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From: Andrew Morton <akpm@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>,
	steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
	linux-kernel@vger.kernel.org, tglx@linutronix.de,
	mhocko@suse.com, linux-mm@kvack.org, mgorman@techsingularity.net,
	mingo@kernel.org, peterz@infradead.org, fengguang.wu@intel.com,
	dennisszhou@gmail.com
Subject: Re: [PATCH v2] mm: access to uninitialized struct page
Date: Mon, 30 Apr 2018 17:01:45 -0700	[thread overview]
Message-ID: <20180430170145.544342905604331c0e1b95d9@linux-foundation.org> (raw)
In-Reply-To: <20180430195858.5242373c@gandalf.local.home>

On Mon, 30 Apr 2018 19:58:58 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 30 Apr 2018 16:26:58 -0700
> Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > On Thu, 26 Apr 2018 16:26:19 -0400 Pavel Tatashin <pasha.tatashin@oracle.com> wrote:
> > 
> > > The following two bugs were reported by Fengguang Wu:
> > > 
> > > kernel reboot-without-warning in early-boot stage, last printk:
> > > early console in setup code
> > > 
> > > http://lkml.kernel.org/r/20180418135300.inazvpxjxowogyge@wfg-t540p.sh.intel.com
> > > 
> > > ...
> > >
> > > --- a/init/main.c
> > > +++ b/init/main.c
> > > @@ -585,8 +585,8 @@ asmlinkage __visible void __init start_kernel(void)
> > >  	setup_log_buf(0);
> > >  	vfs_caches_init_early();
> > >  	sort_main_extable();
> > > -	trap_init();
> > >  	mm_init();
> > > +	trap_init();
> > >  
> > >  	ftrace_init();  
> > 
> > Gulp.  Let's hope that nothing in mm_init() requires that trap_init()
> > has been run.  What happens if something goes wrong during mm_init()
> > and the architecture attempts to raise a software exception, hits a bus
> > error, div-by-zero, etc, etc?  Might there be hard-to-discover
> > dependencies in such a case?
> 
> I mentioned the same thing.
> 

I guess the same concern applies to all the code which we've always run
before trap_init(), and that's quite a lot of stuff.  So we should be
OK.  But don't quote me ;)

  reply	other threads:[~2018-05-01  0:01 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-26 20:26 Pavel Tatashin
2018-04-30 23:26 ` Andrew Morton
2018-04-30 23:58   ` Steven Rostedt
2018-05-01  0:01     ` Andrew Morton [this message]
2018-05-08 14:44   ` Pavel Tatashin
2018-05-04  8:27 ` [v2] " Andrei Vagin
2018-05-04 12:47   ` Pavel Tatashin
2018-05-04 14:50     ` Steven Rostedt
2018-05-04 16:01     ` Andrei Vagin
2018-05-04 16:03       ` Pavel Tatashin
2018-05-04 17:49         ` Andy Shevchenko
2018-05-05  1:04           ` Fengguang Wu

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