On Thu, Nov 01, 2018 at 04:30:12PM -0700, Joe Perches wrote: > On Thu, 2018-11-01 at 14:47 -0700, Andrew Morton wrote: > > +++ a/mm/page_owner.c > > @@ -351,7 +351,7 @@ print_page_owner(char __user *buf, size_ > > .skip = 0 > > }; > > > > - count = count > PAGE_SIZE ? PAGE_SIZE : count; > > + count = min_t(size_t, count, PAGE_SIZE); > > kbuf = kmalloc(count, GFP_KERNEL); > > if (!kbuf) > > return -ENOMEM; > > A bit tidier still might be > > if (count > PAGE_SIZE) > count = PAGE_SIZE; > > as that would not always cause a write back to count.
90% chance 'count' is already in a register and will stay there. 99.9% chance that if it's not in a register, it's on the top of the stack, which is by definition a hot, local, dirty cacheline. What you're saying makes sense for a struct which might well be in a shared cacheline state. But for a function-local variable? No.
