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[209.85.220.65]) by mx.google.com with SMTPS id c127sor2747358oif.94.2019.04.25.17.33.15 for (Google Transport Security); Thu, 25 Apr 2019 17:33:16 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@intel-com.20150623.gappssmtp.com header.s=20150623 header.b=yxMG00XR; spf=pass (google.com: domain of dan.j.williams@intel.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=husfLeAUYRUpmyxx/IOBfWRF88c+2Bw6W/zLaIXEA5s=; b=yxMG00XRw8W8gPUsSvOidLXP7LF3BedxzpWzi1PTS4ri+eYU8v80sONYvSsjtJM2GW wFTOb6JqEVuH7DzSurkgHYEdEr3Q5zeBmpl84g+jca74K1GKrF7Xor93CJEIvFdldwmq En26Ux164dU7E+aT12PHHdcVIAIvrnsPs17DGqKrKxLJbHi8/eWFI24goDhTUHKiGjmm uJr1VWdSaFqAnpl3ZmXcYvoGsODlF/zfcC/FgybwVBvOqVGSOyFep/PP9tb1hDt/wcgX ZtyPCD8w+mPd1oiSGTqPEpbwpi4lxpVcmZZ7m6genkJjL6QG8Qx2OhHahDQqhdSOK6jn gwqA== X-Google-Smtp-Source: APXvYqw1+ZJvz+ZxUUyq0eqW43gC2WMrQ8d3BXIt3dl9j88+0wZGDtOHhjZNKsuCANGX8D3bycXuRTYIAelS2XRy3HE= X-Received: by 2002:aca:e64f:: with SMTP id d76mr5550827oih.105.1556238795714; Thu, 25 Apr 2019 17:33:15 -0700 (PDT) MIME-Version: 1.0 References: <20190402115125.18803-1-aneesh.kumar@linux.ibm.com> <20190424173833.GE19031@bombadil.infradead.org> <20190425073149.GA21215@quack2.suse.cz> In-Reply-To: <20190425073149.GA21215@quack2.suse.cz> From: Dan Williams Date: Thu, 25 Apr 2019 17:33:04 -0700 Message-ID: Subject: Re: [PATCH v2] mm: Fix modifying of page protection by insert_pfn_pmd() To: Jan Kara Cc: Matthew Wilcox , "Aneesh Kumar K.V" , Andrew Morton , linux-nvdimm , Linux MM , linuxppc-dev , stable , Chandan Rajendra Content-Type: text/plain; charset="UTF-8" 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, 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.