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Shutemov" X-Google-Original-From: "Kirill A. Shutemov" Received: by box.localdomain (Postfix, from userid 1000) id 699D3100D28; Fri, 27 Mar 2020 20:06:07 +0300 (+03) To: akpm@linux-foundation.org, Andrea Arcangeli Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH 3/7] khugepaged: Drain LRU add pagevec to get rid of extra pins Date: Fri, 27 Mar 2020 20:05:57 +0300 Message-Id: <20200327170601.18563-4-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200327170601.18563-1-kirill.shutemov@linux.intel.com> References: <20200327170601.18563-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: __collapse_huge_page_isolate() may fail due to extra pin in the LRU add pagevec. It's petty common for swapin case: we swap in pages just to fail due to the extra pin. Signed-off-by: Kirill A. Shutemov --- mm/khugepaged.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 14d7afc90786..39e0994abeb8 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -585,11 +585,19 @@ static int __collapse_huge_page_isolate(struct vm_a= rea_struct *vma, * The page must only be referenced by the scanned process * and page swap cache. */ + if (page_count(page) !=3D 1 + PageSwapCache(page)) { + /* + * Drain pagevec and retry just in case we can get rid + * of the extra pin, like in swapin case. + */ + lru_add_drain(); + } if (page_count(page) !=3D 1 + PageSwapCache(page)) { unlock_page(page); result =3D SCAN_PAGE_COUNT; goto out; } + if (pte_write(pteval)) { writable =3D true; } else { --=20 2.26.0