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mm/madvise: fix potential pte_unmap_unlock pte error

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We can't assume pte_offset_map_lock will return same orig_pte value. So
it's necessary to reacquire the orig_pte or pte_unmap_unlock will unmap
the stale pte.

Link: https://lkml.kernel.org/r/20220416081416.23304-1-linmiaohe@huawei.com
Fixes: 9c276cc65a ("mm: introduce MADV_COLD")
Fixes: 854e9ed09d ("mm: support madvise(MADV_FREE)")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2022-04-28 23:16:09 -07:00 committed by akpm
parent 7d6e2d9638
commit f3b9e8cc8b
1 changed files with 4 additions and 4 deletions
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8
mm/madvise.c
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@ -432,12 +432,12 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
if (split_huge_page(page)) {
unlock_page(page);
put_page(page);
pte_offset_map_lock(mm, pmd, addr, &ptl);
orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
break;
}
unlock_page(page);
put_page(page);
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
pte--;
addr -= PAGE_SIZE;
continue;
@ -648,12 +648,12 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
if (split_huge_page(page)) {
unlock_page(page);
put_page(page);
pte_offset_map_lock(mm, pmd, addr, &ptl);
orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
goto out;
}
unlock_page(page);
put_page(page);
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
pte--;
addr -= PAGE_SIZE;
continue;