From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0CBC1A9F97 for ; Fri, 2 Oct 2026 12:19:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790943548; cv=none; b=U6TNYWS8TRyCBXCFz4qzaJJ8oFw7cx9t3De5DjcmQDgcYyIIHBs6bcgatKtIhgKxMzTc5N3PQ3Bwd8iH7TPx3X8IGtYLViDN1zz6vgadzFkL/U5TYA7OEghXKQSzpDXPEqsG9Q31IpV53TEP9XmiznqwrwxY4BHwXddWr+glV0k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790943548; c=relaxed/simple; bh=Ad1Q1HbqcHCkaA7ORmy/Z4jWAPYEJSSTqoHgy897F4A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CUMh+KI12WTP1q0vvDHOs9a+Oa3NdJrMDjHa/NH20OZt7gadRkNAt9YTzIwsnjfyKpETshxpM5oKbDyrdBJIZfyi/5qsIv4Jx5u42Bl5MzO+8zA9K0H3R6MRHK5S9+94PUem69aYTur2nL46Zw/rkouL71e+FNnV66R3Ze7pWOc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cpOf350q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cpOf350q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 891D81F000FF; Fri, 2 Oct 2026 12:19:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790943547; bh=RWu9e92IrDGxSiXWBdyugaL6uysiiOtkTkm6Sf0sRHs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=cpOf350q1+IqKbjq3pAaHeVGWsdV2XTQIVpzRCzS5t+71aK85iZ/VSu+PQs0YIAtq QTzbVeLMZ7h7PO+YudkRqENz+QtL8biLtdQ5ZoY94rKhWfrf/38jl+/iz7QtIMc4hK pMPLdl9EY4aYBw/uNdoe7yF2uZaLuDYv6fOBug3bRtzB7Aek5ikndYSLeSSXuq37Pp ZY3jDxwC8bCuyK1sDrwnLwYI4079YamJ3eVvgFf16V5EELUXKPFBfFUSGjybGKU3Z0 2bVoTh2vNwl6q5KhVzSr0SC+P8I3XSyrK7JpWcJk7l56gtBbWlgA1kV6Oei0e9xRLz 97qvr0v/yuLgA== Message-ID: <494d436c-e3b3-4b65-8a6c-1059d9f468d4@kernel.org> Date: Fri, 2 Oct 2026 14:19:00 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: don't ioremap COWed anon pages in generic_access_phys() To: "Lorenzo Stoakes (ARM)" Cc: Nguyen Ngoc Thang , akpm@linux-foundation.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, peterx@redhat.com, dave.hansen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+49b1021becba70c1f3f6@syzkaller.appspotmail.com References: <699ae98c.050a0220.340abe.0d31.GAE@google.com> <20261001152524.171115-1-ngocthang2710.1999@gmail.com> <32fe40e2-854a-47ec-9d95-93e23f9a7af4@kernel.org> <9d43234f-93cb-4c86-a2a6-a3cdebf48f3b@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/2/26 12:09, Lorenzo Stoakes (ARM) wrote: > On Fri, Oct 02, 2026 at 12:04:27PM +0200, David Hildenbrand (Arm) wrote: >> On 10/2/26 12:02, David Hildenbrand (Arm) wrote: >>> >>> Yes, I'll take care of it. >>> >>> [...] >>> >>> After sending this yesterday, I concluded that we can do this cleaner: just have >>> >>> bool normal_page; >>> >>> (naming suggestions?) >>> >>> that express that this is something refcounted with a struct page, like >>> documented for vm_normal_page(). >> >> Hmm, have to think about that once more, regarding VM_IO and if there are some >> cases that would actually have to work in generic_access_phys(). > > Well, my series at least makes it easier to reason about VMA_IO_BIT! > > Though not sure if it really touches PFN map cases specifically. I'm more concerned about someone using this function on VM_MIXEDMAP | VM_IO with a memory page that has a struct page but is actually not memory. So we could get something that vm_normal_page() would flag but generic_access_phys() could actually read ... I'll have to explore the generic_access_phys() users once more. All way to complicated (and you series improves things). -- Cheers, David