LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Luck, Tony" <tony.luck@intel.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	X86 ML <x86@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Darren Hart <dvhart@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-edac <linux-edac@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery
Date: Tue, 12 Jan 2021 17:50:53 -0800	[thread overview]
Message-ID: <20210113015053.GA21587@agluck-desk2.amr.corp.intel.com> (raw)
In-Reply-To: <38AF04BE-7F39-450F-8C26-879C9934E3D6@amacapital.net>

On Tue, Jan 12, 2021 at 02:04:55PM -0800, Andy Lutomirski wrote:
> > But we know that the fault happend in a get_user() or copy_from_user() call
> > (i.e. an RIP with an extable recovery address).  Does context switch
> > access user memory?
> 
> No, but NMI can.
> 
> The case that would be very very hard to deal with is if we get an NMI just before IRET/SYSRET and get #MC inside that NMI.
> 
> What we should probably do is have a percpu list of pending memory failure cleanups and just accept that we’re going to sometimes get a second MCE (or third or fourth) before we can get to it.
> 
> Can we do the cleanup from an interrupt?  IPI-to-self might be a credible approach, if so.

You seem to be looking for a solution that is entirely contained within
the machine check handling code. Willing to allow for repeated machine
checks from the same poison address in order to achieve that.

I'm opposed to mutliple machine checks.  Willing to make some changes
in core code to avoid repeated access to the same poison location.

We need a tie-breaker.

-Tony

  reply	other threads:[~2021-01-13  1:51 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-08 22:22 [PATCH 0/2] Fix infinite machine check loop in futex_wait_setup() Tony Luck
2021-01-08 22:22 ` [PATCH 1/2] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-08 22:22 ` [PATCH 2/2] futex, x86/mce: Avoid double machine checks Tony Luck
2021-01-08 22:47   ` Peter Zijlstra
2021-01-08 23:08     ` Luck, Tony
2021-01-08 23:14       ` Peter Zijlstra
2021-01-08 23:20         ` Luck, Tony
2021-01-11 21:44 ` [PATCH v2 0/3] Fix infinite machine check loop in futex_wait_setup() Tony Luck
2021-01-11 21:44   ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-11 22:11     ` Andy Lutomirski
2021-01-11 22:20       ` Luck, Tony
2021-01-12 17:00         ` Andy Lutomirski
2021-01-12 17:16           ` Luck, Tony
2021-01-12 17:21             ` Andy Lutomirski
2021-01-12 18:23               ` Luck, Tony
2021-01-12 18:57                 ` Andy Lutomirski
2021-01-12 20:52                   ` Luck, Tony
2021-01-12 22:04                     ` Andy Lutomirski
2021-01-13  1:50                       ` Luck, Tony [this message]
2021-01-13  4:15                         ` Andy Lutomirski
2021-01-13 10:00                           ` Borislav Petkov
2021-01-13 16:06                             ` Luck, Tony
2021-01-13 16:19                               ` Borislav Petkov
2021-01-13 16:32                                 ` Luck, Tony
2021-01-13 17:35                                   ` Borislav Petkov
2021-01-14 20:22     ` Borislav Petkov
2021-01-14 21:05       ` Luck, Tony
2021-01-11 21:44   ` [PATCH v2 2/3] x86/mce: Add new return value to get_user() for machine check Tony Luck
2021-01-11 21:44   ` [PATCH v2 3/3] futex, x86/mce: Avoid double machine checks Tony Luck
2021-01-14 17:22   ` [PATCH v2 0/3] Fix infinite machine check loop in futex_wait_setup() Andy Lutomirski
2021-01-15  0:38   ` [PATCH v3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-01-15 15:27     ` Borislav Petkov
2021-01-15 19:34       ` Luck, Tony
2021-01-15 20:51         ` [PATCH v4] " Luck, Tony
2021-01-15 23:23           ` Luck, Tony
2021-01-19 10:56             ` Borislav Petkov
2021-01-19 23:57               ` Luck, Tony
2021-01-20 12:18                 ` Borislav Petkov
2021-01-20 17:17                   ` Luck, Tony
2021-01-21 21:09                   ` Luck, Tony
2021-01-25 22:55                     ` [PATCH v5] " Luck, Tony
2021-01-26 11:03                       ` Borislav Petkov
2021-01-26 22:36                         ` Luck, Tony
2021-01-28 17:57                           ` Borislav Petkov
2021-02-01 18:58                             ` Luck, Tony
2021-02-02 11:01                               ` Borislav Petkov
2021-02-02 16:04                                 ` Luck, Tony
2021-02-02 21:06                                   ` Borislav Petkov
2021-02-02 22:12                                     ` Luck, Tony
2021-01-18 15:39         ` [PATCH v3] " Borislav Petkov
2021-07-06 19:06 [PATCH 0/3] More machine check recovery fixes Tony Luck
2021-08-18  0:29 ` [PATCH v2 " Tony Luck
2021-08-18  0:29   ` [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery Tony Luck
2021-08-20 17:31     ` Borislav Petkov
2021-08-20 18:59       ` Luck, Tony
2021-08-20 19:27         ` Borislav Petkov
2021-08-20 20:23           ` Luck, Tony
2021-08-21  4:51             ` Tony Luck
2021-08-21 21:51               ` Al Viro
2021-08-22 14:36             ` Borislav Petkov
2021-08-20 20:33           ` Luck, Tony
2021-08-22 14:46             ` Borislav Petkov
2021-08-23 15:24               ` Luck, Tony
2021-09-13  9:24     ` Borislav Petkov

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=20210113015053.GA21587@agluck-desk2.amr.corp.intel.com \
    --to=tony.luck@intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=bp@alien8.de \
    --cc=dvhart@infradead.org \
    --cc=linux-edac@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=luto@amacapital.net \
    --cc=luto@kernel.org \
    --cc=peterz@infradead.org \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery' \
    /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

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).