The patch titled
Subject: riscv: pgtable: move pagetable_dtor() to __tlb_remove_table()
has been added to the -mm mm-unstable branch. Its filename is
riscv-pgtable-move-pagetable_dtor-to-__tlb_remove_table.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/riscv-pgtable-move-pagetable_dtor-to-__tlb_remove_table.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: riscv: pgtable: move pagetable_dtor() to __tlb_remove_table()
Date: Mon, 23 Dec 2024 17:40:56 +0800
Move pagetable_dtor() to __tlb_remove_table(), so that ptlock and page
table pages can be freed together (regardless of whether RCU is used).
This prevents the use-after-free problem where the ptlock is freed
immediately but the page table pages is freed later via RCU.
Page tables shouldn't have swap cache, so use pagetable_free() instead of
free_page_and_swap_cache() to free page table pages.
By the way, move the comment above __tlb_remove_table() to
riscv_tlb_remove_ptdesc(), it will be more appropriate.
Link: https://lkml.kernel.org/r/0e8f0b3835c15e99145e0006ac1020ae45a2b166.1734945104.git.zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V (Arm) <aneesh.kumar@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/riscv/include/asm/pgalloc.h | 38 ++++++++++++-----------------
arch/riscv/include/asm/tlb.h | 14 +++-------
2 files changed, 21 insertions(+), 31 deletions(-)
--- a/arch/riscv/include/asm/pgalloc.h~riscv-pgtable-move-pagetable_dtor-to-__tlb_remove_table
+++ a/arch/riscv/include/asm/pgalloc.h
@@ -15,12 +15,22 @@
#define __HAVE_ARCH_PUD_FREE
#include <asm-generic/pgalloc.h>
+/*
+ * While riscv platforms with riscv_ipi_for_rfence as true require an IPI to
+ * perform TLB shootdown, some platforms with riscv_ipi_for_rfence as false use
+ * SBI to perform TLB shootdown. To keep software pagetable walkers safe in this
+ * case we switch to RCU based table free (MMU_GATHER_RCU_TABLE_FREE). See the
+ * comment below 'ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE' in include/asm-generic/tlb.h
+ * for more details.
+ */
static inline void riscv_tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
{
- if (riscv_use_sbi_for_rfence())
+ if (riscv_use_sbi_for_rfence()) {
tlb_remove_ptdesc(tlb, pt);
- else
+ } else {
+ pagetable_dtor(pt);
tlb_remove_page_ptdesc(tlb, pt);
+ }
}
static inline void pmd_populate_kernel(struct mm_struct *mm,
@@ -97,23 +107,15 @@ static inline void pud_free(struct mm_st
static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
unsigned long addr)
{
- if (pgtable_l4_enabled) {
- struct ptdesc *ptdesc = virt_to_ptdesc(pud);
-
- pagetable_dtor(ptdesc);
- riscv_tlb_remove_ptdesc(tlb, ptdesc);
- }
+ if (pgtable_l4_enabled)
+ riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(pud));
}
static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
unsigned long addr)
{
- if (pgtable_l5_enabled) {
- struct ptdesc *ptdesc = virt_to_ptdesc(p4d);
-
- pagetable_dtor(ptdesc);
+ if (pgtable_l5_enabled)
riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(p4d));
- }
}
#endif /* __PAGETABLE_PMD_FOLDED */
@@ -142,10 +144,7 @@ static inline pgd_t *pgd_alloc(struct mm
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
unsigned long addr)
{
- struct ptdesc *ptdesc = virt_to_ptdesc(pmd);
-
- pagetable_dtor(ptdesc);
- riscv_tlb_remove_ptdesc(tlb, ptdesc);
+ riscv_tlb_remove_ptdesc(tlb, virt_to_ptdesc(pmd));
}
#endif /* __PAGETABLE_PMD_FOLDED */
@@ -153,10 +152,7 @@ static inline void __pmd_free_tlb(struct
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
unsigned long addr)
{
- struct ptdesc *ptdesc = page_ptdesc(pte);
-
- pagetable_dtor(ptdesc);
- riscv_tlb_remove_ptdesc(tlb, ptdesc);
+ riscv_tlb_remove_ptdesc(tlb, page_ptdesc(pte));
}
#endif /* CONFIG_MMU */
--- a/arch/riscv/include/asm/tlb.h~riscv-pgtable-move-pagetable_dtor-to-__tlb_remove_table
+++ a/arch/riscv/include/asm/tlb.h
@@ -11,19 +11,13 @@ struct mmu_gather;
static void tlb_flush(struct mmu_gather *tlb);
#ifdef CONFIG_MMU
-#include <linux/swap.h>
-/*
- * While riscv platforms with riscv_ipi_for_rfence as true require an IPI to
- * perform TLB shootdown, some platforms with riscv_ipi_for_rfence as false use
- * SBI to perform TLB shootdown. To keep software pagetable walkers safe in this
- * case we switch to RCU based table free (MMU_GATHER_RCU_TABLE_FREE). See the
- * comment below 'ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE' in include/asm-generic/tlb.h
- * for more details.
- */
static inline void __tlb_remove_table(void *table)
{
- free_page_and_swap_cache(table);
+ struct ptdesc *ptdesc = (struct ptdesc *)table;
+
+ pagetable_dtor(ptdesc);
+ pagetable_free(ptdesc);
}
#endif /* CONFIG_MMU */
_
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-userfaultfd-recheck-dst_pmd-entry-in-move_pages_pte-fix.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
mm-pgtable-reclaim-empty-pte-page-in-madvisemadv_dontneed-fix.patch
x86-mm-free-page-table-pages-by-rcu-instead-of-semi-rcu.patch
mm-pgtable-make-ptlock-be-freed-by-rcu.patch
x86-select-arch_supports_pt_reclaim-if-x86_64.patch
revert-mm-pgtable-make-ptlock-be-freed-by-rcu.patch
mm-pgtable-add-statistics-for-p4d-level-page-table.patch
arm64-pgtable-use-mmu-gather-to-free-p4d-level-page-table.patch
s390-pgtable-add-statistics-for-pud-and-p4d-level-page-table.patch
mm-pgtable-introduce-pagetable_dtor.patch
arm-pgtable-move-pagetable_dtor-to-__tlb_remove_table.patch
arm64-pgtable-move-pagetable_dtor-to-__tlb_remove_table.patch
riscv-pgtable-move-pagetable_dtor-to-__tlb_remove_table.patch
x86-pgtable-move-pagetable_dtor-to-__tlb_remove_table.patch
s390-pgtable-also-move-pagetable_dtor-of-pxd-to-__tlb_remove_table.patch
mm-pgtable-introduce-generic-__tlb_remove_table.patch
mm-pgtable-move-__tlb_remove_table_one-in-x86-to-generic-file.patch
mm-pgtable-remove-tlb_remove_page_ptdesc.patch
mm-pgtable-remove-tlb_remove_ptdesc.patch
mm-pgtable-introduce-generic-pagetable_dtor_free.patch
