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authorMiaohe Lin <linmiaohe@huawei.com>2021-09-03 00:59:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-03 19:58:17 +0300
commitd17be2d9ff6c689fd70d2d451153d613508a56ae (patch)
treee58a46b8c09e442cf387db7c7b5c5207c04cc77f
parent9647875be52b33fe22cb034ec3074896c581543f (diff)
downloadlinux-d17be2d9ff6c689fd70d2d451153d613508a56ae.tar.xz
mm/vmscan: remove the PageDirty check after MADV_FREE pages are page_ref_freezed
Patch series "Cleanups for vmscan", v2. This series contains cleanups to remove unneeded return value, misleading setting and so on. Also this remove the PageDirty check after MADV_FREE pages are page_ref_freezed. More details can be found in the respective changelogs. This patch (of 4): If the MADV_FREE pages are redirtied before they could be reclaimed, put the pages back to anonymous LRU list by setting SwapBacked flag and the pages will be reclaimed in normal swapout way. But as Yu Zhao pointed out, "The page has only one reference left, which is from the isolation. After the caller puts the page back on lru and drops the reference, the page will be freed anyway. It doesn't matter which lru it goes." So we don't bother checking PageDirty here. [Yu Zhao's comment is also quoted in the code.] Link: https://lkml.kernel.org/r/20210717065911.61497-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210717065911.61497-2-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: Yu Zhao <yuzhao@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alex Shi <alexs@kernel.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Shaohua Li <shli@fb.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/vmscan.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2255025f1891..044207d0bb66 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1732,11 +1732,14 @@ retry:
/* follow __remove_mapping for reference */
if (!page_ref_freeze(page, 1))
goto keep_locked;
- if (PageDirty(page)) {
- page_ref_unfreeze(page, 1);
- goto keep_locked;
- }
-
+ /*
+ * The page has only one reference left, which is
+ * from the isolation. After the caller puts the
+ * page back on lru and drops the reference, the
+ * page will be freed anyway. It doesn't matter
+ * which lru it goes. So we don't bother checking
+ * PageDirty here.
+ */
count_vm_event(PGLAZYFREED);
count_memcg_page_event(page, PGLAZYFREED);
} else if (!mapping || !__remove_mapping(mapping, page, true,