From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com (mail-pd0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id 012946B0070 for ; Sun, 26 Oct 2014 23:23:39 -0400 (EDT) Received: by mail-pd0-f180.google.com with SMTP id ft15so2851903pdb.11 for ; Sun, 26 Oct 2014 20:23:39 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTP id hs2si9363422pdb.222.2014.10.26.20.23.38 for ; Sun, 26 Oct 2014 20:23:38 -0700 (PDT) Message-ID: <544DBA03.1010709@intel.com> Date: Mon, 27 Oct 2014 11:20:35 +0800 From: Ren Qiaowei MIME-Version: 1.0 Subject: Re: [PATCH v9 05/12] x86, mpx: on-demand kernel allocation of bounds tables References: <1413088915-13428-1-git-send-email-qiaowei.ren@intel.com> <1413088915-13428-6-git-send-email-qiaowei.ren@intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: "H. Peter Anvin" , Ingo Molnar , Dave Hansen , x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-mips@linux-mips.org On 10/24/2014 08:08 PM, Thomas Gleixner wrote: > On Sun, 12 Oct 2014, Qiaowei Ren wrote: >> + /* >> + * Go poke the address of the new bounds table in to the >> + * bounds directory entry out in userspace memory. Note: >> + * we may race with another CPU instantiating the same table. >> + * In that case the cmpxchg will see an unexpected >> + * 'actual_old_val'. >> + */ >> + ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry, >> + expected_old_val, bt_addr); > > This is fully preemptible non-atomic context, right? > > So this wants a proper comment, why using > user_atomic_cmpxchg_inatomic() is the right thing to do here. > Well, we will address it. Thanks, Qiaowei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org