The patch titled
Subject: mm/khugepaged: drain lru after swapping in shmem
has been added to the -mm mm-unstable branch. Its filename is
mm-khugepaged-drain-lru-after-swapping-in-shmem.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-drain-lru-after-swapping-in-shmem.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Stevens <stevensd@xxxxxxxxxxxx>
Subject: mm/khugepaged: drain lru after swapping in shmem
Date: Tue, 4 Apr 2023 21:01:14 +0900
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@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20230404120117.2562166-2-stevensd@xxxxxxxxxx
Signed-off-by: David Stevens <stevensd@xxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jiaqi Yan <jiaqiyan@xxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/khugepaged.c~mm-khugepaged-drain-lru-after-swapping-in-shmem
+++ a/mm/khugepaged.c
@@ -1963,6 +1963,8 @@ static int collapse_file(struct mm_struc
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);
_
Patches currently in -mm which might be from stevensd@xxxxxxxxxxxx are
mm-khugepaged-drain-lru-after-swapping-in-shmem.patch
mm-khugepaged-refactor-collapse_file-control-flow.patch
mm-khugepaged-skip-shmem-with-userfaultfd.patch
mm-khugepaged-maintain-page-cache-uptodate-flag.patch
