From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2BF313C3422; Thu, 9 Apr 2026 11:56:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775735812; cv=none; b=peindD6IWkehRlRq4eIxJ+mmsAwghADLRYyK6vwi2ABxYxMaJ7EgKhVnuo6jzwRKgx3zbjQ+pc+sH4ZQY1cOXa/iqTw8N0Yr1+2RcgrSNLIsv9wpiF5iRZvnTgnModXqMalW1Qz5y8WLIVUwZxd3ad9XZmIDU7R65pxuz+yws8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775735812; c=relaxed/simple; bh=y7BqNP1W2KHlU19MlaW9q/B2IueRNczxl1oFvHsBkhY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jMj+NZm/k8lv+2HnavmR8vZXmoYEUR3A8RxxVs6hbgL7xLxFMRpFpAXHH5rRcC+cF5tpIrAZf0aw8FZYbIILT10HuYvcIm9wSMxOf20yF9NJAOhvkBLGOfqFiqXqA1hPWMx0ouK4h71TI8R/1Kjrhrj7Yt2Wt7woyJtXvpPME38= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cBaBeupr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cBaBeupr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C506C4CEF7; Thu, 9 Apr 2026 11:56:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775735811; bh=y7BqNP1W2KHlU19MlaW9q/B2IueRNczxl1oFvHsBkhY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cBaBeuprHZm72wS3WWjG/PSuQyvKttdSOA1j/vK6PgAhE7Lsj4gmjD878J/MRzNEC 5oJoD2FcJ4OXH1yIHVfmZuhzBpQmC2/9TAy/Lp08swOsFcAg0VcfdesDv0k6jl/TuI XT9azHwufArq+ht+v4XCMoV2YhdajSjejTegQ/rMas9hAZomilsEQzEhSdEDu3cC72 a7k8WsSeNJZx/MsHsnyYhMFntLXV3S11rIwOaDsd1ND0ekP8dlyImVQHyyRwrw8t/Q jjYDSiaa8Q+1lcs4dlPdBM2amiK1ig8anEMJo0gAS4xKzuA4PbnFq3htCofpI/VPgr U0o2gzxhpHdtA== Date: Thu, 9 Apr 2026 20:56:49 +0900 From: "Harry Yoo (Oracle)" To: "Denis M. Karpov" Cc: rppt@kernel.org, akpm@linux-foundation.org, Liam.Howlett@oracle.com, ljs@kernel.org, vbabka@kernel.org, jannh@google.com, peterx@redhat.com, pfalcato@suse.de, brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, usama.arif@linux.dev Subject: Re: [PATCH v2] userfaultfd: allow registration of ranges below mmap_min_addr Message-ID: References: <20260409103345.15044-1-komlomal@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <20260409103345.15044-1-komlomal@gmail.com> On Thu, Apr 09, 2026 at 01:33:45PM +0300, Denis M. Karpov wrote: > The current implementation of validate_range() in fs/userfaultfd.c > performs a hard check against mmap_min_addr. This is redundant because > UFFDIO_REGISTER operates on memory ranges that must already be backed > by a VMA. > > Enforcing mmap_min_addr or capability checks again in userfaultfd is > unnecessary and prevents applications like binary compilers from > using UFFD for valid memory regions mapped by application. > > Remove the redundant check for mmap_min_addr. > > Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") > Signed-off-by: Denis M. Karpov > --- > v2: > - Remove the check entirely rather than replacing it, as suggested by > Harry Yoo and Lorenzo Stoakes. > - Added Fixes tag. > - Link to v1: https://lore.kernel.org/r/20260407081442.6256-1-komlomal@gmail.com > --- Looks good to me, Acked-by: Harry Yoo (Oracle) -- Cheers, Harry / Hyeonggon