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mm/rmap: refactor anon folio unmap in try_to_unmap_one

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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.

Link: https://lore.kernel.org/20260730094559.418003-5-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dev Jain
2026-07-30 09:45:55 +00:00
committed by Andrew Morton
parent 0955037b98
commit 0caf74274d
1 changed files with 68 additions and 47 deletions
Download Patch File Download Diff File Expand all files Collapse all files

115
mm/rmap.c
View File

@@ -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(old_pte))
swp_pte = pte_swp_mkuffd(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(old_pte))
swp_pte = pte_swp_mkuffd(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);
@@ -2274,7 +2332,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
/* unmap_poisoned_folio() only refs order-0 folios */
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) &&
@@ -2291,8 +2349,6 @@ 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() ...
@@ -2313,47 +2369,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
goto finish_unmap;
}
if (folio_dup_swap(folio, subpage) < 0) {
if (!ttu_anon_swapbacked_folio(vma, folio, page, address,
pvmw.pte, pteval)) {
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);
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(pteval))
swp_pte = pte_swp_mkuffd(swp_pte);
} else {
if (pte_swp_soft_dirty(pteval))
swp_pte = pte_swp_mksoft_dirty(swp_pte);
if (pte_swp_uffd(pteval))
swp_pte = pte_swp_mkuffd(swp_pte);
}
set_pte_at(mm, address, pvmw.pte, swp_pte);
goto finish_unmap;
} else {
/*
* This is a locked file-backed folio,
@@ -2369,7 +2390,7 @@ 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);