Messages in this thread | | | Subject | Re: [PATCH] mm: Optimize put_mems_allowed() usage | From | Peter Zijlstra <> | Date | Thu, 17 May 2012 22:23:24 +0200 |
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On Thu, 2012-05-17 at 13:16 -0700, Andrew Morton wrote: > I do think it was a bad idea to remove that comment. As it stands, the > reader will be wondering why we did the read_mems_allowed_begin() at > all, and whether failing to check for a change is a bug. > > --- a/mm/slub.c~mm-optimize-put_mems_allowed-usage-fix > +++ a/mm/slub.c > @@ -1624,8 +1624,16 @@ static struct page *get_any_partial(stru > if (n && cpuset_zone_allowed_hardwall(zone, flags) && > n->nr_partial > s->min_partial) { > object = get_partial_node(s, n, c); > - if (object) > + if (object) { > + /* > + * Don't check read_mems_allowed_retry() > + * here - if mems_allowed was updated in > + * parallel, that was a harmless race > + * between allocation and the cpuset > + * update > + */ > return object; > + } > } > } > } while (read_mems_allowed_retry(cpuset_mems_cookie));
OK, it seemed weird to have that comment in this one place whilst it is the general pattern of this construct.
The whole read_mems_allowed_retry() should only ever be attempted in case the allocation failed.
But sure..
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