Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753105AbaAVH30 (ORCPT ); Wed, 22 Jan 2014 02:29:26 -0500 Received: from mail-pb0-f48.google.com ([209.85.160.48]:45509 "EHLO mail-pb0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750873AbaAVH3Z (ORCPT ); Wed, 22 Jan 2014 02:29:25 -0500 Date: Tue, 21 Jan 2014 23:29:14 -0800 From: Steven Noonan To: Konrad Rzeszutek Wilk Cc: boris.ostrovsky@oracle.com, david.vrabel@citrix.com, xen-devel@lists.xenproject.org, george.dunlap@eu.citrix.com, dario.faggioli@citrix.com, Elena Ufimtseva , Linus Torvalds , Greg Kroah-Hartman , Andrea Arcangeli , "Kirill A. Shutemov" , Linux Kernel mailing List , Mel Gorman , Rik van Riel , Alex Thorlton , Andrew Morton Subject: Re: [BISECTED] Linux 3.12.7 introduces page map handling regression Message-ID: <20140122072914.GA9283@orcus.uplinklabs.net> References: <20140121232708.GA29787@amazon.com> <20140122014908.GG18164@kroah.com> <20140122032045.GA22182@falcon.amazon.com> <20140122050215.GC9931@konrad-lan.dumpdata.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140122050215.GC9931@konrad-lan.dumpdata.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 22, 2014 at 12:02:15AM -0500, Konrad Rzeszutek Wilk wrote: > On Tue, Jan 21, 2014 at 07:20:45PM -0800, Steven Noonan wrote: > > On Tue, Jan 21, 2014 at 06:47:07PM -0800, Linus Torvalds wrote: > > > On Tue, Jan 21, 2014 at 5:49 PM, Greg Kroah-Hartman > > > wrote: > > Adding extra folks to the party. > > > > > > > > Odds are this also shows up in 3.13, right? > > > > Reproduced using 3.13 on the PV guest: > > > > [ 368.756763] BUG: Bad page map in process mp pte:80000004a67c6165 pmd:e9b706067 > > [ 368.756777] page:ffffea001299f180 count:0 mapcount:-1 mapping: (null) index:0x0 > > [ 368.756781] page flags: 0x2fffff80000014(referenced|dirty) > > [ 368.756786] addr:00007fd1388b7000 vm_flags:00100071 anon_vma:ffff880e9ba15f80 mapping: (null) index:7fd1388b7 > > [ 368.756792] CPU: 29 PID: 618 Comm: mp Not tainted 3.13.0-ec2 #1 > > [ 368.756795] ffff880e9b718958 ffff880e9eaf3cc0 ffffffff814d8748 00007fd1388b7000 > > [ 368.756803] ffff880e9eaf3d08 ffffffff8116d289 0000000000000000 0000000000000000 > > [ 368.756809] ffff880e9b7065b8 ffffea001299f180 00007fd1388b8000 ffff880e9eaf3e30 > > [ 368.756815] Call Trace: > > [ 368.756825] [] dump_stack+0x45/0x56 > > [ 368.756833] [] print_bad_pte+0x229/0x250 > > [ 368.756837] [] unmap_single_vma+0x583/0x890 > > [ 368.756842] [] unmap_vmas+0x65/0x90 > > [ 368.756847] [] unmap_region+0xac/0x120 > > [ 368.756852] [] ? vma_rb_erase+0x1c9/0x210 > > [ 368.756856] [] do_munmap+0x280/0x370 > > [ 368.756860] [] vm_munmap+0x41/0x60 > > [ 368.756864] [] SyS_munmap+0x22/0x30 > > [ 368.756869] [] system_call_fastpath+0x1a/0x1f > > [ 368.756872] Disabling lock debugging due to kernel taint > > [ 368.760084] BUG: Bad rss-counter state mm:ffff880e9d079680 idx:0 val:-1 > > [ 368.760091] BUG: Bad rss-counter state mm:ffff880e9d079680 idx:1 val:1 > > > > > > > > Probably. I don't have a Xen PV setup to test with (and very little > > > interest in setting one up).. And I have a suspicion that it might not > > > be so much about Xen PV, as perhaps about the kind of hardware. > > > > > > I suspect the issue has something to do with the magic _PAGE_NUMA > > > tie-in with _PAGE_PRESENT. And then mprotect(PROT_NONE) ends up > > > removing the _PAGE_PRESENT bit, and now the crazy numa code is > > > confused. > > > > > > The whole _PAGE_NUMA thing is a f*cking horrible hack, and shares the > > > bit with _PAGE_PROTNONE, which is why it then has that tie-in to > > > _PAGE_PRESENT. > > > > > > Adding Andrea to the Cc, because he's the author of that horridness. > > > Putting Steven's test-case here as an attachement for Andrea, maybe > > > that makes him go "Ahh, yes, silly case". > > > > > > Also added Kirill, because he was involved the last _PAGE_NUMA debacle. > > > > > > Andrea, you can find the thread on lkml, but it boils down to commit > > > 1667918b6483 (backported to 3.12.7 as 3d792d616ba4) breaking the > > > attached test-case (but apparently only under Xen PV). There it > > > apparently causes a "BUG: Bad page map .." error. > > I *think* it is due to the fact that pmd_numa and pte_numa is getting the _raw_ > value of PMDs and PTEs. That is - it does not use the pvops interface > and instead reads the values directly from the page-table. Since the > page-table is also manipulated by the hypervisor - there are certain > flags it also sets to do its business. It might be that it uses > _PAGE_GLOBAL as well - and Linux picks up on that. If it was using > pte_flags that would invoke the pvops interface. > > Elena, Dariof and George, you guys had been looking at this a bit deeper > than I have. Does the Xen hypervisor use the _PAGE_GLOBAL for PV guests? > > This not-compiled-totally-bad-patch might shed some light on what I was > thinking _could_ fix this issue - and IS NOT A FIX - JUST A HACK. > It does not fix it for PMDs naturally (as there are no PMD paravirt ops > for that). Unfortunately the Totally Bad Patch seems to make no difference. I am still able to repro the issue: [ 346.374929] BUG: Bad page map in process mp pte:80000004ae928065 pmd:e993f9067 [ 346.374942] page:ffffea0012ba4a00 count:0 mapcount:-1 mapping: (null) index:0x0 [ 346.374946] page flags: 0x2fffff80000014(referenced|dirty) [ 346.374951] addr:00007f06a9bbb000 vm_flags:00100071 anon_vma:ffff880e9939fe00 mapping: (null) index:7f06a9bbb [ 346.374956] CPU: 29 PID: 609 Comm: mp Not tainted 3.13.0-ec2+ #1 [ 346.374960] ffff880e9cc38da8 ffff880e991a3cc0 ffffffff814d8768 00007f06a9bbb000 [ 346.374967] ffff880e991a3d08 ffffffff8116d289 0000000000000000 0000000000000000 [ 346.374972] ffff880e993f9dd8 ffffea0012ba4a00 00007f06a9bbc000 ffff880e991a3e30 [ 346.374979] Call Trace: [ 346.374988] [] dump_stack+0x45/0x56 [ 346.374996] [] print_bad_pte+0x229/0x250 [ 346.375000] [] unmap_single_vma+0x583/0x890 [ 346.375006] [] unmap_vmas+0x65/0x90 [ 346.375011] [] unmap_region+0xac/0x120 [ 346.375016] [] ? vma_rb_erase+0x1c9/0x210 [ 346.375021] [] do_munmap+0x280/0x370 [ 346.375025] [] vm_munmap+0x41/0x60 [ 346.375029] [] SyS_munmap+0x22/0x30 [ 346.375034] [] system_call_fastpath+0x1a/0x1f [ 346.375037] Disabling lock debugging due to kernel taint [ 346.380082] BUG: Bad rss-counter state mm:ffff880e9d22bc00 idx:0 val:-1 [ 346.380088] BUG: Bad rss-counter state mm:ffff880e9d22bc00 idx:1 val:1 This dump doesn't look dramatically different, either. > > The other question is - how is AutoNUMA running when it is not enabled? > Shouldn't those _PAGE_NUMA ops be nops when AutoNUMA hasn't even been > turned on? Well, NUMA_BALANCING is enabled in the kernel config[1], but I presume you mean not enabled at runtime? [1] http://git.uplinklabs.net/snoonan/projects/archlinux/ec2/ec2-packages.git/tree/linux-ec2/config.x86_64 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/