Re: [RFC PATCH v2 04/47] hugetlb: only adjust address ranges when VMAs want PMD sharing

[Mike Kravetz]

On 10/21/22 16:36, James Houghton wrote:
> Currently this check is overly aggressive. For some userfaultfd VMAs,
> VMA sharing is disabled, yet we still widen the address range, which is
> used for flushing TLBs and sending MMU notifiers.

Yes, the userfaultfd check is missing in the code today.

> This is done now, as HGM VMAs also have sharing disabled, yet would
> still have flush ranges adjusted. Overaggressively flushing TLBs and
> triggering MMU notifiers is particularly harmful with lots of
> high-granularity operations.
> 
> Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
> ---
>  mm/hugetlb.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)

Thanks,

Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
-- 
Mike Kravetz