From: Borislav Petkov <bp@alien8.de>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>,
Prarit Bhargava <prarit@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Junichi Nomura <j-nomura@ce.jp.nec.com>,
Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Subject: Re: [PATCH v3 1/2] x86: mce: kexec: switch MCE handler for kexec/kdump
Date: Tue, 3 Mar 2015 19:53:24 +0100 [thread overview]
Message-ID: <20150303185324.GF25768@pd.tnic> (raw)
In-Reply-To: <1425373306-26187-1-git-send-email-n-horiguchi@ah.jp.nec.com>
On Tue, Mar 03, 2015 at 09:01:49AM +0000, Naoya Horiguchi wrote:
> kexec disables (or "shoots down") all CPUs other than a crashing CPU before
> entering the 2nd kernel. But the MCE handler is still enabled after that,
> so if MCE happens and broadcasts over the CPUs after the main thread starts
> the 2nd kernel (which might not initialize MCE device yet, or might decide
> not to enable it,) MCE handler runs only on the other CPUs (not on the main
> thread,) leading to kernel panic with MCE synchronization. The user-visible
> effect of this bug is kdump failure.
>
> Our standard MCE handler do_machine_check() assumes some about system's
> status and it's hard to alter it to cover kexec/kdump context, so let's add
> another kdump-specific one and switch to it.
>
> Note that this problem exists since current MCE handler was implemented in
> 2.6.32, and recently commit 716079f66eac ("mce: Panic when a core has reached
> a timeout") made it more visible by changing the default behavior of the
> synchronization timeout from "ignore" to "panic".
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: <stable@vger.kernel.org> [2.6.32+]
> ---
> ChangeLog v2 -> v3
> - go to "switch MCE handler" approach
>
> ChangeLog v1 -> v2
> - clear MSR_IA32_MCG_CTL, MSR_IA32_MCx_CTL, and CR4.MCE instead of using
> global flag to ignore MCE events.
> - fixed the description of the problem
> ---
> arch/x86/include/asm/mce.h | 6 +++++
> arch/x86/kernel/cpu/mcheck/mce.c | 47 ++++++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/crash.c | 3 +++
> 3 files changed, 56 insertions(+)
>
> diff --git v3.19.orig/arch/x86/include/asm/mce.h v3.19/arch/x86/include/asm/mce.h
> index 51b26e895933..8010d4b77183 100644
> --- v3.19.orig/arch/x86/include/asm/mce.h
> +++ v3.19/arch/x86/include/asm/mce.h
> @@ -114,6 +114,9 @@ struct mca_config {
> int monarch_timeout;
> int panic_timeout;
> u32 rip_msr;
> +#ifdef CONFIG_KEXEC
> + int kdump_cpu;
> +#endif
This CONFIG_KEXEC-ifdeffery is too ugly to live. Please put everything
in arch/x86/kernel/crash.c. AFAICT, you don't need to touch anything in
arch/x86/kernel/cpu/mcheck/ for your purposes.
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-03-03 18:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-03 9:01 [PATCH v3 1/2] x86: mce: kexec: switch MCE handler for kexec/kdump Naoya Horiguchi
2015-03-03 9:01 ` [PATCH v3 2/2] x86: mce: comment about MCE synchronization timeout on definition of tolerant Naoya Horiguchi
2015-03-03 18:09 ` [PATCH v3 1/2] x86: mce: kexec: switch MCE handler for kexec/kdump Luck, Tony
2015-03-04 7:41 ` [PATCH v4] " Naoya Horiguchi
2015-03-04 23:12 ` Luck, Tony
2015-03-05 1:24 ` Naoya Horiguchi
2015-03-05 6:45 ` [PATCH v5] " Naoya Horiguchi
2015-03-05 8:57 ` Borislav Petkov
2015-03-05 9:37 ` Naoya Horiguchi
2015-03-06 2:59 ` [PATCH v6] " Naoya Horiguchi
2015-03-06 8:34 ` Borislav Petkov
2015-03-06 9:09 ` Naoya Horiguchi
2015-03-06 9:27 ` Borislav Petkov
2015-03-06 9:32 ` Naoya Horiguchi
2015-03-06 10:22 ` [PATCH v7] " Naoya Horiguchi
2015-04-06 7:18 ` Naoya Horiguchi
2015-04-06 11:59 ` Borislav Petkov
2015-04-07 8:00 ` Naoya Horiguchi
2015-04-07 8:02 ` [PATCH v8] " Naoya Horiguchi
2015-04-09 6:13 ` Borislav Petkov
2015-04-09 6:57 ` Naoya Horiguchi
2015-04-09 7:02 ` Borislav Petkov
2015-04-09 18:07 ` Luck, Tony
2015-04-09 8:00 ` Ingo Molnar
2015-04-09 8:21 ` Borislav Petkov
2015-04-09 8:59 ` Naoya Horiguchi
2015-04-09 9:53 ` Borislav Petkov
2015-04-09 18:22 ` Luck, Tony
2015-04-09 19:05 ` Borislav Petkov
2015-04-10 0:49 ` Naoya Horiguchi
2015-04-10 4:07 ` Naoya Horiguchi
2015-04-10 7:24 ` Borislav Petkov
2015-04-28 8:41 ` Baoquan He
2015-04-09 8:39 ` Naoya Horiguchi
2015-04-09 9:13 ` Ingo Molnar
2015-04-06 11:56 ` [PATCH v7] " Borislav Petkov
2015-04-07 7:59 ` Naoya Horiguchi
2015-03-06 8:28 ` [PATCH v5] " Borislav Petkov
2015-03-06 5:44 ` [PATCH v4] " Naoya Horiguchi
2015-03-05 8:48 ` Borislav Petkov
2015-03-03 18:53 ` Borislav Petkov [this message]
2015-03-04 7:51 ` [PATCH v3 1/2] " Naoya Horiguchi
2015-03-04 9:12 ` Borislav Petkov
2015-03-05 1:27 ` Naoya Horiguchi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150303185324.GF25768@pd.tnic \
--to=bp@alien8.de \
--cc=j-nomura@ce.jp.nec.com \
--cc=k-ueda@ct.jp.nec.com \
--cc=linux-kernel@vger.kernel.org \
--cc=n-horiguchi@ah.jp.nec.com \
--cc=prarit@redhat.com \
--cc=tony.luck@intel.com \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).