On Fri, Nov 3, 2017 at 4:21 AM, Jan Kara <jack@xxxxxxx> wrote:
> _calc_vm_trans() does not handle the situation when some of the passed
> flags are 0 (which can happen if these VM flags do not make sense for
> the architecture). Improve the _calc_vm_trans() macro to return 0 in
> such situation. Since all passed flags are constant, this does not add
> any runtime overhead.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> include/linux/mman.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> Dan, can you please prepend this patch before my series so that we don't
> break bisectability? This fixes the reported problem for me when arch
> does not define MAP_SYNC. Thanks!
>
> diff --git a/include/linux/mman.h b/include/linux/mman.h
> index 8f7cc87828e6..3427bf3daef5 100644
> --- a/include/linux/mman.h
> +++ b/include/linux/mman.h
> @@ -105,8 +105,9 @@ static inline bool arch_validate_prot(unsigned long prot)
> * ("bit1" and "bit2" must be single bits)
> */
> #define _calc_vm_trans(x, bit1, bit2) \
> + ((!(bit1) || !(bit2)) ? 0 : \
> ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
> - : ((x) & (bit1)) / ((bit1) / (bit2)))
> + : ((x) & (bit1)) / ((bit1) / (bit2))))
>
Looks good to me, thanks Jan.
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