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authorMarek Szyprowski <m.szyprowski@samsung.com>2021-10-18 15:16:19 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-10-27 09:59:53 +0200
commitc4813d3085171dc3b2bfbd0b7e492fcc0a289eab (patch)
treef0d75e09703cb43c7a6dab2646dc6ae9110ee143
parenta7fbb56e6c941d9f59437b96412a348e66388d3e (diff)
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mm/thp: decrease nr_thps in file's mapping on THP split
[ Upstream commit 1ca7554d05ac038c98271f8968ed821266ecaa9c ] Decrease nr_thps counter in file's mapping to ensure that the page cache won't be dropped excessively on file write access if page has been already split. I've tried a test scenario running a big binary, kernel remaps it with THPs, then force a THP split with /sys/kernel/debug/split_huge_pages. During any further open of that binary with O_RDWR or O_WRITEONLY kernel drops page cache for it, because of non-zero thps counter. Link: https://lkml.kernel.org/r/20211012120237.2600-1-m.szyprowski@samsung.com Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Fixes: 09d91cda0e82 ("mm,thp: avoid writes to file with THP in pagecache") Fixes: 06d3eff62d9d ("mm/thp: fix node page state in split_huge_page_to_list()") Acked-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: <sfoon.kim@samsung.com> Cc: Song Liu <songliubraving@fb.com> Cc: Rik van Riel <riel@surriel.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--mm/huge_memory.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index afff3ac87067..163c2da2a654 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2724,12 +2724,14 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
if (mapping) {
int nr = thp_nr_pages(head);
- if (PageSwapBacked(head))
+ if (PageSwapBacked(head)) {
__mod_lruvec_page_state(head, NR_SHMEM_THPS,
-nr);
- else
+ } else {
__mod_lruvec_page_state(head, NR_FILE_THPS,
-nr);
+ filemap_nr_thps_dec(mapping);
+ }
}
__split_huge_page(page, list, end);