linux-kernel - RE: Re: [V2 PATCH 1/3] x86/panic: Fix re-entrance problem due to panic on NMI

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Date:	Tue, 4 Aug 2015 11:53:28 +0000
From:	河合英宏 / KAWAI，HIDEHIRO 
	<hidehiro.kawai.ez@...achi.com>
To:	"'Michal Hocko'" <mhocko@...nel.org>
CC:	Jonathan Corbet <corbet@....net>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vivek Goyal <vgoyal@...hat.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>,
	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
Subject: RE: Re: [V2 PATCH 1/3] x86/panic: Fix re-entrance problem due to
 panic on NMI

Hi,

> From: Michal Hocko [mailto:mhocko@...nel.org]
> On Fri 31-07-15 11:23:00, 河合英宏 / KAWAI，HIDEHIRO wrote:
> > > From: Michal Hocko [mailto:mhocko@...nel.org]
> > > > There is a timeout of 1000ms in nmi_shootdown_cpus(), so I don't know
> > > > why CPU 130 waits so long.  I'll try to consider for a while.
> > >
> > > Yes, I do not understand the timing here either and the fact that the
> > > log is a complete mess in the important parts doesn't help a wee bit.
> >
> > I'm interested in where "kernel panic -not syncing: " is.
> > It may give us a clue.
> 
> This one is lost in the mangled text:
> [  167.843771] U<0>[  167.843771] hhuh. NMI received for unkn<0><0>[  167.843765] Uh[  16NM843774I own rea reived for
> unknow<0 r  16n 2d 765] Uhhuh. CPU recei11. <0known reason 7. on770] Ker<[ - not rn NMI:nic - not contt sing
> 
> <0 >[ : Not con.inu437azed and confused, b] Dtryingaed annue
> 
> fu 167.8ut trying>[   to 7.<0377 167.843775] U<0>[  167.843776] ]hhu.ived for u3nknown rMason 3 re oived for [nk167.843781]

Thanks for the information.

I anticipated that some lock contention on issuing messages (e.g.
locks used by network/netconsole driver) delayed the panic procedure,
but it seems not to be related because the panic message finished to
be issued early.

If I come up with something, I will post a mail.  I think there
may be potential issues.

> 1.
> <. N0>[  167.843781] Uh. NMI recen 3d on CPU 0.i< >[ nowon 3d on] Chhuh.MI
> eceived[ or7.843nknoUhhuh.wn rMason e3d ceCPivUd 120.
> <0nk>no 167.wn843ason 3na s p120.
> o<0er savi d6 e843ab88] Do yeu have a
> <trange0>[ er saving mode e nabl1d?7<4][  167 84hu94]MIuh. NceIived for unknown reas vdfor 1no3was0>[ 2d 67.84380on CI
> rUe 12e.
> ive7d8u3800wn rveaseo f2d on CPo3.r< u>k[o 1 rea6s.o2d8 oo you hn aPve <0st>a e power 1s7.843816] Do yoauv ng moade
> enbslra?ng[ e 167.8438p41o]er shhuhavi.ngIroenived fbled?nknow
> < reaso0> 2d on [PU1626.41]0>   Uh67.h. NM387I] receihed for .nknown reason  2Nn MC U ceived for .
> [son 2d on CPU 6.
> <  160>7.8467.84873] Uhhuh. 3MI received 908 o knstra
> [ n167.843908] Do ygo pave westrangesa pvnv mode enableng mode ed?
> n<b0ed?

Regards,
Kawai