From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756198Ab3AIAFO (ORCPT ); Tue, 8 Jan 2013 19:05:14 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:40416 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755944Ab3AIAFI (ORCPT ); Tue, 8 Jan 2013 19:05:08 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Yinghai Lu Cc: Shuah Khan , Konrad Rzeszutek Wilk , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrew Morton , Borislav Petkov , Jan Kiszka , Jason Wessel , linux-kernel@vger.kernel.org, Joerg Roedel References: <1357260531-11115-1-git-send-email-yinghai@kernel.org> <1357260531-11115-27-git-send-email-yinghai@kernel.org> <20130107152622.GD3219@phenom.dumpdata.com> <8762382z2c.fsf@xmission.com> <87y5g4z7rp.fsf@xmission.com> Date: Tue, 08 Jan 2013 16:04:52 -0800 In-Reply-To: (Yinghai Lu's message of "Tue, 8 Jan 2013 15:40:11 -0800") Message-ID: <874nirz0ez.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-AID: U2FsdGVkX1/DLReH/Np7Kjo6eLn+kqJiSqerFVjV2mA= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 2.9 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list * 3.0 XMDrug1234561 Drug references * 0.1 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0005] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;Yinghai Lu X-Spam-Relay-Country: Subject: Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is not enough ram for it X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Wed, 14 Nov 2012 14:26:46 -0700) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yinghai Lu writes: > On Mon, Jan 7, 2013 at 7:50 PM, Yinghai Lu wrote: >> On Mon, Jan 7, 2013 at 7:13 PM, Eric W. Biederman wrote: >>> I meant we should detect failure to allocate bounce buffers in in >>> swiotlb_init() instead of panicing. >>> >>> I meant swiotlb_map_single() should either panic or simply fail. >>> >>> If I have read lib/swiotlb.c correctly the only place we allocate a >>> bounce buffer is in swiotlb_map_single. If there are more places we can >>> allocate bounce buffers those need to be handled as well. >> >> ok, will give it a try. > > please check if you are ok with attached. > It looks like the right direction. Certainly enough to test and see if the code will work. I don't see the point of adding a nopanic case to the swiotlb initialization. That just looks like unnecessary complications. Certainly a nopanic case implemented by passing a nopanic parameter looks like the wrong way to go. At most you want to return an error code and do: swiotlb_init() { if (swiotlb_init_with_default_size() == -ENOMEM) panic("Cannot allocate SWIOTLB buffer"); } The page freeing in swiotlb_init_with_tbl appears to be in the wrong function. I suggest looking at swiotlb_late_init which apparently is allowed to fail for some ideas. > looks like it need more change of lines. The size of the change matters less than how clean and maintainable the result is. If done carefully I expect you can have net fewer lines but not needing to handle the case when the swiotlb apis are unavailable. Eric