mm: fix the racy mm->locked_vm change in
"mm->locked_vm += grow" and vm_stat_account() in acct_stack_growth() are not safe; multiple threads using the same ->mm can do this at the same time trying to expans different vma's under down_read(mmap_sem). This means that one of the "locked_vm += grow" changes can be lost and we can miss munlock_vma_pages_all() later. Move this code into the caller(s) under mm->page_table_lock. All other updates to ->locked_vm hold mmap_sem for writing. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Родитель
9fd745d450
Коммит
87e8827b37
12
mm/mmap.c
12
mm/mmap.c
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@ -2138,10 +2138,6 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
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if (security_vm_enough_memory_mm(mm, grow))
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return -ENOMEM;
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/* Ok, everything looks good - let it rip */
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if (vma->vm_flags & VM_LOCKED)
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mm->locked_vm += grow;
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vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
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return 0;
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}
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@ -2202,6 +2198,10 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
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* against concurrent vma expansions.
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*/
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spin_lock(&vma->vm_mm->page_table_lock);
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if (vma->vm_flags & VM_LOCKED)
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vma->vm_mm->locked_vm += grow;
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vm_stat_account(vma->vm_mm, vma->vm_flags,
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vma->vm_file, grow);
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anon_vma_interval_tree_pre_update_vma(vma);
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vma->vm_end = address;
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anon_vma_interval_tree_post_update_vma(vma);
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@ -2273,6 +2273,10 @@ int expand_downwards(struct vm_area_struct *vma,
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* against concurrent vma expansions.
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*/
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spin_lock(&vma->vm_mm->page_table_lock);
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if (vma->vm_flags & VM_LOCKED)
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vma->vm_mm->locked_vm += grow;
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vm_stat_account(vma->vm_mm, vma->vm_flags,
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vma->vm_file, grow);
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anon_vma_interval_tree_pre_update_vma(vma);
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vma->vm_start = address;
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vma->vm_pgoff -= grow;
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