On 1/29/21 7:04 PM, Yang Shi wrote: >> > > @@ -209,9 +214,15 @@ static int expand_one_shrinker_info(struct >> > > mem_cgroup *memcg, >> > > if (!new) >> > > return -ENOMEM; >> > > >> > > - /* Set all old bits, clear all new bits */ >> > > - memset(new->map, (int)0xff, old_size); >> > > - memset((void *)new->map + old_size, 0, size - old_size); >> > > + new->map = (unsigned long *)(new + 1); >> > > + new->nr_deferred = (void *)new->map + m_size; >> > >> > This better be aligned to sizeof(atomic_long_t). Can we be sure about that? >> >> Good point. No, if unsigned long is 32 bit on some 64 bit machines. > > I think we could just change map to "u64" and guarantee struct > shrinker_info is aligned to 64 bit.
What about changing to order, nr_deferred before map? Then the atomics are at the beginning of allocated area, thus aligned.
