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[195.135.220.15]) by mx.google.com with ESMTPS id l37si2592248edc.451.2019.03.27.10.33.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Mar 2019 10:33:34 -0700 (PDT) Received-SPF: pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of jack@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=jack@suse.cz X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 86E5EAFF2; Wed, 27 Mar 2019 17:33:33 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id C64591E1589; Wed, 27 Mar 2019 18:33:32 +0100 (CET) Date: Wed, 27 Mar 2019 18:33:32 +0100 From: Jan Kara To: Andrew Morton Cc: Jan Kara , Linux MM , "Aneesh Kumar K.V" , Chandan Rajendra , stable , Dan Williams Subject: Re: [PATCH] mm: Fix modifying of page protection by insert_pfn() Message-ID: <20190327173332.GA15475@quack2.suse.cz> References: <20190311084537.16029-1-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Mon 11-03-19 10:22:44, Dan Williams wrote: > On Mon, Mar 11, 2019 at 1:45 AM Jan Kara wrote: > > > > Aneesh has reported that PPC triggers the following warning when > > excercising DAX code: > > > > [c00000000007610c] set_pte_at+0x3c/0x190 > > LR [c000000000378628] insert_pfn+0x208/0x280 > > Call Trace: > > [c0000002125df980] [8000000000000104] 0x8000000000000104 (unreliable) > > [c0000002125df9c0] [c000000000378488] insert_pfn+0x68/0x280 > > [c0000002125dfa30] [c0000000004a5494] dax_iomap_pte_fault.isra.7+0x734/0xa40 > > [c0000002125dfb50] [c000000000627250] __xfs_filemap_fault+0x280/0x2d0 > > [c0000002125dfbb0] [c000000000373abc] do_wp_page+0x48c/0xa40 > > [c0000002125dfc00] [c000000000379170] __handle_mm_fault+0x8d0/0x1fd0 > > [c0000002125dfd00] [c00000000037a9b0] handle_mm_fault+0x140/0x250 > > [c0000002125dfd40] [c000000000074bb0] __do_page_fault+0x300/0xd60 > > [c0000002125dfe20] [c00000000000acf4] handle_page_fault+0x18 > > > > Now that is WARN_ON in set_pte_at which is > > > > VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); > > > > The problem is that on some architectures set_pte_at() cannot cope with > > a situation where there is already some (different) valid entry present. > > > > Use ptep_set_access_flags() instead to modify the pfn which is built to > > deal with modifying existing PTE. > > > > CC: stable@vger.kernel.org > > Fixes: b2770da64254 "mm: add vm_insert_mixed_mkwrite()" > > Reported-by: "Aneesh Kumar K.V" > > Signed-off-by: Jan Kara > > Acked-by: Dan Williams > > Andrew, can you pick this up? Andrew, ping? Honza -- Jan Kara SUSE Labs, CR