[RFC PATCH 5/7] pte_ref: add track_pte_{set, clear}() helper
From: Qi Zheng <hidden>
Date: 2022-08-25 10:12:39
Also in:
lkml
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
The track_pte_set() is used to track the setting of the PTE page table entry, and the track_pte_clear() is used to track the clearing of the PTE page table entry, we update the pte_refcount of the PTE page in these two functions. In this way, the usage of the PTE page table page can be tracked by its pte_refcount. Signed-off-by: Qi Zheng <redacted> --- include/linux/pte_ref.h | 13 +++++++++++++ mm/pte_ref.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+)
diff --git a/include/linux/pte_ref.h b/include/linux/pte_ref.h
index db14e03e1dff..ab49c7fac120 100644
--- a/include/linux/pte_ref.h
+++ b/include/linux/pte_ref.h@@ -12,12 +12,25 @@ void pte_ref_init(pgtable_t pte); +void track_pte_set(struct mm_struct *mm, unsigned long addr, pte_t *ptep, + pte_t pte); +void track_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep, + pte_t pte); #else /* !CONFIG_FREE_USER_PTE */ static inline void pte_ref_init(pgtable_t pte) { } +static inline void track_pte_set(struct mm_struct *mm, unsigned long addr, + pte_t *ptep, pte_t pte) +{ +} + +static inline void track_pte_clear(struct mm_struct *mm, unsigned long addr, + pte_t *ptep, pte_t pte) +{ +} #endif /* CONFIG_FREE_USER_PTE */ #endif /* _LINUX_PTE_REF_H */
diff --git a/mm/pte_ref.c b/mm/pte_ref.c
index 12b27646e88c..818821d068af 100644
--- a/mm/pte_ref.c
+++ b/mm/pte_ref.c@@ -69,4 +69,40 @@ void pte_ref_init(pgtable_t pte) pte->pte_refcount = 0; } +void track_pte_set(struct mm_struct *mm, unsigned long addr, pte_t *ptep, + pte_t pte) +{ + pgtable_t page; + + if (&init_mm == mm || pte_huge(pte)) + return; + + page = pte_to_page(ptep); + if (pte_none(*ptep) && !pte_none(pte)) { + pte_refcount_add(mm, page, PTE_MAPPED_OFFSET); + if (is_zero_pfn(pte_pfn(pte))) + pte_refcount_add(mm, page, PTE_ZERO_OFFSET); + } else if (is_zero_pfn(pte_pfn(*ptep)) && !is_zero_pfn(pte_pfn(pte))) { + pte_refcount_sub(mm, page, PTE_ZERO_OFFSET); + } +} +EXPORT_SYMBOL(track_pte_set); + +void track_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep, + pte_t pte) +{ + pgtable_t page; + + if (&init_mm == mm || pte_huge(pte)) + return; + + page = pte_to_page(ptep); + if (!pte_none(pte)) { + pte_refcount_sub(mm, page, PTE_MAPPED_OFFSET); + if (is_zero_pfn(pte_pfn(pte))) + pte_refcount_sub(mm, page, PTE_ZERO_OFFSET); + } +} +EXPORT_SYMBOL(track_pte_clear); + #endif /* CONFIG_FREE_USER_PTE */
--
2.20.1