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[195.135.220.15]) by mx.google.com with ESMTPS id t6si105184ejq.25.2019.04.26.01.36.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Apr 2019 01:36:55 -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 76901AF35; Fri, 26 Apr 2019 08:36:54 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id F01381E3618; Fri, 26 Apr 2019 10:36:53 +0200 (CEST) Date: Fri, 26 Apr 2019 10:36:53 +0200 From: Jan Kara To: Dan Williams Cc: Jan Kara , Matthew Wilcox , "Aneesh Kumar K.V" , Andrew Morton , linux-nvdimm , Linux MM , linuxppc-dev , stable , Chandan Rajendra Subject: Re: [PATCH v2] mm: Fix modifying of page protection by insert_pfn_pmd() Message-ID: <20190426083653.GB11637@quack2.suse.cz> References: <20190402115125.18803-1-aneesh.kumar@linux.ibm.com> <20190424173833.GE19031@bombadil.infradead.org> <20190425073149.GA21215@quack2.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 Thu 25-04-19 17:33:04, Dan Williams wrote: > On Thu, Apr 25, 2019 at 12:32 AM Jan Kara wrote: > > > > On Wed 24-04-19 11:13:48, Dan Williams wrote: > > > On Wed, Apr 24, 2019 at 10:38 AM Matthew Wilcox wrote: > > > > > > > > On Wed, Apr 24, 2019 at 10:13:15AM -0700, Dan Williams wrote: > > > > > I think unaligned addresses have always been passed to > > > > > vmf_insert_pfn_pmd(), but nothing cared until this patch. I *think* > > > > > the only change needed is the following, thoughts? > > > > > > > > > > diff --git a/fs/dax.c b/fs/dax.c > > > > > index ca0671d55aa6..82aee9a87efa 100644 > > > > > --- a/fs/dax.c > > > > > +++ b/fs/dax.c > > > > > @@ -1560,7 +1560,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct > > > > > vm_fault *vmf, pfn_t *pfnp, > > > > > } > > > > > > > > > > trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry); > > > > > - result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn, > > > > > + result = vmf_insert_pfn_pmd(vma, pmd_addr, vmf->pmd, pfn, > > > > > write); > > > > > > > > We also call vmf_insert_pfn_pmd() in dax_insert_pfn_mkwrite() -- does > > > > that need to change too? > > > > > > It wasn't clear to me that it was a problem. I think that one already > > > happens to be pmd-aligned. > > > > Why would it need to be? The address is taken from vmf->address and that's > > set up in __handle_mm_fault() like .address = address & PAGE_MASK. So I > > don't see anything forcing PMD alignment of the virtual address... > > True. So now I'm wondering if the masking should be done internal to > the routine. Given it's prefixed vmf_ it seems to imply the api is > prepared to take raw 'struct vm_fault' parameters. I think I'll go > that route unless someone sees a reason to require the caller to > handle this responsibility. Yeah, that sounds good to me. Thanks for fixing this. Honza -- Jan Kara SUSE Labs, CR