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 E012B4E1414; Thu, 15 Oct 2026 09:05:31 +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=1792055132; cv=none; b=RpaM0Cdxoyy1CsSZVJa6qo3eZk9AISlyrm9iL5SM4znP9JVnXUgs3R08ZfotEBC+ty3cMofui8mvUIw0UxOwd6RF9opuOQDymv64lDhPBeXYphUKcvIrokfoYOoQG8np/nQgewnl3FS711eQpcoBEt6yX8meVu2J+3Jcyz64EG4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792055132; c=relaxed/simple; bh=i3Iy2xLXR2x993pIXgHnMySyaQglTta+do5lmMI7ybk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dJRTjHZkBVOUsq4CMXMI0nwtgxvfUTJC0bv0rdm9WuDCpFVs5V+Lh+NCNVl6HC4HiaXrrHNWORfdcbHev7eRobinEv6LfkPAtT+psLAkZbgxhq55YlDj0lHElMThPENERf9ItkM+3diejnqRrSmFsKLtFljaxJ+UVsJQmjJCaJs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BjxGIpPy; 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="BjxGIpPy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B99B41F000C5; Thu, 15 Oct 2026 09:05:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792055131; bh=i3Iy2xLXR2x993pIXgHnMySyaQglTta+do5lmMI7ybk=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=BjxGIpPytUDCjf3oHieq1z2xj+WqtcBnVttFrOgOeGtnR4dXibxnqiymN9qUS4FVQ UZcwaO9d5rTLZcjDX8/WxaJ0OPnfXjEwQbP4YTJaQISyEupwW2HCHUydxT2PUolM3T E91G+9KoXO+i+UtEff3VNmqcGtiqf5oiA59PYznQqEJGTo45KIvOBSUpd59/jgc60N cpudvdzDyKTz3G0wt6wK2dboL19osEtYvZbZMPQ2aLGuRfeyxxOft7bF+wspbZO6Zl BasBxay/SBgmeCqOzjjzapcDi7ghmQlto+QvjvuIEvoKzBxtuCCsxhZZJjeG+SKwJT 8D2smjU76jMdQ== Date: Thu, 15 Oct 2026 10:05:24 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Muchun Song , Oscar Salvador , Andrew Morton , Mike Rapoport , Peter Xu , Miaohe Lin , Lokesh Gidra , "Liam R. Howlett" , Kyle Zeng , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/userfaultfd: only allocate anon_vma in CoW mappings Message-ID: References: <20261014-copy_hugetlb_page_range-v1-1-5b68e03fe7fe@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Oct 14, 2026 at 08:29:35PM +0200, David Hildenbrand (Arm) wrote: > > Hmm really? Is it possible to do that without the hugetlb lock? > > Yes, we don't have to sync against PMD sharing if PMD sharing is impossible. Ahhh I see. > Will send that out for the next cycle. Looks sane! > > > It'd be good in general if we could get rid of that lock as a whole :) but maybe > > dreaming. > > Yeah :) I will probably have to go and look at that more deeply for mmap_prepare/scalable CoW reasons. I will wear goggles... :) -- Cheers, Lorenzo