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From: Shakeel Butt To: "T.J. Mercier" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/7] memcg: reduce memory for the lruvec and memcg stats Message-ID: References: <20240427003733.3898961-1-shakeel.butt@linux.dev> <20240427003733.3898961-4-shakeel.butt@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 66FF24000A X-Stat-Signature: 44c1n96zc4ci6tcorboiphm79f1pfmu6 X-Rspam-User: X-HE-Tag: 1714421593-377687 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000021, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 29, 2024 at 10:35:38AM -0700, T.J. Mercier wrote: > On Fri, Apr 26, 2024 at 5:37 PM Shakeel Butt wrote: > > [...] > > + > > +static const unsigned int memcg_stat_items[] = { > > + MEMCG_SWAP, > > + MEMCG_SOCK, > > + MEMCG_PERCPU_B, > > + MEMCG_VMALLOC, > > + MEMCG_KMEM, > > + MEMCG_ZSWAP_B, > > + MEMCG_ZSWAPPED, > > +}; > > Unsigned for these? All the values are positive now, but I don't think > we'll get a build warning if a negative one ever got added, just a > crash or corruption. BUG_ON in init_memcg_stats if a > memcg_stat_items[i] < 0? We are depending on NR_VM_NODE_STAT_ITEMS to tell the number of elements for vmstats. So, I think there is an implicit assumption that there are no negative enums in enum node_stat_item. So, if we want to verify those assumptions then we should be adding such warnings/build-bugs in vmstat first.