From: Hugh Dickins hughd@google.com Subject: mm,thp: stop leaking unreleased file pages

When collapse_file() calls try_to_release_page(), it has already isolated the page: so if releasing buffers happens to fail (as it sometimes does), remember to putback_lru_page(): otherwise that page is left unreclaimable and unfreeable, and the file extent uncollapsible.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2005231837500.1766@eggly.anvils Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Song Liu songliubraving@fb.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Acked-by: Johannes Weiner hannes@cmpxchg.org Cc: Rik van Riel riel@surriel.com Cc: stable@vger.kernel.org [5.4+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/khugepaged.c | 1 + 1 file changed, 1 insertion(+)

--- a/mm/khugepaged.c~mmthp-stop-leaking-unreleased-file-pages +++ a/mm/khugepaged.c @@ -1692,6 +1692,7 @@ static void collapse_file(struct mm_stru if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) { result = SCAN_PAGE_HAS_PRIVATE; + putback_lru_page(page); goto out_unlock; }

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