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Message-Id: <25e70f171e17370ec65159a301ff4f852991e14c.1731566457.git.zhengqi.arch@bytedance.com>
Date: Thu, 14 Nov 2024 14:59:54 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: david@...hat.com,
jannh@...gle.com,
hughd@...gle.com,
willy@...radead.org,
muchun.song@...ux.dev,
vbabka@...nel.org,
akpm@...ux-foundation.org,
peterx@...hat.com
Cc: mgorman@...e.de,
catalin.marinas@....com,
will@...nel.org,
dave.hansen@...ux.intel.com,
luto@...nel.org,
peterz@...radead.org,
x86@...nel.org,
lorenzo.stoakes@...cle.com,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
zokeefe@...gle.com,
rientjes@...gle.com,
Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v3 3/9] mm: introduce zap_nonpresent_ptes()
Similar to zap_present_ptes(), let's introduce zap_nonpresent_ptes() to
handle non-present ptes, which can improve code readability.
No functional change.
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
Reviewed-by: Jann Horn <jannh@...gle.com>
Acked-by: David Hildenbrand <david@...hat.com>
---
mm/memory.c | 136 ++++++++++++++++++++++++++++------------------------
1 file changed, 73 insertions(+), 63 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 209885a4134f7..bd9ebe0f4471f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1587,6 +1587,76 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
return 1;
}
+static inline int zap_nonpresent_ptes(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
+ unsigned int max_nr, unsigned long addr,
+ struct zap_details *details, int *rss)
+{
+ swp_entry_t entry;
+ int nr = 1;
+
+ entry = pte_to_swp_entry(ptent);
+ if (is_device_private_entry(entry) ||
+ is_device_exclusive_entry(entry)) {
+ struct page *page = pfn_swap_entry_to_page(entry);
+ struct folio *folio = page_folio(page);
+
+ if (unlikely(!should_zap_folio(details, folio)))
+ return 1;
+ /*
+ * Both device private/exclusive mappings should only
+ * work with anonymous page so far, so we don't need to
+ * consider uffd-wp bit when zap. For more information,
+ * see zap_install_uffd_wp_if_needed().
+ */
+ WARN_ON_ONCE(!vma_is_anonymous(vma));
+ rss[mm_counter(folio)]--;
+ if (is_device_private_entry(entry))
+ folio_remove_rmap_pte(folio, page, vma);
+ folio_put(folio);
+ } else if (!non_swap_entry(entry)) {
+ /* Genuine swap entries, hence a private anon pages */
+ if (!should_zap_cows(details))
+ return 1;
+
+ nr = swap_pte_batch(pte, max_nr, ptent);
+ rss[MM_SWAPENTS] -= nr;
+ free_swap_and_cache_nr(entry, nr);
+ } else if (is_migration_entry(entry)) {
+ struct folio *folio = pfn_swap_entry_folio(entry);
+
+ if (!should_zap_folio(details, folio))
+ return 1;
+ rss[mm_counter(folio)]--;
+ } else if (pte_marker_entry_uffd_wp(entry)) {
+ /*
+ * For anon: always drop the marker; for file: only
+ * drop the marker if explicitly requested.
+ */
+ if (!vma_is_anonymous(vma) && !zap_drop_markers(details))
+ return 1;
+ } else if (is_guard_swp_entry(entry)) {
+ /*
+ * Ordinary zapping should not remove guard PTE
+ * markers. Only do so if we should remove PTE markers
+ * in general.
+ */
+ if (!zap_drop_markers(details))
+ return 1;
+ } else if (is_hwpoison_entry(entry) || is_poisoned_swp_entry(entry)) {
+ if (!should_zap_cows(details))
+ return 1;
+ } else {
+ /* We should have covered all the swap entry types */
+ pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
+ WARN_ON_ONCE(1);
+ }
+ clear_not_present_full_ptes(vma->vm_mm, addr, pte, nr, tlb->fullmm);
+ zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent);
+
+ return nr;
+}
+
static unsigned long zap_pte_range(struct mmu_gather *tlb,
struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end,
@@ -1598,7 +1668,6 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
spinlock_t *ptl;
pte_t *start_pte;
pte_t *pte;
- swp_entry_t entry;
int nr;
tlb_change_page_size(tlb, PAGE_SIZE);
@@ -1611,8 +1680,6 @@ 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;
- struct page *page;
int max_nr;
nr = 1;
@@ -1622,8 +1689,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (need_resched())
break;
+ max_nr = (end - addr) / PAGE_SIZE;
if (pte_present(ptent)) {
- max_nr = (end - addr) / PAGE_SIZE;
nr = zap_present_ptes(tlb, vma, pte, ptent, max_nr,
addr, details, rss, &force_flush,
&force_break);
@@ -1631,67 +1698,10 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
addr += nr * PAGE_SIZE;
break;
}
- continue;
- }
-
- entry = pte_to_swp_entry(ptent);
- if (is_device_private_entry(entry) ||
- is_device_exclusive_entry(entry)) {
- page = pfn_swap_entry_to_page(entry);
- folio = page_folio(page);
- if (unlikely(!should_zap_folio(details, folio)))
- continue;
- /*
- * Both device private/exclusive mappings should only
- * work with anonymous page so far, so we don't need to
- * consider uffd-wp bit when zap. For more information,
- * see zap_install_uffd_wp_if_needed().
- */
- WARN_ON_ONCE(!vma_is_anonymous(vma));
- rss[mm_counter(folio)]--;
- if (is_device_private_entry(entry))
- folio_remove_rmap_pte(folio, page, vma);
- folio_put(folio);
- } else if (!non_swap_entry(entry)) {
- max_nr = (end - addr) / PAGE_SIZE;
- nr = swap_pte_batch(pte, max_nr, ptent);
- /* Genuine swap entries, hence a private anon pages */
- if (!should_zap_cows(details))
- continue;
- rss[MM_SWAPENTS] -= nr;
- free_swap_and_cache_nr(entry, nr);
- } else if (is_migration_entry(entry)) {
- folio = pfn_swap_entry_folio(entry);
- if (!should_zap_folio(details, folio))
- continue;
- rss[mm_counter(folio)]--;
- } else if (pte_marker_entry_uffd_wp(entry)) {
- /*
- * For anon: always drop the marker; for file: only
- * drop the marker if explicitly requested.
- */
- if (!vma_is_anonymous(vma) &&
- !zap_drop_markers(details))
- continue;
- } else if (is_guard_swp_entry(entry)) {
- /*
- * Ordinary zapping should not remove guard PTE
- * markers. Only do so if we should remove PTE markers
- * in general.
- */
- if (!zap_drop_markers(details))
- continue;
- } else if (is_hwpoison_entry(entry) ||
- is_poisoned_swp_entry(entry)) {
- if (!should_zap_cows(details))
- continue;
} else {
- /* We should have covered all the swap entry types */
- pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
- WARN_ON_ONCE(1);
+ nr = zap_nonpresent_ptes(tlb, vma, pte, ptent, max_nr,
+ addr, details, rss);
}
- clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm);
- zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent);
} while (pte += nr, addr += PAGE_SIZE * nr, addr != end);
add_mm_rss_vec(mm, rss);
--
2.20.1
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