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[198.145.29.99]) by mx.google.com with ESMTPS id z190si22185024pgd.303.2019.07.16.15.00.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Jul 2019 15:00:49 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=XSWiZuBk; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 459DC217D9; Tue, 16 Jul 2019 22:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563314448; bh=MZiI+dn9mTuyzIwRcV9Xmn9Ls3mvI60j/scPusuitoY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XSWiZuBkMQon8Lef5PmzojoSZZ9fRe2jegeNSZnEenhkD8cdTCQlE6EJpSJoBqgjy wUCAz9PwWcsuoV7ZdQqEhoN9Mox91kVFBCk9L9u6wGxpu+qMlGIrkxCGHu/x3UMAnl J8ebYbD6PKGFHh6l70c9iZEJlyazzO5W9LuTVRLw= Date: Tue, 16 Jul 2019 15:00:47 -0700 From: Andrew Morton To: Nadav Amit Cc: Dan Williams , Linux Kernel Mailing List , Linux MM , Borislav Petkov , Toshi Kani , Peter Zijlstra , Dave Hansen , Bjorn Helgaas , Ingo Molnar Subject: Re: [PATCH 0/3] resource: find_next_iomem_res() improvements Message-Id: <20190716150047.3c13945decc052c077e9ee1e@linux-foundation.org> In-Reply-To: <19C3DCA0-823E-46CB-A758-D5F82C5FA3C8@vmware.com> References: <20190613045903.4922-1-namit@vmware.com> <9387A285-B768-4B58-B91B-61B70D964E6E@vmware.com> <19C3DCA0-823E-46CB-A758-D5F82C5FA3C8@vmware.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Tue, 18 Jun 2019 21:56:43 +0000 Nadav Amit wrote: > > ...and is constant for the life of the device and all subsequent mappings. > > > >> Perhaps you want to cache the cachability-mode in vma->vm_page_prot (which I > >> see being done in quite a few cases), but I don’t know the code well enough > >> to be certain that every vma should have a single protection and that it > >> should not change afterwards. > > > > No, I'm thinking this would naturally fit as a property hanging off a > > 'struct dax_device', and then create a version of vmf_insert_mixed() > > and vmf_insert_pfn_pmd() that bypass track_pfn_insert() to insert that > > saved value. > > Thanks for the detailed explanation. I’ll give it a try (the moment I find > some free time). I still think that patch 2/3 is beneficial, but based on > your feedback, patch 3/3 should be dropped. It has been a while. What should we do with resource-fix-locking-in-find_next_iomem_res.patch resource-avoid-unnecessary-lookups-in-find_next_iomem_res.patch ?