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dkim=pass header.d=gmail.com header.s=20210112 header.b=KGbJ7BAR; spf=pass (imf23.hostedemail.com: domain of laoar.shao@gmail.com designates 209.85.217.42 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1660186190-502739 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Aug 11, 2022 at 1:07 AM Shakeel Butt wrote: > > On Wed, Aug 10, 2022 at 03:18:30PM +0000, Yafang Shao wrote: > > The memcg may be the root_mem_cgroup, in which case we shouldn't put it. > > No, it is ok to put root_mem_cgroup. css_put already handles the root > cgroups. > Ah, this commit log doesn't describe the issue clearly. I should improve it. The issue is that in bpf_map_get_memcg() it doesn't get the objcg if map->objcg is NULL (that can happen if the map belongs to the root memcg), so we shouldn't put the objcg if map->objcg is NULL neither in bpf_map_put_memcg(). Maybe the change below would be more reasonable ? +static void bpf_map_put_memcg(const struct bpf_map *map, struct mem_cgroup *memcg) +{ + if (map->objcg) + mem_cgroup_put(memcg); +} -- Regards Yafang