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Message-Id: <84a9fddde9993e4a5108f188193fd9c8ff1c5c31.1729157502.git.zhengqi.arch@bytedance.com>
Date: Thu, 17 Oct 2024 17:47:23 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: david@...hat.com,
hughd@...gle.com,
willy@...radead.org,
mgorman@...e.de,
muchun.song@...ux.dev,
vbabka@...nel.org,
akpm@...ux-foundation.org,
zokeefe@...gle.com,
rientjes@...gle.com,
jannh@...gle.com,
peterx@...hat.com
Cc: linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
x86@...nel.org,
Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v1 4/7] mm: zap_present_ptes: return whether the PTE page is unreclaimable
In the following two cases, the PTE page cannot be empty and cannot be
reclaimed:
1. an uffd-wp pte was re-installed
2. should_zap_folio() return false
Let's expose this information to the caller through is_pt_unreclaimable,
so that subsequent commits can use this information in zap_pte_range() to
detect whether the PTE page can be reclaimed.
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
mm/memory.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 534d9d52b5ebe..cc89ede8ce2ab 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1501,7 +1501,7 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
struct vm_area_struct *vma, struct folio *folio,
struct page *page, pte_t *pte, pte_t ptent, unsigned int nr,
unsigned long addr, struct zap_details *details, int *rss,
- bool *force_flush, bool *force_break)
+ bool *force_flush, bool *force_break, bool *is_pt_unreclaimable)
{
struct mm_struct *mm = tlb->mm;
bool delay_rmap = false;
@@ -1527,8 +1527,8 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
arch_check_zapped_pte(vma, ptent);
tlb_remove_tlb_entries(tlb, pte, nr, addr);
if (unlikely(userfaultfd_pte_wp(vma, ptent)))
- zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details,
- ptent);
+ *is_pt_unreclaimable =
+ zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent);
if (!delay_rmap) {
folio_remove_rmap_ptes(folio, page, nr, vma);
@@ -1552,7 +1552,7 @@ static inline int zap_present_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, bool *force_flush,
- bool *force_break)
+ bool *force_break, bool *is_pt_unreclaimable)
{
const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
struct mm_struct *mm = tlb->mm;
@@ -1567,15 +1567,18 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
arch_check_zapped_pte(vma, ptent);
tlb_remove_tlb_entry(tlb, pte, addr);
if (userfaultfd_pte_wp(vma, ptent))
- zap_install_uffd_wp_if_needed(vma, addr, pte, 1,
- details, ptent);
+ *is_pt_unreclaimable =
+ zap_install_uffd_wp_if_needed(vma, addr, pte, 1,
+ details, ptent);
ksm_might_unmap_zero_page(mm, ptent);
return 1;
}
folio = page_folio(page);
- if (unlikely(!should_zap_folio(details, folio)))
+ if (unlikely(!should_zap_folio(details, folio))) {
+ *is_pt_unreclaimable = true;
return 1;
+ }
/*
* Make sure that the common "small folio" case is as fast as possible
@@ -1587,11 +1590,12 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr,
addr, details, rss, force_flush,
- force_break);
+ force_break, is_pt_unreclaimable);
return nr;
}
zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, 1, addr,
- details, rss, force_flush, force_break);
+ details, rss, force_flush, force_break,
+ is_pt_unreclaimable);
return 1;
}
@@ -1622,6 +1626,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
pte_t ptent = ptep_get(pte);
struct folio *folio;
struct page *page;
+ bool is_pt_unreclaimable = false;
int max_nr;
nr = 1;
@@ -1635,7 +1640,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
max_nr = (end - addr) / PAGE_SIZE;
nr = zap_present_ptes(tlb, vma, pte, ptent, max_nr,
addr, details, rss, &force_flush,
- &force_break);
+ &force_break, &is_pt_unreclaimable);
if (unlikely(force_break)) {
addr += nr * PAGE_SIZE;
break;
--
2.20.1
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