Messages in this thread | | | From | Muchun Song <> | Date | Sat, 13 Nov 2021 10:44:41 +0800 | Subject | Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file |
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On Sat, Nov 13, 2021 at 7:36 AM Mike Kravetz <mike.kravetz@oracle.com> wrote: > > Subject: Re: [PATCH v6] hugetlb: Add hugetlb.*.numa_stat file > > To: Muchun Song <songmuchun@bytedance.com>, Mina Almasry <almasrymina@google.com> > > Cc: Andrew Morton <akpm@linux-foundation.org>, Shuah Khan <shuah@kernel.org>, Miaohe Lin <linmiaohe@huawei.com>, Oscar Salvador <osalvador@suse.de>, Michal Hocko <mhocko@suse.com>, David Rientjes <rientjes@google.com>, Shakeel Butt <shakeelb@google.com>, Jue Wang <juew@google.com>, Yang Yao <ygyao@google.com>, Joanna Li <joannali@google.com>, Cannon Matthews <cannonmatthews@google.com>, Linux Memory Management List <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org> > > Bcc: > > -=-=-=-=-=-=-=-=-=# Don't remove this line #=-=-=-=-=-=-=-=-=- > > On 11/10/21 6:36 PM, Muchun Song wrote: > > > On Thu, Nov 11, 2021 at 9:50 AM Mina Almasry <almasrymina@google.com> wrote: > > >> > > >> +struct hugetlb_cgroup_per_node { > > >> + /* hugetlb usage in pages over all hstates. */ > > >> + atomic_long_t usage[HUGE_MAX_HSTATE]; > > > > > > Why do you use atomic? IIUC, 'usage' is always > > > increased/decreased under hugetlb_lock except > > > hugetlb_cgroup_read_numa_stat() which is always > > > reading it. So I think WRITE_ONCE/READ_ONCE > > > is enough. > > > > Thanks for continuing to work this, I was traveling and unable to > > comment.
Have a good time.
> > > > Unless I am missing something, I do not see a reason for WRITE_ONCE/READ_ONCE
Because __hugetlb_cgroup_commit_charge and hugetlb_cgroup_read_numa_stat can run parallely, which meets the definition of data race. I believe KCSAN could report this race. I'm not strongly suggest using WRITE/READ_ONCE() here. But in theory it should be like this. Right?
Thanks.
> > and would suggest going back to the way this code was in v5. > > -- > > Mike Kravetz >
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