On 4/3/20 4:29 AM, Kirill A. Shutemov wrote:
__collapse_huge_page_isolate() may fail due to extra pin in the LRU add pagevec. It's petty common for swapin case: we swap in pages just to fail due to the extra pin. Drain LRU add pagevec on sucessfull swapin. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> --- mm/khugepaged.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index fdc10ffde1ca..57ff287caf6b 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -940,6 +940,11 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, } vmf.pte--; pte_unmap(vmf.pte); + + /* Drain LRU add pagevec to remove extra pin on the swapped in pages */ + if (swapped_in) + lru_add_drain();
There is already lru_add_drain() called in swap readahead path, please see swap_vma_readahead() and swap_cluster_readahead().
The extra call to draining lru seems unnecessary.
+ trace_mm_collapse_huge_page_swapin(mm, swapped_in, referenced, 1); return true; }
