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 <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 83adf86..58704ca 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2167,7 +2167,8 @@ static void unmap_region(struct mm_struct *mm, struct maple_tree *mt,
update_hiwater_rss(mm);
unmap_vmas(&tlb, mt, vma, start, end, mm_wr_locked);
free_pgtables(&tlb, mt, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
- next ? next->vm_start : USER_PGTABLES_CEILING);
+ next ? next->vm_start : USER_PGTABLES_CEILING,
+ mm_wr_locked);
tlb_finish_mmu(&tlb);
}
@@ -3064,7 +3065,7 @@ void exit_mmap(struct mm_struct *mm)
set_bit(MMF_OOM_SKIP, &mm->flags);
mmap_write_lock(mm);
free_pgtables(&tlb, &mm->mm_mt, vma, FIRST_USER_ADDRESS,
- USER_PGTABLES_CEILING);
+ USER_PGTABLES_CEILING, true);
tlb_finish_mmu(&tlb);
/*
