From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb0-f200.google.com (mail-yb0-f200.google.com [209.85.213.200]) by kanga.kvack.org (Postfix) with ESMTP id 6F8096B02C3 for ; Mon, 19 Jun 2017 15:59:54 -0400 (EDT) Received: by mail-yb0-f200.google.com with SMTP id l2so85047310ybb.6 for ; Mon, 19 Jun 2017 12:59:54 -0700 (PDT) Received: from userp1040.oracle.com (userp1040.oracle.com. [156.151.31.81]) by mx.google.com with ESMTPS id v184si2954630ybv.369.2017.06.19.12.59.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Jun 2017 12:59:53 -0700 (PDT) Date: Mon, 19 Jun 2017 15:59:35 -0400 From: "Liam R. Howlett" Subject: Re: [PATCH] mm/hugetlb: Warn the user when issues arise on boot due to hugepages Message-ID: <20170619195935.tymymev7bntslxci@oracle.com> References: <20170605151541.avidrotxpoiekoy5@oracle.com> <20170606054917.GA1189@dhcp22.suse.cz> <20170606060147.GB1189@dhcp22.suse.cz> <20170612172829.bzjfmm7navnobh4t@oracle.com> <20170612174911.GA23493@dhcp22.suse.cz> <20170612183717.qgcusdfvdfcj7zr7@oracle.com> <20170612185208.GC23493@dhcp22.suse.cz> <20170613013516.7fcmvmoltwhxmtmp@oracle.com> <20170616120755.c56d205f49d93a6e3dffb14f@linux-foundation.org> <20170617065141.GB26698@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170617065141.GB26698@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, mike.kravetz@Oracle.com, n-horiguchi@ah.jp.nec.com, aneesh.kumar@linux.vnet.ibm.com, gerald.schaefer@de.ibm.com, zhongjiang@huawei.com, aarcange@redhat.com, kirill.shutemov@linux.intel.com * Michal Hocko [170617 02:51]: > On Fri 16-06-17 12:07:55, Andrew Morton wrote: > > On Mon, 12 Jun 2017 21:35:17 -0400 "Liam R. Howlett" wrote: > > > > > > > > > > > If there's no message stating any > > > > > configuration issue, then many admins would probably think something is > > > > > seriously broken and it's not just a simple typo of K vs M. > > > > > > > > > > Even though this doesn't catch all errors, I think it's a worth while > > > > > change since this is currently a silent failure which results in a > > > > > system crash. > > > > > > > > Seriously, this warning just doesn't help in _most_ miscofigurations. It > > > > just focuses on one particular which really requires to misconfigure > > > > really badly. And there are way too many other ways to screw your system > > > > that way, yet we do not warn about many of those. So just try to step > > > > back and think whether this is something we actually do care about and > > > > if yes then try to come up with a more reasonable warning which would > > > > cover a wider range of misconfigurations. > > > > > > Understood. Again, I appreciate all the time you have taken on my > > > patch and explaining your points. I will look at this again as you > > > have suggested. > > > > So do we want to drop > > mm-hugetlb-warn-the-user-when-issues-arise-on-boot-due-to-hugepages.patch? > > > > I'd be inclined to keep it if Liam found it a bit useful - it does have > > some overhead, but half the patch is in __init code... > > I would rather see a more generic warning that would catch more > misconfiguration than those ultimately broken ones. If we find out that > such a warning is not feasible then I would not oppose to go with the > current approach but let's try a bit harder before we go that way. > > Liam, are you willing to go that way? As I see it, and as you have pointed out, we can only be sure it's an error if it's over 100% of the memory. Although it's certainly worth while looking for a way to detect an incorrect configuration that doesn't meet this criteria, I'm not sure it's worth holding out to make the change. I think giving any direct message could save someone a lot of debug time. If it's okay, I'd like to go ahead with the change and also look for a way to correct and notify of a broader range of configurations that cause severe issues in regards to hugepages. Thanks, Liam -- 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