Re: [PATCH next] sysfs: fix some bin_vm_ops errors

[Benjamin Herrenschmidt]

On Sun, 2009-03-22 at 18:33 +0000, Hugh Dickins wrote:
> Commit 86c9508eb1c0ce5aa07b5cf1d36b60c54efc3d7a
> "sysfs: don't block indefinitely for unmapped files" in linux-next
> crashes the PowerMac G5 when X starts up.  It's caught out by the way
> powerpc's pci_mmap of legacy_mem uses shmem_zero_setup(), substituting
> a new vma->vm_file whose private_data no longer points to the bin_buffer
> (substitution done because some versions of X crash if that mmap fails).
> 
> The fix to this is straightforward: the original vm_file is fput() in
> that case, so this mmap won't block sysfs at all, so just don't switch
> over to bin_vm_ops if vm_file has changed.

Looks good, though we should probably also add a comment to your code
to make it clear why the test is here.

The fix should probably go into .29...

Cheers,
Ben.


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