linux-kernel - [PATCH v3 01/10] mm/memory: factor out zapping of present pte into zap_present

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Date: Wed, 14 Feb 2024 21:44:26 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Wilcox <willy@...radead.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Yin Fengwei <fengwei.yin@...el.com>,
	Michal Hocko <mhocko@...e.com>,
	Will Deacon <will@...nel.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
	Nick Piggin <npiggin@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Arnd Bergmann <arnd@...db.de>,
	linux-arch@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-s390@...r.kernel.org
Subject: [PATCH v3 01/10] mm/memory: factor out zapping of present pte into zap_present_pte()

Let's prepare for further changes by factoring out processing of present
PTEs.

Reviewed-by: Ryan Roberts <ryan.roberts@....com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory.c | 94 ++++++++++++++++++++++++++++++-----------------------
 1 file changed, 53 insertions(+), 41 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 7c3ca41a7610..5b0dc33133a6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1532,13 +1532,61 @@ zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
 	pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
 }
 
+static inline void zap_present_pte(struct mmu_gather *tlb,
+		struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
+		unsigned long addr, struct zap_details *details,
+		int *rss, bool *force_flush, bool *force_break)
+{
+	struct mm_struct *mm = tlb->mm;
+	struct folio *folio = NULL;
+	bool delay_rmap = false;
+	struct page *page;
+
+	page = vm_normal_page(vma, addr, ptent);
+	if (page)
+		folio = page_folio(page);
+
+	if (unlikely(!should_zap_folio(details, folio)))
+		return;
+	ptent = ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
+	arch_check_zapped_pte(vma, ptent);
+	tlb_remove_tlb_entry(tlb, pte, addr);
+	zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent);
+	if (unlikely(!page)) {
+		ksm_might_unmap_zero_page(mm, ptent);
+		return;
+	}
+
+	if (!folio_test_anon(folio)) {
+		if (pte_dirty(ptent)) {
+			folio_mark_dirty(folio);
+			if (tlb_delay_rmap(tlb)) {
+				delay_rmap = true;
+				*force_flush = true;
+			}
+		}
+		if (pte_young(ptent) && likely(vma_has_recency(vma)))
+			folio_mark_accessed(folio);
+	}
+	rss[mm_counter(folio)]--;
+	if (!delay_rmap) {
+		folio_remove_rmap_pte(folio, page, vma);
+		if (unlikely(page_mapcount(page) < 0))
+			print_bad_pte(vma, addr, ptent, page);
+	}
+	if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
+		*force_flush = true;
+		*force_break = true;
+	}
+}
+
 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma, pmd_t *pmd,
 				unsigned long addr, unsigned long end,
 				struct zap_details *details)
 {
+	bool force_flush = false, force_break = false;
 	struct mm_struct *mm = tlb->mm;
-	int force_flush = 0;
 	int rss[NR_MM_COUNTERS];
 	spinlock_t *ptl;
 	pte_t *start_pte;
@@ -1555,7 +1603,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	arch_enter_lazy_mmu_mode();
 	do {
 		pte_t ptent = ptep_get(pte);
-		struct folio *folio = NULL;
+		struct folio *folio;
 		struct page *page;
 
 		if (pte_none(ptent))
@@ -1565,45 +1613,9 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 			break;
 
 		if (pte_present(ptent)) {
-			unsigned int delay_rmap;
-
-			page = vm_normal_page(vma, addr, ptent);
-			if (page)
-				folio = page_folio(page);
-
-			if (unlikely(!should_zap_folio(details, folio)))
-				continue;
-			ptent = ptep_get_and_clear_full(mm, addr, pte,
-							tlb->fullmm);
-			arch_check_zapped_pte(vma, ptent);
-			tlb_remove_tlb_entry(tlb, pte, addr);
-			zap_install_uffd_wp_if_needed(vma, addr, pte, details,
-						      ptent);
-			if (unlikely(!page)) {
-				ksm_might_unmap_zero_page(mm, ptent);
-				continue;
-			}
-
-			delay_rmap = 0;
-			if (!folio_test_anon(folio)) {
-				if (pte_dirty(ptent)) {
-					folio_mark_dirty(folio);
-					if (tlb_delay_rmap(tlb)) {
-						delay_rmap = 1;
-						force_flush = 1;
-					}
-				}
-				if (pte_young(ptent) && likely(vma_has_recency(vma)))
-					folio_mark_accessed(folio);
-			}
-			rss[mm_counter(folio)]--;
-			if (!delay_rmap) {
-				folio_remove_rmap_pte(folio, page, vma);
-				if (unlikely(page_mapcount(page) < 0))
-					print_bad_pte(vma, addr, ptent, page);
-			}
-			if (unlikely(__tlb_remove_page(tlb, page, delay_rmap))) {
-				force_flush = 1;
+			zap_present_pte(tlb, vma, pte, ptent, addr, details,
+					rss, &force_flush, &force_break);
+			if (unlikely(force_break)) {
 				addr += PAGE_SIZE;
 				break;
 			}
-- 
2.43.0