From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1C40C0044D for ; Mon, 16 Mar 2020 04:36:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8312320726 for ; Mon, 16 Mar 2020 04:36:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lY78JmHv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8312320726 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3678A6B0007; Mon, 16 Mar 2020 00:36:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 318386B0008; Mon, 16 Mar 2020 00:36:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 254BC6B000A; Mon, 16 Mar 2020 00:36:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0207.hostedemail.com [216.40.44.207]) by kanga.kvack.org (Postfix) with ESMTP id 0DC526B0007 for ; Mon, 16 Mar 2020 00:36:38 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E64E2180AD806 for ; Mon, 16 Mar 2020 04:36:37 +0000 (UTC) X-FDA: 76599964434.18.nose21_39dc6b41b5747 X-HE-Tag: nose21_39dc6b41b5747 X-Filterd-Recvd-Size: 5335 Received: from mail-pj1-f65.google.com (mail-pj1-f65.google.com [209.85.216.65]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Mon, 16 Mar 2020 04:36:37 +0000 (UTC) Received: by mail-pj1-f65.google.com with SMTP id dw20so3577092pjb.0 for ; Sun, 15 Mar 2020 21:36:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=fsI1XEPfE/anfkLEVKGW8+YR1eBwmOuLro1LuQ5D+DY=; b=lY78JmHvz9cs070waBtw18dVt/JAt1JesCwcF86+QyxzR24E+YBrxUXkR/AK2qLJvP Gly4wGAIMmEX/DPr0ss4mghlm9pEQY8aQ7XLR3FpBNBXTvMk9LEh82wdwpP60IezSkiQ ozO2Z3LJzup6BX1xKCI70IFlsuQvq9xPgppJT6iSjQ0nAiFiVSwYzYTJBw/9gZvxLu/a C4HKd3s/riXihuFhxygEj2EIvgheh8XnlIVEDpDp3AbucwuOkJAJGfrPft0hUdqcHWHc nT07koP4VVT3QRn85cIOLvVQiAyUkrF4rb2LNMeTXeksIQSA4N8AqXkbD0wRXseQWYXn kddw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=fsI1XEPfE/anfkLEVKGW8+YR1eBwmOuLro1LuQ5D+DY=; b=b48Co5KTRFDUKW3j9oIPvc13hmc8aldUNi6LzfzeQNbtNcfssE15NcF7X2YQF9GIM7 gd4xi3hCRFLCv6erqN2cxNxNixTA5qWxdqidwHCmSRP6nON/MUu92+Qa4g+nxo5tfHqz n3N91IeAvuqyFUpsMEM2rwp5m5yjJnn6II/mPgqKliOmI7wLA+ZnnP0/Q0d4byNszWV3 QgDFZwuTf+qqzJXLe06AlW6PEK15DNxy5Fw7WLhiT5Omj/oZPPzKsxwAa0jkW8Nbccm6 t8mOyBslTqH6SeHyuUvZUqam3Or765hcGDX2g3b3tMPS4YvDFY5s5yKrZdDtwIbOVMXc 4KhQ== X-Gm-Message-State: ANhLgQ0ebitShT2JVUxJiB5bo8fiW0pl5ttq7vsBWHM2quILK2ze6bLt MDk58irIgKQEBqhZS01UnKc0FKM= X-Google-Smtp-Source: ADFU+vulhz01sa+o+LgPj7GJ2sEvA2tjhDbL8mGwGMZalaeaW7dwYM8zUJLj3g0jTqZYwlIjEohU0Q== X-Received: by 2002:a17:90a:2:: with SMTP id 2mr23785492pja.16.1584333396201; Sun, 15 Mar 2020 21:36:36 -0700 (PDT) Received: from mylaptop.redhat.com ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id d6sm18544296pjz.39.2020.03.15.21.36.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 15 Mar 2020 21:36:35 -0700 (PDT) From: Pingfan Liu To: linux-mm@kvack.org Cc: Pingfan Liu , Ira Weiny , Andrew Morton , Mike Rapoport , Dan Williams , Matthew Wilcox , John Hubbard , "Aneesh Kumar K.V" , Christoph Hellwig , Shuah Khan , Jason Gunthorpe , linux-kernel@vger.kernel.org Subject: [PATCHv6 2/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path Date: Mon, 16 Mar 2020 12:34:03 +0800 Message-Id: <1584333244-10480-3-git-send-email-kernelfans@gmail.com> X-Mailer: git-send-email 2.7.5 In-Reply-To: <1584333244-10480-1-git-send-email-kernelfans@gmail.com> References: <1584333244-10480-1-git-send-email-kernelfans@gmail.com> 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: FOLL_LONGTERM is a special case of FOLL_PIN. It suggests a pin which is going to be given to hardware and can't move. It would truncate CMA permanently and should be excluded. In gup slow path, slow path, where __gup_longterm_locked->check_and_migrate_cma_pages() handles FOLL_LONGTERM, but in fast path, there lacks such a check, which means a possible leak of CMA page to longterm pinned. Place a check in try_grab_compound_head() in the fast path to fix the leak, and if FOLL_LONGTERM happens on CMA, it will fall back to slow path to migrate the page. Some note about the check: Huge page's subpages have the same migrate type due to either allocation from a free_list[] or alloc_contig_range() with param MIGRATE_MOVABLE. So it is enough to check on a single subpage by is_migrate_cma_page(subpage) Signed-off-by: Pingfan Liu Cc: Ira Weiny Cc: Andrew Morton Cc: Mike Rapoport Cc: Dan Williams Cc: Matthew Wilcox Cc: John Hubbard Cc: "Aneesh Kumar K.V" Cc: Christoph Hellwig Cc: Shuah Khan Cc: Jason Gunthorpe To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/gup.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index 9df77b1..78132cf 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -89,6 +89,15 @@ static __maybe_unused struct page *try_grab_compound_head(struct page *page, int orig_refs = refs; /* + * Huge page's subpages have the same migrate type due to either + * allocation from a free_list[] or alloc_contig_range() with + * param MIGRATE_MOVABLE. So it is enough to check on a subpage. + */ + if (unlikely(flags & FOLL_LONGTERM) && + is_migrate_cma_page(page)) + return NULL; + + /* * When pinning a compound page of order > 1 (which is what * hpage_pincount_available() checks for), use an exact count to * track it, via hpage_pincount_add/_sub(). -- 2.7.5