From: Dev Jain <dev.jain@arm.com>
To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org,
muchun.song@linux.dev, osalvador@suse.de
Cc: Dev Jain <dev.jain@arm.com>,
riel@surriel.com, liam@infradead.org, vbabka@kernel.org,
harry@kernel.org, jannh@google.com, lance.yang@linux.dev,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
ryan.roberts@arm.com, anshuman.khandual@arm.com
Subject: [PATCH v2 4/5] mm/rmap: refactor anon folio unmap in try_to_unmap_one
Date: Fri, 10 Jul 2026 05:59:13 +0000 [thread overview]
Message-ID: <20260710055915.638659-5-dev.jain@arm.com> (raw)
In-Reply-To: <20260710055915.638659-1-dev.jain@arm.com>
Refactor anonymous swapbacked folio unmap to ttu_anon_swapbacked_folio().
While at it, rename the remaining subpage variables to page; folios have
pages, not subpages.
No functional change intended.
Signed-off-by: Dev Jain <dev.jain@arm.com>
---
mm/rmap.c | 115 ++++++++++++++++++++++++++++++++----------------------
1 file changed, 68 insertions(+), 47 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index 4851c9f2a34e7..68459f23f5c0a 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2112,6 +2112,66 @@ static bool ttu_anon_lazyfree_folio(struct vm_area_struct *vma,
return true;
}
+static pte_t swp_pte_prepare(swp_entry_t entry, pte_t old_pte,
+ bool anon_exclusive)
+{
+ pte_t swp_pte = swp_entry_to_pte(entry);
+
+ if (anon_exclusive)
+ swp_pte = pte_swp_mkexclusive(swp_pte);
+
+ if (likely(pte_present(old_pte))) {
+ if (pte_soft_dirty(old_pte))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ if (pte_uffd_wp(old_pte))
+ swp_pte = pte_swp_mkuffd_wp(swp_pte);
+ } else {
+ /* Device-exclusive entry */
+ if (pte_swp_soft_dirty(old_pte))
+ swp_pte = pte_swp_mksoft_dirty(swp_pte);
+ if (pte_swp_uffd_wp(old_pte))
+ swp_pte = pte_swp_mkuffd_wp(swp_pte);
+ }
+
+ return swp_pte;
+}
+
+static bool ttu_anon_swapbacked_folio(struct vm_area_struct *vma,
+ struct folio *folio, struct page *page, unsigned long address,
+ pte_t *ptep, pte_t pteval)
+{
+ const bool anon_exclusive = folio_test_anon(folio) &&
+ PageAnonExclusive(page);
+ swp_entry_t entry = page_swap_entry(page);
+ struct mm_struct *mm = vma->vm_mm;
+
+ if (folio_dup_swap(folio, page) < 0)
+ return false;
+
+ /*
+ * arch_unmap_one() is expected to be a NOP on
+ * architectures where we could have PFN swap PTEs,
+ * so we'll not check/care.
+ */
+ if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+ folio_put_swap(folio, page);
+ return false;
+ }
+
+ /* See folio_try_share_anon_rmap(): clear PTE first. */
+ if (anon_exclusive && folio_try_share_anon_rmap_pte(folio, page)) {
+ folio_put_swap(folio, page);
+ return false;
+ }
+
+ mm_prepare_for_swap_entries(mm);
+ dec_mm_counter(mm, MM_ANONPAGES);
+ inc_mm_counter(mm, MM_SWAPENTS);
+ set_pte_at(mm, address, ptep,
+ swp_pte_prepare(entry, pteval, anon_exclusive));
+ return true;
+}
+
/*
* @arg: enum ttu_flags will be passed to this argument
*/
@@ -2120,9 +2180,9 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
{
struct mm_struct *mm = vma->vm_mm;
DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
- bool anon_exclusive, ret = true;
+ bool ret = true;
pte_t pteval;
- struct page *subpage;
+ struct page *page;
struct mmu_notifier_range range;
enum ttu_flags flags = (enum ttu_flags)(long)arg;
unsigned long nr_pages = 1, end_addr;
@@ -2233,9 +2293,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
pfn = softleaf_to_pfn(entry);
}
- subpage = folio_page(folio, pfn - folio_pfn(folio));
- anon_exclusive = folio_test_anon(folio) &&
- PageAnonExclusive(subpage);
+ page = folio_page(folio, pfn - folio_pfn(folio));
if (likely(pte_present(pteval))) {
nr_pages = folio_unmap_pte_batch(folio, &pvmw, flags, pteval);
@@ -2277,7 +2335,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
* folios here for now.
*/
if (folio_test_hwpoison(folio) && (flags & TTU_HWPOISON)) {
- pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
+ pteval = swp_entry_to_pte(make_hwpoison_entry(page));
dec_mm_counter(mm, mm_counter(folio));
set_pte_at(mm, address, pvmw.pte, pteval);
} else if (likely(pte_present(pteval)) && pte_unused(pteval) &&
@@ -2294,8 +2352,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
*/
dec_mm_counter(mm, mm_counter(folio));
} else if (folio_test_anon(folio)) {
- swp_entry_t entry = page_swap_entry(subpage);
- pte_t swp_pte;
/*
* Store the swap location in the pte.
* See handle_pte_fault() ...
@@ -2316,47 +2372,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
goto finish_unmap;
}
- if (folio_dup_swap(folio, subpage) < 0) {
- set_pte_at(mm, address, pvmw.pte, pteval);
- goto walk_abort;
- }
-
- /*
- * arch_unmap_one() is expected to be a NOP on
- * architectures where we could have PFN swap PTEs,
- * so we'll not check/care.
- */
- if (arch_unmap_one(mm, vma, address, pteval) < 0) {
- folio_put_swap(folio, subpage);
- set_pte_at(mm, address, pvmw.pte, pteval);
- goto walk_abort;
- }
-
- /* See folio_try_share_anon_rmap(): clear PTE first. */
- if (anon_exclusive &&
- folio_try_share_anon_rmap_pte(folio, subpage)) {
- folio_put_swap(folio, subpage);
+ if (!ttu_anon_swapbacked_folio(vma, folio, page, address,
+ pvmw.pte, pteval)) {
set_pte_at(mm, address, pvmw.pte, pteval);
goto walk_abort;
}
- mm_prepare_for_swap_entries(mm);
- dec_mm_counter(mm, MM_ANONPAGES);
- inc_mm_counter(mm, MM_SWAPENTS);
- swp_pte = swp_entry_to_pte(entry);
- if (anon_exclusive)
- swp_pte = pte_swp_mkexclusive(swp_pte);
- if (likely(pte_present(pteval))) {
- if (pte_soft_dirty(pteval))
- swp_pte = pte_swp_mksoft_dirty(swp_pte);
- if (pte_uffd_wp(pteval))
- swp_pte = pte_swp_mkuffd_wp(swp_pte);
- } else {
- if (pte_swp_soft_dirty(pteval))
- swp_pte = pte_swp_mksoft_dirty(swp_pte);
- if (pte_swp_uffd_wp(pteval))
- swp_pte = pte_swp_mkuffd_wp(swp_pte);
- }
- set_pte_at(mm, address, pvmw.pte, swp_pte);
+ goto finish_unmap;
} else {
/*
* This is a locked file-backed folio,
@@ -2372,7 +2393,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
add_mm_counter(mm, mm_counter_file(folio), -nr_pages);
}
finish_unmap:
- folio_remove_rmap_ptes(folio, subpage, nr_pages, vma);
+ folio_remove_rmap_ptes(folio, page, nr_pages, vma);
if (vma->vm_flags & VM_LOCKED)
mlock_drain_local();
folio_put_refs(folio, nr_pages);
--
2.43.0
next prev parent reply other threads:[~2026-07-10 5:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-10 5:59 [PATCH v2 0/5] mm/rmap: Refactor try_to_unmap_one Dev Jain
2026-07-10 5:59 ` [PATCH v2 1/5] mm/rmap: convert page -> folio for hwpoison checks Dev Jain
2026-07-10 12:22 ` David Hildenbrand (Arm)
2026-07-10 13:14 ` Dev Jain
2026-07-10 5:59 ` [PATCH v2 2/5] mm/rmap: Add try_to_unmap_hugetlb_one Dev Jain
2026-07-10 13:16 ` Dev Jain
2026-07-13 10:34 ` David Hildenbrand (Arm)
2026-07-13 12:11 ` Dev Jain
2026-07-10 5:59 ` [PATCH v2 3/5] mm/rmap: refactor some code around lazyfree folio unmapping Dev Jain
2026-07-10 5:59 ` Dev Jain [this message]
2026-07-10 5:59 ` [PATCH v2 5/5] mm/rmap: add anon folio unmap dispatcher Dev Jain
2026-07-10 12:27 ` David Hildenbrand (Arm)
2026-07-10 13:13 ` Dev Jain
2026-07-11 0:35 ` Andrew Morton
2026-07-11 12:14 ` Dev Jain
2026-07-12 11:47 ` David Hildenbrand (Arm)
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