From patchwork Fri Jul 17 07:20:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ira Weiny X-Patchwork-Id: 11669251 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6FE88618 for ; Fri, 17 Jul 2020 07:21:23 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5678B20775 for ; Fri, 17 Jul 2020 07:21:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5678B20775 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 55D8211EDD977; Fri, 17 Jul 2020 00:21:15 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=134.134.136.24; helo=mga09.intel.com; envelope-from=ira.weiny@intel.com; receiver= Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id D9E1F11EDD961 for ; Fri, 17 Jul 2020 00:21:09 -0700 (PDT) IronPort-SDR: rj1h5MzVcDfs8UqKc/Ot5qkSYHf6mfswSX2mIGAfgCPEYQi1ENR17DgZS7h0QJcN/O13QxF0nJ nGCKx2wm7uFQ== X-IronPort-AV: E=McAfee;i="6000,8403,9684"; a="150928919" X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="150928919" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2020 00:21:09 -0700 IronPort-SDR: YpmkIwj70j6oVnuZCPgm7Puk0Ze/LdT6Mtx+PLsWg4I1ZRpbL4Ii+GQfOj73MXeOUOarxnJ+rq LsrpPStzFBzg== X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="282708053" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2020 00:21:08 -0700 From: ira.weiny@intel.com To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Peter Zijlstra Subject: [PATCH RFC V2 14/17] dax: Stray write protection for dax_direct_access() Date: Fri, 17 Jul 2020 00:20:53 -0700 Message-Id: <20200717072056.73134-15-ira.weiny@intel.com> X-Mailer: git-send-email 2.28.0.rc0.12.gb6a658bd00c9 In-Reply-To: <20200717072056.73134-1-ira.weiny@intel.com> References: <20200717072056.73134-1-ira.weiny@intel.com> MIME-Version: 1.0 Message-ID-Hash: YSF6HELKLX5543O4NR5MHNVV72ZM3WOF X-Message-ID-Hash: YSF6HELKLX5543O4NR5MHNVV72ZM3WOF X-MailFrom: ira.weiny@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; suspicious-header CC: x86@kernel.org, Dave Hansen , Andrew Morton , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: From: Ira Weiny dax_direct_access() is a special case of accessing pmem via a page offset and without a struct page. Because the dax driver is well aware of the special protections it has mapped memory with, call dev_access_[en|dis]able() directly instead of the unnecessary overhead of trying to get a page to kmap. Like kmap though, leverage the existing dax_read[un]lock() functions because they are already required to surround the use of the memory returned from dax_direct_access(). Signed-off-by: Ira Weiny --- drivers/dax/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 021739768093..e8d0a28e6ed2 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -30,12 +30,14 @@ static DEFINE_SPINLOCK(dax_host_lock); int dax_read_lock(void) { + dev_access_enable(); return srcu_read_lock(&dax_srcu); } EXPORT_SYMBOL_GPL(dax_read_lock); void dax_read_unlock(int id) { + dev_access_disable(); srcu_read_unlock(&dax_srcu, id); } EXPORT_SYMBOL_GPL(dax_read_unlock);