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Message-ID: <CAEr7rXhJf1tf2KUErsGgUyYNUpVwLYD=fKUf8aPm0Dcg21MuNQ@mail.gmail.com> Date: Wed, 22 Jan 2014 15:18:50 -0500 From: Elena Ufimtseva <ufimtseva@...il.com> To: Daniel Borkmann <borkmann@...earbox.net> Cc: Steven Noonan <steven@...inklabs.net>, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com>, David Vrabel <david.vrabel@...rix.com>, xen-devel <xen-devel@...ts.xenproject.org>, George Dunlap <george.dunlap@...citrix.com>, Dario Faggioli <dario.faggioli@...rix.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Andrea Arcangeli <aarcange@...hat.com>, "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, Linux Kernel mailing List <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>, Alex Thorlton <athorlton@....com>, Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>, Michel Lespinasse <walken@...gle.com> Subject: Re: [BISECTED] Linux 3.12.7 introduces page map handling regression On Wed, Jan 22, 2014 at 9:29 AM, Daniel Borkmann <borkmann@...earbox.net> 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 >>>>> <gregkh@...uxfoundation.org> 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] [<ffffffff814d8748>] dump_stack+0x45/0x56 >>>> [ 368.756833] [<ffffffff8116d289>] print_bad_pte+0x229/0x250 >>>> [ 368.756837] [<ffffffff8116eae3>] >>>> unmap_single_vma+0x583/0x890 >>>> [ 368.756842] [<ffffffff8116feb5>] unmap_vmas+0x65/0x90 >>>> [ 368.756847] [<ffffffff81175dac>] unmap_region+0xac/0x120 >>>> [ 368.756852] [<ffffffff81176379>] ? vma_rb_erase+0x1c9/0x210 >>>> [ 368.756856] [<ffffffff81177f10>] do_munmap+0x280/0x370 >>>> [ 368.756860] [<ffffffff81178041>] vm_munmap+0x41/0x60 >>>> [ 368.756864] [<ffffffff81178f32>] SyS_munmap+0x22/0x30 >>>> [ 368.756869] [<ffffffff814e70ed>] >>>> 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: 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. > > > 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] [<ffffffff814d8768>] dump_stack+0x45/0x56 >> [ 346.374996] [<ffffffff8116d289>] print_bad_pte+0x229/0x250 >> [ 346.375000] [<ffffffff8116eae3>] unmap_single_vma+0x583/0x890 >> [ 346.375006] [<ffffffff8116feb5>] unmap_vmas+0x65/0x90 >> [ 346.375011] [<ffffffff81175dbc>] unmap_region+0xac/0x120 >> [ 346.375016] [<ffffffff81176389>] ? vma_rb_erase+0x1c9/0x210 >> [ 346.375021] [<ffffffff81177f20>] do_munmap+0x280/0x370 >> [ 346.375025] [<ffffffff81178051>] vm_munmap+0x41/0x60 >> [ 346.375029] [<ffffffff81178f42>] SyS_munmap+0x22/0x30 >> [ 346.375034] [<ffffffff814e712d>] >> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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