Re: [PATCH v1] s390x/mm: cleanup gmap_pte_op_walk()

[Janosch Frank <frankja@linux.vnet.ibm.com>]

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This is KVM, not qemu, subject s/x//


On 10.11.2017 16:18, David Hildenbrand wrote:
> gmap_mprotect_notify() refuses shadow gmaps. Turns out that
> a) gmap_protect_range()
> b) gmap_read_table()
> c) gmap_pte_op_walk()
> 
> Are never called for gmap shadows. And never should be. This dates back
> to gmap shadow prototypes where we allowed to call mprotect_notify() on
> the gmap shadow (to get notified about the prefix pages getting removed).
> This is avoided by always getting notified about any change on the gmap
> shadow.
> 
> The only real function for walking page tables on shadow gmaps is
> gmap_table_walk().
> 
> So, essentially, these functions should never get called and
> gmap_pte_op_walk() can be cleaned up. Add some checks to callers of
> gmap_pte_op_walk().

This already made sense when discussing, but I traced the callers anyhow
to make sure we didn't accidentally forget one.

Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com> with one nit below

> @@ -889,7 +879,6 @@ static void gmap_pte_op_end(spinlock_t *ptl)
>   *
>   * Called with sg->mm->mmap_sem in read.
>   *
> - * Note: Can also be called for shadow gmaps.

How about also getting rid of the line above this one?


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