Commit 023e1a8d authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mm/rmap: fix new bug: premature return from page_mlock_one()

In the unlikely race case that page_mlock_one() finds VM_LOCKED has been
cleared by the time it got page table lock, page_vma_mapped_walk_done()
must be called before returning, either explicitly, or by a final call
to page_vma_mapped_walk() - otherwise the page table remains locked.

Fixes: cd62734c

 ("mm/rmap: split try_to_munlock from try_to_unmap")
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Reviewed-by: default avatarAlistair Popple <apopple@nvidia.com>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Reported-by: default avatarkernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/lkml/20210711151446.GB4070@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/lkml/f71f8523-cba7-3342-40a7-114abc5d1f51@google.com/


Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d9770fcc
......@@ -1990,14 +1990,13 @@ static bool page_mlock_one(struct page *page, struct vm_area_struct *vma,
* this function is never called when PageDoubleMap().
*/
mlock_vma_page(page);
/*
* No need to scan further once the page is marked
* as mlocked.
*/
page_vma_mapped_walk_done(&pvmw);
return false;
}
/*
* no need to continue scanning other vma's if the page has
* been locked.
*/
return false;
}
return true;
......
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