Messages in this thread Patch in this message | | | Date | Wed, 17 Nov 2021 16:12:49 -0800 | Subject | Re: [PATCH v7] hugetlb: Add hugetlb.*.numa_stat file | From | Mike Kravetz <> |
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On 11/17/21 12:18, Mina Almasry wrote: ... > diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c ... > @@ -288,11 +317,21 @@ static void __hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages, > struct hugetlb_cgroup *h_cg, > struct page *page, bool rsvd) > { > + unsigned long *usage; > +
I assume the use of a pointer is just to make the following WRITE_ONCE look better? I prefer the suggestion by Muchun:
unsigned long usage = h_cg->nodeinfo[page_to_nid(page)]->usage[idx];
usage += nr_pages; WRITE_ONCE(h_cg->nodeinfo[page_to_nid(page)]->usage[idx], usage);
I had to think for just a second 'why are we using/passing a pointer?'. Not insisting we use Muchun's suggestion, it just caused me to think a little more than necessary.
In any case, I would move the variable usage inside the 'if (!rsvd)' block.
> if (hugetlb_cgroup_disabled() || !h_cg) > return; > > __set_hugetlb_cgroup(page, h_cg, rsvd); > - return; > + if (!rsvd) { > + usage = &h_cg->nodeinfo[page_to_nid(page)]->usage[idx]; > + /* > + * This write is not atomic due to fetching *usage and writing > + * to it, but that's fine because we call this with > + * hugetlb_lock held anyway. > + */ > + WRITE_ONCE(*usage, *usage + nr_pages); > + } > } > > void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages, > @@ -316,6 +355,7 @@ static void __hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages, > struct page *page, bool rsvd) > { > struct hugetlb_cgroup *h_cg; > + unsigned long *usage;
Same here.
Otherwise, looks good to me. -- Mike Kravetz
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