Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755028AbaAWXUW (ORCPT ); Thu, 23 Jan 2014 18:20:22 -0500 Received: from mail-pb0-f50.google.com ([209.85.160.50]:56442 "EHLO mail-pb0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752578AbaAWXUU (ORCPT ); Thu, 23 Jan 2014 18:20:20 -0500 Date: Thu, 23 Jan 2014 15:20:12 -0800 From: Steven Noonan To: Elena Ufimtseva Cc: Daniel Borkmann , Konrad Rzeszutek Wilk , Boris Ostrovsky , David Vrabel , xen-devel , George Dunlap , Dario Faggioli , Linus Torvalds , Greg Kroah-Hartman , Andrea Arcangeli , "Kirill A. Shutemov" , Linux Kernel mailing List , Mel Gorman , Rik van Riel , Alex Thorlton , Andrew Morton , Vlastimil Babka , Michel Lespinasse Subject: Re: [BISECTED] Linux 3.12.7 introduces page map handling regression Message-ID: <20140123232012.GA23046@orcus.uplinklabs.net> References: <20140121232708.GA29787@amazon.com> <20140122014908.GG18164@kroah.com> <20140122032045.GA22182@falcon.amazon.com> <20140122050215.GC9931@konrad-lan.dumpdata.com> <20140122072914.GA9283@orcus.uplinklabs.net> <52DFD5DB.6060603@iogearbox.net> <20140122203337.GA31908@orcus.uplinklabs.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Thu, Jan 23, 2014 at 11:23:37AM -0500, Elena Ufimtseva wrote: > On Wed, Jan 22, 2014 at 3:33 PM, Steven Noonan wrote: > > On Wed, Jan 22, 2014 at 03:18:50PM -0500, Elena Ufimtseva wrote: > >> On Wed, Jan 22, 2014 at 9:29 AM, Daniel Borkmann wrote: > >> > On 01/22/2014 08:29 AM, Steven Noonan wrote: > >> >> > >> >> 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? > > It does use _PAGE_GLOBAL for guest user pages > > >> >>> > >> >>> 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: > >> > >> Steven, do you use numa=fake on boot cmd line for pv guest? > >> > >> I had similar issue on pv guest. Let me check if the fix that resolved > >> this for me will help with 3.13. > > > > Nope: > > > > # cat /proc/cmdline > > root=/dev/xvda1 ro rootwait rootfstype=ext4 nomodeset console=hvc0 earlyprintk=xen,verbose loglevel=7 > > > > >> > >> > > >> > > >> > Maybe this one is also related to this BUG here (cc'ed people investigating > >> > this one) ... > >> > > >> > https://lkml.org/lkml/2014/1/10/427 > >> > > >> > ... not sure, though. > >> > > >> > > >> >> [ 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 > >> > >> > >> > >> -- > >> Elena > > I was able to reproduce this consistently, also with the latest mm > patches from yesterday. > Can you please try this: > > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > index ce563be..76dcf96 100644 > --- a/arch/x86/xen/mmu.c > +++ b/arch/x86/xen/mmu.c > @@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct > *mm, unsigned long addr, > /* Assume pteval_t is equivalent to all the other *val_t types. */ > static pteval_t pte_mfn_to_pfn(pteval_t val) > { > - if (val & _PAGE_PRESENT) { > + if ((val & _PAGE_PRESENT) || ((val & > (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA)) { > unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; > unsigned long pfn = mfn_to_pfn(mfn); > > @@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val) > > static pteval_t pte_pfn_to_mfn(pteval_t val) > { > - if (val & _PAGE_PRESENT) { > + if ((val & _PAGE_PRESENT) || ((val & > (_PAGE_NUMA|_PAGE_PRESENT)) == _PAGE_NUMA)) { > unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT; > pteval_t flags = val & PTE_FLAGS_MASK; > unsigned long mfn; Thanks Elena, I just tested that and it does un-break things. - Steven -- 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/