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Jann Horn
2ba99c5e08
Since commit70cbc3cc78("mm: gup: fix the fast GUP race against THP collapse"), the lockless_pages_from_mm() fastpath rechecks the pmd_t to ensure that the page table was not removed by khugepaged in between. However, lockless_pages_from_mm() still requires that the page table is not concurrently freed. Fix it by sending IPIs (if the architecture uses semi-RCU-style page table freeing) before freeing/reusing page tables. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Fixes:ba76149f47("thp: khugepaged") Signed-off-by: Jann Horn <[email protected]> Reviewed-by: Yang Shi <[email protected]> Acked-by: David Hildenbrand <[email protected]> Cc: John Hubbard <[email protected]> Cc: Peter Xu <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]>