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From: "Jan Beulich" <JBeulich@suse.com>
To: "Matt Fleming" <matt.fleming@intel.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Markus Trippelsdorf" <markus@trippelsdorf.de>
Cc: "Arnd Bergmann" <arnd@arndb.de>, "Ingo Molnar" <mingo@elte.hu>,
	"Michael Kerrisk" <mtk.manpages@gmail.com>,
	"Guennadi Liakhovetski" <g.liakhovetski@gmx.de>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	"Dave Jones" <davej@redhat.com>,
	"David Howells" <dhowells@redhat.com>,
	"Grant Likely" <grant.likely@secretlab.ca>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Re: [GIT PULL] x86/uapi for 3.8
Date: Mon, 17 Dec 2012 09:04:35 +0000	[thread overview]
Message-ID: <50CEEE3302000078000B0AC0@nat28.tlf.novell.com> (raw)
In-Reply-To: <CA+55aFz3iLPT3wzbU_Nhh4ft1eNQcd4WdQXsgXnKBs6vG9a_Uw@mail.gmail.com>

>>> On 15.12.12 at 19:35, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Sat, Dec 15, 2012 at 8:33 AM, Markus Trippelsdorf
> <markus@trippelsdorf.de> wrote:
>> On 2012.12.14 at 17:47 -0800, Linus Torvalds wrote:
>>>
>>> Ho humm. Anybody else see anything strange?
>>
>> Yes. I'm seeing a BUG early during boot on my machine (RIP=NULL):
>>
>>  BUG: unable to handle kernel NULL pointer dereference at           (null)
>>
>> This is caused by commit 53b87cf088e2 ("x86, mm: Include the
>> entire kernel memory map in trampoline_pgd")
> 
> Hmm. That reverts cleanly, and the result boots fine for me. And the
> commit looks like exactly the kind of thing that could result in
> problems with exactly the right memory layout, so it could explain why
> the bisect failed and some kernels randomly worked for me and others
> didn't.
> 
> So this at least looks like a very possible candidate.
> 
> Does anybody have an explanation for the problem?

How about this being caused by using the same lower level
page table entries that swapper_pg_dir uses, namely including
the _PAGE_GLOBAL bits? efi_call_virt_{pre,epi}log() only write
CR3 (see 185034e72d591f9465e5e18f937ed642e7ea0070), but
would need to also flip CR4.PGE afaict.

Jan


  parent reply	other threads:[~2012-12-17  9:04 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-12 22:11 [GIT PULL] x86/uapi for 3.8 H. Peter Anvin
2012-12-12 23:48 ` David Howells
2012-12-14 18:25   ` Linus Torvalds
2012-12-14 23:45   ` David Howells
2012-12-15  1:16     ` Linus Torvalds
2012-12-15  1:41       ` Linus Torvalds
2012-12-15  1:47         ` Linus Torvalds
2012-12-15 16:33           ` Markus Trippelsdorf
2012-12-15 16:35             ` Markus Trippelsdorf
2012-12-16 12:43               ` Matt Fleming
2012-12-16 13:25                 ` Markus Trippelsdorf
2012-12-16 14:54                   ` Matt Fleming
2012-12-16 20:12                     ` Linus Torvalds
2012-12-16 22:07                       ` Linus Torvalds
2012-12-16 22:25                         ` H. Peter Anvin
2012-12-16 22:40                         ` Matt Fleming
2012-12-16 22:52                           ` Linus Torvalds
2012-12-16 23:49                         ` Markus Trippelsdorf
2012-12-15 18:35             ` Linus Torvalds
2012-12-15 19:41               ` H. Peter Anvin
2012-12-15 19:58                 ` Linus Torvalds
2012-12-15 20:06                   ` Markus Trippelsdorf
2012-12-15 21:04                   ` Markus Trippelsdorf
2012-12-15 21:06                     ` Linus Torvalds
2012-12-15 21:36                       ` H. Peter Anvin
2012-12-15 22:05                       ` Yinghai Lu
2012-12-15 23:37                         ` Linus Torvalds
2012-12-15 23:46                           ` H. Peter Anvin
2012-12-16 12:46                           ` Matt Fleming
2012-12-15 21:37                   ` Dave Jones
2012-12-15 23:47                     ` H. Peter Anvin
2012-12-17  9:04               ` Jan Beulich [this message]
2012-12-17 15:44                 ` Linus Torvalds
2012-12-17 16:00                   ` Jan Beulich
2012-12-17 16:39                     ` H. Peter Anvin
2012-12-17 17:03                       ` Jan Beulich
2012-12-17 17:15                         ` H. Peter Anvin
2012-12-18  8:02                           ` Jan Beulich
2012-12-15  4:25       ` H. Peter Anvin

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