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Mon, 03 Aug 2026 12:52:52 -0400 X-MC-Unique: IL494TFFOpGy18qDZDNHmg-1 X-Mimecast-MFC-AGG-ID: IL494TFFOpGy18qDZDNHmg_1785775970 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3F4011956069; Mon, 3 Aug 2026 16:52:50 +0000 (UTC) Received: from [10.44.48.18] (unknown [10.44.48.18]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 38B111956087; Mon, 3 Aug 2026 16:52:45 +0000 (UTC) Message-ID: Date: Mon, 3 Aug 2026 18:52:41 +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 RFT 0/3] mm, drm: ensure .fault() does not have to be followed by .pfn_mkwrite() for write faults To: "David Hildenbrand (Arm)" , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Boris Brezillon , Thomas Zimmermann , Michal Hocko , Sergio Lopez , Christian Koenig , Huang Rui , bcm-kernel-feedback-list@broadcom.com, dri-devel@lists.freedesktop.org, linux-mm@kvack.org References: <20260731164341.1109827-1-pbonzini@redhat.com> <8d94897f-0f56-4ecf-bcc8-50bffd6750b2@kernel.org> From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 On 8/3/26 10:55, David Hildenbrand (Arm) wrote: > On 7/31/26 18:05, Paolo Bonzini wrote: >> Reported-by: Sergio Lopez > > Reported-by: without Fixes: is odd. Fixes: 6da8e9634bb7 ("mm: new follow_pfnmap API") would also be odd :) but I can certainly add it. >> + * @write_fault: if true, fail with -EFAULT unless the mapping is > > Just wondering whether EPERM would be better. It would be EACCES if anything, not EPERM; but almost all callers already pass EFAULT to userspace, and write() to a PROT_READ area returns EFAULT, so I don't think EACCES is the right choice. >> + * writable >> */ >> struct vm_area_struct *vma; >> unsigned long address; >> + bool write_fault; > > "write_fault" is a rather odd name for this, given that this function will not > trigger a write fault. > > You want something that matches FOLL_WRITE. > > "write_access" / "check_writable" maybe? There are no for_write, write_access or check_write in mm/, but there are a handful of each of these int write = (gup_flags & FOLL_WRITE); bool write = vmf->flags & FAULT_FLAG_WRITE; so I'll go for just "write". Thanks, Paolo