Re: memory corruption, possibly caused by i915

[Dave Jones <davej@redhat.com>]

On Wed, Jan 02, 2013 at 11:01:15AM -0500, Chris Mason wrote:
 > > [52460.280346] BUG: Bad page map in process panel-6-systray  pte:ffff8800b665a0e8 pmd:b6659067
 > > [52460.280848] addr:00000038bf3fd000 vm_flags:00000070 anon_vma:          (null) mapping:ffff88011052fd98 index:1fd
 > > [52460.281547] vma->vm_ops->fault: filemap_fault+0x0/0x470
 > > [52460.281878] vma->vm_file->f_op->mmap: btrfs_file_mmap+0x0/0x60 [btrfs]
 > > 
 > > It's falling over in btrfs's mmap op, but I think it's just the victim here,
 > > of something else corrupting what had been mmaped in the panel process.
 > 
 > It's a btrfs file, but this isn't in our mmap op.  The traces are
 > finding bad pages at unmap time. 

Sorry, bad wording on my part.
 
 > > Daniel, can you think of additional sanity checks that could be added to
 > > the i915 driver ? (Even if at the expense of speed: a CONFIG_DEBUG option
 > > to prove correctness would be very worthwhile imo)
 > 
 > If the bad pages are getting all the way to btrfs,
 > CONFIG_DEBUG_PAGE_ALOC may help?  You've got lockdep on so maybe you
 > already enabled it.

Yeah, already enabled.

Thanks.

	Dave.