From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id 104746B0279 for ; Wed, 7 Jun 2017 10:49:17 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id b19so2624964qkj.10 for ; Wed, 07 Jun 2017 07:49:17 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id y10si2226261qth.35.2017.06.07.07.49.16 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Jun 2017 07:49:16 -0700 (PDT) Date: Wed, 7 Jun 2017 10:49:12 -0400 From: Jerome Glisse Subject: Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove Message-ID: <20170607144912.GA6639@redhat.com> References: <20170606173512.7378-1-jglisse@redhat.com> <20170607104715.5niuwk42fhahbftk@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170607104715.5niuwk42fhahbftk@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andy Lutomirski , Ingo Molnar , "Kirill A . Shutemov" , Logan Gunthorpe On Wed, Jun 07, 2017 at 01:47:15PM +0300, Kirill A. Shutemov wrote: > On Tue, Jun 06, 2017 at 01:35:12PM -0400, Jerome Glisse wrote: > > With commit af2cf278ef4f we no longer free pud so that we > > do not have synchronize all pgd on hotremove/vfree. But the > > new 5 level page table code re-added that code f2a6a705 and > > thus we now trigger a BUG_ON() l128 in sync_global_pgds() > > > > This patch remove free_pud() like in af2cf278ef4f > > Good catch. Thanks! > > But I think we only need to skip free_pud_table() for 4-level paging. > If we don't we would leave 513 page tables around instead of one in > 5-level paging case. > > I don't think it's acceptable. > > And please use patch subject lines along with commit hashes to simplify > reading commit message. > I sent a v2 that disable free_pud in 4 level page table config. Note that your patchset that allow switching between 4 and 5 at boot time will need to update that code. As this patch is a fix and your boot time switching is an RFC i assume the fix will go in first. Cheers, Jerome -- 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