Subject: Re: 2.6.26.6-rt11: BUGs (sleeping function called from invalid
	context)
From: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>, LKML <linux-kernel@vger.kernel.org>,
       Ingo Molnar <mingo@elte.hu>
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Date: Sat, 08 Nov 2008 10:28:23 -0800
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On Sat, 2008-11-08 at 09:47 +0100, Peter Zijlstra wrote:
> On Fri, 2008-11-07 at 15:52 -0800, Fernando Lopez-Lezcano wrote:
> > On Fri, 2008-11-07 at 22:47 +0100, Peter Zijlstra wrote:
> > > On Fri, 2008-11-07 at 13:35 -0800, Fernando Lopez-Lezcano wrote:
> > > > On Fri, 2008-11-07 at 20:16 +0100, Peter Zijlstra wrote:
> > > > > On Fri, 2008-11-07 at 14:01 -0500, Steven Rostedt wrote:
> > > > > > Peter, I think we've seen this before. It is the highmem code sleeping.
> > > > > 
> > > > > I've been working on an alternative kmap_atomic implementation for -rt,
> > > > > the below has been build and booted but not stressed, anybody care to
> > > > > give it a spin ?
> > > > 
> > > > I'll give it a try. Anything in particular I should try to do? Or not
> > > > do? Or watch for?
> > > 
> > > Lots of I/O should stress the i386 highmem stuff. If all is well it
> > > works, if not, crashes and splats.
> > 
> > Crashes and splats on boot... sorry, I don't have a way to capture the
> > kernel oops (or whatever happens, I can only see the end of the
> > printout)
> > 
> > ? speedstep_detect_processor
> > ? __copy_from_user_ll_noccache_nozero
> > iov_iter_copy_from_user_atomic
> > ? generic_file_buffered_write
> > generic_file_buffered_write
> > ? avs_has_perm_noaudit
> > ? __rt_spin_lock
> > ? selinux_inode_need_killpriv
> > ? __rt_spin_lock
> > mnt_drop_write
> > __generic_file_aio_write_nolock
> > generic_file_aio_write
> > do_sync_write
> > ? __enqueue_entity
> > ? autoremove_wake_function
> > ? selinux_file_oermission
> > ? security_file_permission
> > ? do_sync_write
> > vfs_write
> > sys_write
> > ? schedule_tail
> > ? ret_from_fork
> > ? thread_kernel_helper
> 
> Oh well, thanks for trying, I guess I need to go run this on real
> hardware, which means finding where I left this i386 distro on the test
> boxen :-)

Let me know if you have something to test (or just maybe a simpler fix
for the BUGs that I posted at the beginning of the thread?)

-- Fernando


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