Since commit 0758cd830494 ("asm-generic/tlb: avoid potential double flush"),
TLB invalidation is elided in tlb_finish_mmu() if no entries were batched
via the tlb_remove_*() functions. Consequently, the page-table modifications
performed by clear_refs_write() in response to a write to
/proc/<pid>/clear_refs do not perform TLB invalidation. Although this is
fine when simply aging the ptes, in the case of clearing the "soft-dirty"
state we can end up with entries where pte_write() is false, yet a
writable mapping remains in the TLB.Fix this by calling tlb_remove_tlb_entry() for each entry being write-protected when cleating soft-dirty. Signed-off-by: Will Deacon <[email protected]> --- fs/proc/task_mmu.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index cd03ab9087b0..3308292ee5c5 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1032,11 +1032,12 @@ enum clear_refs_types { struct clear_refs_private { enum clear_refs_types type; + struct mmu_gather *tlb; }; #ifdef CONFIG_MEM_SOFT_DIRTY static inline void clear_soft_dirty(struct vm_area_struct *vma, - unsigned long addr, pte_t *pte) + unsigned long addr, pte_t *pte, struct mmu_gather *tlb) { /* * The soft-dirty tracker uses #PF-s to catch writes @@ -1053,6 +1054,7 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, ptent = pte_wrprotect(old_pte); ptent = pte_clear_soft_dirty(ptent); ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent); + tlb_remove_tlb_entry(tlb, pte, addr); } else if (is_swap_pte(ptent)) { ptent = pte_swp_clear_soft_dirty(ptent); set_pte_at(vma->vm_mm, addr, pte, ptent); @@ -1060,14 +1062,14 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, } #else static inline void clear_soft_dirty(struct vm_area_struct *vma, - unsigned long addr, pte_t *pte) + unsigned long addr, pte_t *pte, struct mmu_gather *tlb) { } #endif #if defined(CONFIG_MEM_SOFT_DIRTY) && defined(CONFIG_TRANSPARENT_HUGEPAGE) static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, - unsigned long addr, pmd_t *pmdp) + unsigned long addr, pmd_t *pmdp, struct mmu_gather *tlb) { pmd_t old, pmd = *pmdp; @@ -1081,6 +1083,7 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, pmd = pmd_wrprotect(pmd); pmd = pmd_clear_soft_dirty(pmd); + tlb_remove_pmd_tlb_entry(tlb, pmdp, addr); set_pmd_at(vma->vm_mm, addr, pmdp, pmd); } else if (is_migration_entry(pmd_to_swp_entry(pmd))) { @@ -1090,7 +1093,7 @@ static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, } #else static inline void clear_soft_dirty_pmd(struct vm_area_struct *vma, - unsigned long addr, pmd_t *pmdp) + unsigned long addr, pmd_t *pmdp, struct mmu_gather *tlb) { } #endif @@ -1107,7 +1110,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, ptl = pmd_trans_huge_lock(pmd, vma); if (ptl) { if (cp->type == CLEAR_REFS_SOFT_DIRTY) { - clear_soft_dirty_pmd(vma, addr, pmd); + clear_soft_dirty_pmd(vma, addr, pmd, cp->tlb); goto out; } @@ -1133,7 +1136,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, ptent = *pte; if (cp->type == CLEAR_REFS_SOFT_DIRTY) { - clear_soft_dirty(vma, addr, pte); + clear_soft_dirty(vma, addr, pte, cp->tlb); continue; } @@ -1212,7 +1215,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, if (mm) { struct mmu_notifier_range range; struct clear_refs_private cp = { - .type = type, + .type = type, + .tlb = &tlb, }; if (type == CLEAR_REFS_MM_HIWATER_RSS) { -- 2.29.2.454.gaff20da3a2-goog
