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t=1785404796; bh=ml3hDMc951hfxCEp24Za892tAl3WvI095gIkKqtQDCc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A2XQYDcYYUgRhC72cQtflDTyiASmK7g5hAdnpCdS2gwQ+jMCFf99+nYi5gno4T9yu Eq7iir+1vTyKVV+KCIhf9a3TsE5IMgltH/uG5miVrN9PCQlBRm4tgbwFIjMHE8UHCV zkwCBRYFDVP1YabtrETXkiAXccbSDHYsXoHkwfA4= From: Dev Jain To: akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, muchun.song@linux.dev, osalvador@suse.de Cc: Dev Jain , 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 v4 4/5] mm/rmap: refactor anon folio unmap in try_to_unmap_one Date: Thu, 30 Jul 2026 09:45:55 +0000 Message-ID: <20260730094559.418003-5-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260730094559.418003-1-dev.jain@arm.com> References: <20260730094559.418003-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 14FB81C0010 X-Stat-Signature: fnon8zdb65yefjqhgrzf6m9gzdoroibh X-HE-Tag: 1785404796-880143 X-HE-Meta: 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 0a33wacs m5QL2eDHXen5tYEKyWF88WHlgZqJ+s949ceNThLklhjftsav5s9/nLXsiiiXmnW0Ywi+0PrXwvEUb9P1O09poesXcgDcqDSj+8gVBuEaEk0+3ml4Gojg/zoI6xVXwQ2p+0+xU8BwX+FcQXERt7jtnJbl6NE2QJQjpdlARaG3K9SwRXJCjhM8RvK1p1nQeF4A9AXiqm5FmkjZ3w25x5XGefv7OOcYKSxRY34P07kAHEcJPAB4JG+rVJyB0FJFgYgzTso45m812kGKJBc0b3ywNL90kKT2wE28fLx7P9jJ+zBOcwEmwWeZLxoTpaGVDbomP+MI/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Acked-by: David Hildenbrand (Arm) Signed-off-by: Dev Jain --- mm/rmap.c | 115 ++++++++++++++++++++++++++++++++---------------------- 1 file changed, 68 insertions(+), 47 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index dd1309d72e37..15efde4d1fc9 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(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) { - 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(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); -- 2.43.0