The patch titled
Subject: mm: introduce zap_nonpresent_ptes()
has been added to the -mm mm-unstable branch. Its filename is
mm-introduce-zap_nonpresent_ptes.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-zap_nonpresent_ptes.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Subject: mm: introduce zap_nonpresent_ptes()
Date: Wed, 4 Dec 2024 19:09:43 +0800
Similar to zap_present_ptes(), let's introduce zap_nonpresent_ptes() to
handle non-present ptes, which can improve code readability.
No functional change.
Link: https://lkml.kernel.org/r/009ca882036d9c7a9f815489cfeafe0bdb79d62d.1733305182.git.zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Reviewed-by: Jann Horn <jannh@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Zach O'Keefe <zokeefe@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 136 ++++++++++++++++++++++++++------------------------
1 file changed, 73 insertions(+), 63 deletions(-)
--- a/mm/memory.c~mm-introduce-zap_nonpresent_ptes
+++ a/mm/memory.c
@@ -1587,6 +1587,76 @@ static inline int zap_present_ptes(struc
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(struc
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(struc
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(struc
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(struc
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);
_
Patches currently in -mm which might be from zhengqi.arch@xxxxxxxxxxxxx are
mm-pgtable-make-ptep_clear-non-atomic.patch
mm-khugepaged-recheck-pmd-state-in-retract_page_tables.patch
mm-userfaultfd-recheck-dst_pmd-entry-in-move_pages_pte.patch
mm-introduce-zap_nonpresent_ptes.patch
mm-introduce-do_zap_pte_range.patch
mm-skip-over-all-consecutive-none-ptes-in-do_zap_pte_range.patch
mm-zap_install_uffd_wp_if_needed-return-whether-uffd-wp-pte-has-been-re-installed.patch
mm-do_zap_pte_range-return-any_skipped-information-to-the-caller.patch
mm-make-zap_pte_range-handle-full-within-pmd-range.patch
mm-pgtable-reclaim-empty-pte-page-in-madvisemadv_dontneed.patch
x86-mm-free-page-table-pages-by-rcu-instead-of-semi-rcu.patch
x86-select-arch_supports_pt_reclaim-if-x86_64.patch
