From efa3d814fad151ed5209539ecc1fc2880f7680b2 Mon Sep 17 00:00:00 2001 From: David Stevens Date: Tue, 4 Apr 2023 21:01:14 +0900 Subject: [PATCH] mm/khugepaged: drain lru after swapping in shmem Patch series "mm/khugepaged: fixes for khugepaged+shmem", v6. This series reworks collapse_file so that the intermediate state of the collapse does not leak out of collapse_file. Although this makes collapse_file a bit more complicated, it means that the rest of the kernel doesn't have to deal with the unusual state. This directly fixes races with both lseek and mincore. This series also fixes the fact that khugepaged completely breaks userfaultfd+shmem. The rework of collapse_file provides a convenient place to check for registered userfaultfds without making the shmem userfaultfd implementation care about khugepaged. Finally, this series adds a lru_add_drain after swapping in shmem pages, which makes the subsequent folio_isolate_lru significantly more likely to succeed. This patch (of 4): Call lru_add_drain after swapping in shmem pages so that isolate_lru_page is more likely to succeed. Link: https://lkml.kernel.org/r/20230404120117.2562166-1-stevensd@google.com Link: https://lkml.kernel.org/r/20230404120117.2562166-2-stevensd@google.com Signed-off-by: David Stevens Cc: David Hildenbrand Cc: Hugh Dickins Cc: Jiaqi Yan Cc: "Kirill A. Shutemov" Cc: Matthew Wilcox (Oracle) Cc: Peter Xu Cc: Yang Shi Signed-off-by: Andrew Morton --- mm/khugepaged.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index deea5c5..d92b614 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1967,6 +1967,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, result = SCAN_FAIL; goto xa_unlocked; } + /* drain pagevecs to help isolate_lru_page() */ + lru_add_drain(); page = folio_file_page(folio, index); } else if (trylock_page(page)) { get_page(page); -- 2.7.4