anon_rmap 

Patch series "mm: clarify folio_add_new_anon_rmap() and
__folio_add_anon_rmap()", v2.

This patchset is preparatory work for mTHP swapin.

folio_add_new_anon_rmap() assumes that new anon rmaps are always
exclusive.  However, this assumption doesn’t hold true for cases like
do_swap_page(), where a new anon might be added to the swapcache and is
not necessarily exclusive.

The patchset extends the rmap flags to allow folio_add_new_anon_rmap() to
handle both exclusive and non-exclusive new anon folios.  The
do_swap_page() function is updated to use this extended API with rmap
flags.  Consequently, all new anon folios now consistently use
folio_add_new_anon_rmap().  The special case for !folio_test_anon() in
__folio_add_anon_rmap() can be safely removed.

In conclusion, new anon folios always use folio_add_new_anon_rmap(),
regardless of exclusivity.  Old anon folios continue to use
__folio_add_anon_rmap() via folio_add_anon_rmap_pmd() and
folio_add_anon_rmap_ptes().


This patch (of 3):

In the case of a swap-in, a new anonymous folio is not necessarily
exclusive.  This patch updates the rmap flags to allow a new anonymous
folio to be treated as either exclusive or non-exclusive.  To maintain the
existing behavior, we always use EXCLUSIVE as the default setting.

[akpm@linux-foundation.org: cleanup and constifications per David and akpm]
[v-songbaohua@oppo.com: fix missing doc for flags of folio_add_new_anon_rmap()]
  Link: https://lkml.kernel.org/r/20240619210641.62542-1-21cnbao@gmail.com
[v-songbaohua@oppo.com: enhance doc for extend rmap flags arguments for folio_add_new_anon_rmap]
  Link: https://lkml.kernel.org/r/20240622030256.43775-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240617231137.80726-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240617231137.80726-2-21cnbao@gmail.com


Signed-off-by: default avatarBarry Song <v-songbaohua@oppo.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Tested-by: default avatarShuai Yuan <yuanshuai@oppo.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 55ccad6f

include/linux/rmap.h

+1 −1
Original line number Diff line number Diff line
@@ -244,7 +244,7 @@ void folio_add_anon_rmap_ptes(struct folio *, struct page *, int nr_pages, 
void folio_add_anon_rmap_pmd(struct folio *, struct page *,

		struct vm_area_struct *, unsigned long address, rmap_t flags);

void folio_add_new_anon_rmap(struct folio *, struct vm_area_struct *,

		unsigned long address);

		unsigned long address, rmap_t flags);

void folio_add_file_rmap_ptes(struct folio *, struct page *, int nr_pages,

		struct vm_area_struct *);

#define folio_add_file_rmap_pte(folio, page, vma) \

kernel/events/uprobes.c

+1 −1
Original line number Diff line number Diff line
@@ -181,7 +181,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 


	if (new_page) {

		folio_get(new_folio);

		folio_add_new_anon_rmap(new_folio, vma, addr);

		folio_add_new_anon_rmap(new_folio, vma, addr, RMAP_EXCLUSIVE);

		folio_add_lru_vma(new_folio, vma);

	} else

		/* no new page, just dec_mm_counter for old_page */

mm/huge_memory.c

+1 −1
Original line number Diff line number Diff line
@@ -974,7 +974,7 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf, 


		entry = mk_huge_pmd(page, vma->vm_page_prot);

		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);

		folio_add_new_anon_rmap(folio, vma, haddr);

		folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);

		folio_add_lru_vma(folio, vma);

		pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);

		set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);

mm/khugepaged.c

+1 −1
Original line number Diff line number Diff line
@@ -1210,7 +1210,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, 


	spin_lock(pmd_ptl);

	BUG_ON(!pmd_none(*pmd));

	folio_add_new_anon_rmap(folio, vma, address);

	folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);

	folio_add_lru_vma(folio, vma);

	pgtable_trans_huge_deposit(mm, pmd, pgtable);

	set_pmd_at(mm, address, pmd, _pmd);

mm/memory.c

+5 −5
Original line number Diff line number Diff line
@@ -930,7 +930,7 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma 
	*prealloc = NULL;

	copy_user_highpage(&new_folio->page, page, addr, src_vma);

	__folio_mark_uptodate(new_folio);

	folio_add_new_anon_rmap(new_folio, dst_vma, addr);

	folio_add_new_anon_rmap(new_folio, dst_vma, addr, RMAP_EXCLUSIVE);

	folio_add_lru_vma(new_folio, dst_vma);

	rss[MM_ANONPAGES]++;
@@ -3402,7 +3402,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) 
		 * some TLBs while the old PTE remains in others.

		 */

		ptep_clear_flush(vma, vmf->address, vmf->pte);

		folio_add_new_anon_rmap(new_folio, vma, vmf->address);

		folio_add_new_anon_rmap(new_folio, vma, vmf->address, RMAP_EXCLUSIVE);

		folio_add_lru_vma(new_folio, vma);

		BUG_ON(unshare && pte_write(entry));

		set_pte_at(mm, vmf->address, vmf->pte, entry);
@@ -4339,7 +4339,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) 


	/* ksm created a completely new copy */

	if (unlikely(folio != swapcache && swapcache)) {

		folio_add_new_anon_rmap(folio, vma, address);

		folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);

		folio_add_lru_vma(folio, vma);

	} else {

		folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
@@ -4594,7 +4594,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) 
#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC);

#endif

	folio_add_new_anon_rmap(folio, vma, addr);

	folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);

	folio_add_lru_vma(folio, vma);

setpte:

	if (vmf_orig_pte_uffd_wp(vmf))
@@ -4792,7 +4792,7 @@ void set_pte_range(struct vm_fault *vmf, struct folio *folio, 
	/* copy-on-write page */

	if (write && !(vma->vm_flags & VM_SHARED)) {

		VM_BUG_ON_FOLIO(nr != 1, folio);

		folio_add_new_anon_rmap(folio, vma, addr);

		folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);

		folio_add_lru_vma(folio, vma);

	} else {

		folio_add_file_rmap_ptes(folio, page, nr, vma);