From 9cc64c7fb9aee77d9bb471307eb2e0d5e8e6f986 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Mon, 27 Feb 2023 09:36:18 -0800 Subject: [PATCH] UPSTREAM: mm: conditionally write-lock VMA in free_pgtables Normally free_pgtables needs to lock affected VMAs except for the case when VMAs were isolated under VMA write-lock. munmap() does just that, isolating while holding appropriate locks and then downgrading mmap_lock and dropping per-VMA locks before freeing page tables. Add a parameter to free_pgtables for such scenario. Link: https://lkml.kernel.org/r/20230227173632.3292573-20-surenb@google.com Signed-off-by: Suren Baghdasaryan Signed-off-by: Andrew Morton (cherry picked from commit 98e51a2239d9d419d819cd61a2e720ebf19a8b0a) Bug: 161210518 Change-Id: I3c9177cce187526407754baf7641d3741ca7b0cb Signed-off-by: Suren Baghdasaryan --- mm/internal.h | 3 ++- mm/memory.c | 7 ++++++- mm/mmap.c | 5 +++-- 3 files changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index aa8496efa075..fe0925d7cbb5 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -87,7 +87,8 @@ void folio_activate(struct folio *folio); void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, struct vm_area_struct *start_vma, unsigned long floor, - unsigned long ceiling, unsigned long start_t); + unsigned long ceiling, unsigned long start_t, + bool mm_wr_locked); void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte); struct zap_details; diff --git a/mm/memory.c b/mm/memory.c index 6e3713b6bffb..12f47f2f44db 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -397,7 +397,8 @@ void free_pgd_range(struct mmu_gather *tlb, void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, struct vm_area_struct *vma, unsigned long floor, - unsigned long ceiling, unsigned long start_t) + unsigned long ceiling, unsigned long start_t, + bool mm_wr_locked) { MA_STATE(mas, mt, start_t, start_t); @@ -415,6 +416,8 @@ void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, * Hide vma from rmap and truncate_pagecache before freeing * pgtables */ + if (mm_wr_locked) + vma_start_write(vma); unlink_anon_vmas(vma); unlink_file_vma(vma); @@ -429,6 +432,8 @@ void free_pgtables(struct mmu_gather *tlb, struct maple_tree *mt, && !is_vm_hugetlb_page(next)) { vma = next; next = mas_find(&mas, ceiling - 1); + if (mm_wr_locked) + vma_start_write(vma); unlink_anon_vmas(vma); unlink_file_vma(vma); } diff --git a/mm/mmap.c b/mm/mmap.c index 3e5fd1c3dd76..192821327eb5 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2227,7 +2227,8 @@ static void unmap_region(struct mm_struct *mm, struct maple_tree *mt, update_hiwater_rss(mm); unmap_vmas(&tlb, mt, vma, start, end, start_t, end_t, mm_wr_locked); free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, - next ? next->vm_start : USER_PGTABLES_CEILING, start_t); + next ? next->vm_start : USER_PGTABLES_CEILING, start_t, + mm_wr_locked); tlb_finish_mmu(&tlb); } @@ -3163,7 +3164,7 @@ void exit_mmap(struct mm_struct *mm) mmap_write_lock(mm); mt_clear_in_rcu(&mm->mm_mt); free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS, - USER_PGTABLES_CEILING, vma->vm_end); + USER_PGTABLES_CEILING, vma->vm_end, true); tlb_finish_mmu(&tlb); /*