From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 B80E1352C4F for ; Wed, 11 Feb 2026 19:37:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770838654; cv=none; b=OJpG/JHW309YgwEC+KynSUCbRBS5zNXhkacDmpYQVPn40hbWJD8UkKHg/AWmakMtQrIxX8aayGyJnVXMljG4U5jk3bmYVQtrJ2plSLx7Ht/q5aOVFRaROu9TbUppInxZbTfmaJ++zPogNzm411WQm0TtPatjOeNlChwtqMj/fw8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770838654; c=relaxed/simple; bh=9E8xym4kPqUtQ4zv5yeII+4X0aDlSLDVsQXEk9VD660=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uVtN3FOwuFL8zwcWq7+9Mv2tXxCQjYW0ySLPsSbPVefgm7F/9GmYgzkG9oi+qRAzuDQRKMaLoe3CRU1TiICnss8RiVqR2jy50qUQvkerx6SGyBpWb+6/GZwlTYxxFgCXXZVk5o0jRF6h2WDXOWIaIo4smvlmtRgNs82AvWK0MOA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ihwN/HIR; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=J+MuA8SH; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ihwN/HIR"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="J+MuA8SH" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770838650; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3HnSln6BmAeJW+dBA3yyxX0sDcUZ80hLGHPfC7uKPVU=; b=ihwN/HIRHg+g6mpBpmGJ8eY6bzSpWKrv+syfIgYaD/dsg/zzxCkpNZwLaFRTszNuyXFCUF xz0CF3gR+EmOukogDW4fSjaO+sWWWEvg0LUdwfyKvwx/oIV6CnMO/q6pWBG3l9lIWVl8Qq Ed7b+o8Bm9G+HW3QhZSeSgLzjXIg8as= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-182-ERR2gxUJN3OPL0ek1uxfDg-1; Wed, 11 Feb 2026 14:37:29 -0500 X-MC-Unique: ERR2gxUJN3OPL0ek1uxfDg-1 X-Mimecast-MFC-AGG-ID: ERR2gxUJN3OPL0ek1uxfDg_1770838649 Received: by mail-qk1-f198.google.com with SMTP id af79cd13be357-8c6ad709d8fso306526785a.1 for ; Wed, 11 Feb 2026 11:37:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1770838649; x=1771443449; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=3HnSln6BmAeJW+dBA3yyxX0sDcUZ80hLGHPfC7uKPVU=; b=J+MuA8SHYGyELefHY2x7cOLzx67VNAKone7JYxXA7217PwFt94YzzuSs16VE6897Jn qpUAhSRKrS5xZRCdkp7VR/uOxMFW1zGoMz1lkyYkWJxz9Uod17sJD4di5Mnkipokpf1W 8hKU4yxDQLF4SWACdXLnWFua5UoQkgrYn3PWpCGRes6AXA56PQhGLv3RwGgDax298ULt 7Uo+yEllsuuBsD+nkoeEktYUIjaxeUOdo6VeTcZY5kQls3NbBisNf4190cX+B+/LDwbZ UP8oO6rJ/TCQyCw1DTtGW+2Pp4TUwDm9z2YnNaJzt1cXcChd9Y+uziYwN0SIYkaM1OMO hXTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770838649; x=1771443449; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3HnSln6BmAeJW+dBA3yyxX0sDcUZ80hLGHPfC7uKPVU=; b=C1JXjEjk2d9dvgjCjz7yaeQH7epRvfpQGeHkyit7wOytGYageXQnpTwXprGXvcMo4k /cZRfkFak1pju71K5HJjvqgF5IcuJF7HoM/euadvHVgbWoYagyNBr6ecsXNIIOJG7nS1 bVvC1dU9f3YMtdP5xsinOEjegQ41Ipte8qLdQssJgducMOtO3WWp8LG9zuLQQGy7P3Fl pjawwmH8wyxnHiLm4mKk1fWGQSEOvgX4Xkr2E3Izbu97qqcZ7lduZSlhI+kLNfnYuiRd puF6DazJBLodwaEbaDqaTOKRw7sqTYPqM7kLDaFYVmAjfxnI3FN6JblPr2MP58CFEYJ9 t0Bw== X-Forwarded-Encrypted: i=1; AJvYcCXoXBuiQrwsOzNAcwSaxrJXILK0yE3vt1fIk9xKelZ+GxoF5AAQRsSUxo0lyMeYt57d2ESOYN8iox7j1LqWXV4=@vger.kernel.org X-Gm-Message-State: AOJu0Yy54CZxdILeL5RnaQwuUaa/WRJujLpgvzIINMgvc/0RHYPN7aON rHsRkbppvrkFKjYKPPhIrg/9SYpGGDslzDww0M95gZfoD/y/B8dB3QvSUrbt8AYp2Arelv3Sd7R ftg5uGCkJdUpwMTMw4ZrYUfobltZ+HjhcPMFP9rnUxzXHvogcX5tLNPSmnOJPWqxKnvTe9Q== X-Gm-Gg: AZuq6aK6ko3MWkPs8KsPefwT7+yl6qiJcRtt5UJhQW/QhyEYRkXJwDsbvavqUtTj0If xuGjFvE51k0fCC1VWJV0w+sqh+wPMfSRmBrib28fv+zjGtmlN3KsxzOkzjFwZEa/zuQMWletsrn Q2inTFGxRBQxeIZD1gOBriTUwDNfqhJg473wFV+3uskcH74AjfRn51kBdCdoOC6aeHwzB9cE45j uL+ON3Xdhri04o93QTR5V/nbMWl78KRhNft4Kc6st81utXMrqNEsZriKhtxV6mjfHjRQUvt9q38 Ow2t2ek4gyq/xR3JK3scDqUf+nAzFsX84n8+ms9YiB60c9mgSnGAtm0Vj5/Wjo6iYBID1SEtlaP HB6Xic+F9K2Vb/cnIM6kCFS91Ey+SPhKt+8OBgYlAI3A9RrZwARywpf7DZVOS62S0N/E/FOUEb0 Ga2za7QA== X-Received: by 2002:a05:620a:bcd:b0:8c7:110e:9cd5 with SMTP id af79cd13be357-8cb33d8c6fdmr4445285a.45.1770838649071; Wed, 11 Feb 2026 11:37:29 -0800 (PST) X-Received: by 2002:a05:620a:bcd:b0:8c7:110e:9cd5 with SMTP id af79cd13be357-8cb33d8c6fdmr4438985a.45.1770838648496; Wed, 11 Feb 2026 11:37:28 -0800 (PST) Received: from x1.local (bras-vprn-aurron9134w-lp130-03-174-91-117-149.dsl.bell.ca. [174.91.117.149]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8971cd8aff6sm21074646d6.27.2026.02.11.11.37.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 11:37:28 -0800 (PST) Date: Wed, 11 Feb 2026 14:37:26 -0500 From: Peter Xu To: Mike Rapoport Cc: linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 09/17] userfaultfd: introduce vm_uffd_ops->alloc_folio() Message-ID: References: <20260127192936.1250096-1-rppt@kernel.org> <20260127192936.1250096-10-rppt@kernel.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Sun, Feb 08, 2026 at 12:22:52PM +0200, Mike Rapoport wrote: > On Mon, Feb 02, 2026 at 05:13:20PM -0500, Peter Xu wrote: > > On Tue, Jan 27, 2026 at 09:29:28PM +0200, Mike Rapoport wrote: > > > > [...] > > > > > -static int mfill_atomic_pte_zeroed_folio(pmd_t *dst_pmd, > > > - struct vm_area_struct *dst_vma, > > > - unsigned long dst_addr) > > > +static int mfill_atomic_pte_copy(struct mfill_state *state) > > > { > > > - struct folio *folio; > > > - int ret = -ENOMEM; > > > - > > > - folio = vma_alloc_zeroed_movable_folio(dst_vma, dst_addr); > > > - if (!folio) > > > - return ret; > > > - > > > - if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL)) > > > - goto out_put; > > > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma); > > > > > > - /* > > > - * The memory barrier inside __folio_mark_uptodate makes sure that > > > - * zeroing out the folio become visible before mapping the page > > > - * using set_pte_at(). See do_anonymous_page(). > > > - */ > > > - __folio_mark_uptodate(folio); > > > + return __mfill_atomic_pte(state, ops); > > > +} > > > > > > - ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr, > > > - &folio->page, true, 0); > > > - if (ret) > > > - goto out_put; > > > +static int mfill_atomic_pte_zeroed_folio(struct mfill_state *state) > > > +{ > > > + const struct vm_uffd_ops *ops = vma_uffd_ops(state->vma); > > > > > > - return 0; > > > -out_put: > > > - folio_put(folio); > > > - return ret; > > > + return __mfill_atomic_pte(state, ops); > > > } > > > > > > static int mfill_atomic_pte_zeropage(struct mfill_state *state) > > > @@ -542,7 +546,7 @@ static int mfill_atomic_pte_zeropage(struct mfill_state *state) > > > int ret; > > > > > > if (mm_forbids_zeropage(dst_vma->vm_mm)) > > > - return mfill_atomic_pte_zeroed_folio(dst_pmd, dst_vma, dst_addr); > > > + return mfill_atomic_pte_zeroed_folio(state); > > > > After this patch, mfill_atomic_pte_zeroed_folio() should be 100% the same > > impl with mfill_atomic_pte_copy(), so IIUC we can drop it. > > It will be slightly different after the next patch to emphasize that > copying into MAP_PRIVATE actually creates anonymous memory. True. It might be helpful to leave a line in the commit message so it's intentional to temporarily have two functions do the same thing, but I'm OK either way. Thanks, -- Peter Xu