On Fri, 26 Jul 2019 20:42:05 -0700 Nathan Chancellor <natechancel...@gmail.com> 
wrote:

> > @@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
> >      */
> >     clamped_high = max(high, 1UL);
> >  
> > -   overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
> > -           / clamped_high;
> > +   overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> > +   do_div(overage, clamped_high);
> > +
> >     penalty_jiffies = ((u64)overage * overage * HZ)
> >             >> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
> >  
> > _
> > 
> 
> This causes a build error on arm:
> 

Ah.

It's rather unclear why that u64 cast is there anyway.  We're dealing
with ulongs all over this code.  The below will suffice.

Chris, please take a look?

--- 
a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix-fix
+++ a/mm/memcontrol.c
@@ -2415,7 +2415,7 @@ void mem_cgroup_handle_over_high(void)
        clamped_high = max(high, 1UL);
 
        overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
-       do_div(overage, clamped_high);
+       overage /= clamped_high;
 
        penalty_jiffies = ((u64)overage * overage * HZ)
                >> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
_

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