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From: Shakeel Butt To: Roman Gushchin Cc: bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, JP Kobryn , Alexei Starovoitov , Daniel Borkmann , Michal Hocko , Johannes Weiner Subject: Re: [PATCH bpf-next v1 6/6] bpf: selftests: selftests for memcg stat kfuncs Message-ID: <2xhmcrporen72rskghn6hmg6obnojptuerwzqgu7mqzhnxaxs5@33dxlwa6rqlh> References: <20251219015750.23732-1-roman.gushchin@linux.dev> <20251219015750.23732-7-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251219015750.23732-7-roman.gushchin@linux.dev> X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 63q67dghizzjzkjjaw7ewj1zau8s4jxa X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E39FE12000A X-Rspam-User: X-HE-Tag: 1766185648-994136 X-HE-Meta: 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 C2so/VWs MfkamdIBLEcrsy/9+mkwEGjIwGnmeoXDaE9TWWn2naA4lYmdlNX7cLC+wXlSr87OvE2VMziL6TCatWwFUGWkT3NJlGwvgvsvzRWINLUbNNxZIOVp+jou+YWb8qsrs95ucldRpDuTKUajt4mF1HwcltWMnm+IUdldK6crE2gPuVbGYW4/5hAZ+NZjFGWoUOiWkcdpPeOHXyZ0K5p99AddONejWRqSCeGIWwDAZaHReb2oDdM6yeDpZePb3TcGE5Zx42yIHdpYotZdhuhQ= 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: List-Subscribe: List-Unsubscribe: On Thu, Dec 18, 2025 at 05:57:50PM -0800, Roman Gushchin wrote: > From: JP Kobryn > > Add test coverage for the kfuncs that fetch memcg stats. Using some common > stats, test scenarios ensuring that the given stat increases by some > arbitrary amount. The stats selected cover the three categories represented > by the enums: node_stat_item, memcg_stat_item, vm_event_item. > > Since only a subset of all stats are queried, use a static struct made up > of fields for each stat. Write to the struct with the fetched values when > the bpf program is invoked and read the fields in the user mode program for > verification. > > Signed-off-by: JP Kobryn Need your signoff [...] > + > +#define NR_PIPES 64 > +static void test_kmem(struct bpf_link *link, struct memcg_query *memcg_query) > +{ > + int fds[NR_PIPES][2], i; > + > + /* > + * Increase kmem value by creating pipes which will allocate some > + * kernel buffers. > + */ > + for (i = 0; i < NR_PIPES; i++) { > + if (!ASSERT_OK(pipe(fds[i]), "pipe")) > + goto cleanup; > + } > + > + if (!ASSERT_OK(read_stats(link), "read stats")) > + goto cleanup; > + > + ASSERT_GT(memcg_query->memcg_kmem, 0, "kmem value"); > + > +cleanup: > + for (i = 0; i < NR_PIPES; i++) { Instead of from 0 to NR_PIPES, we need to go from i-1 to (and equal to) 0 otherwise we can potentially close() junk values. > + close(fds[i][0]); > + close(fds[i][1]); > + } > +} > + [...] > + > +SEC("iter.s/cgroup") > +int cgroup_memcg_query(struct bpf_iter__cgroup *ctx) > +{ > + struct cgroup *cgrp = ctx->cgroup; > + struct cgroup_subsys_state *css; > + struct mem_cgroup *memcg; > + > + if (!cgrp) > + return 1; > + > + css = &cgrp->self; > + if (!css) Will css ever be NULL here? > + return 1; > + > + memcg = bpf_get_mem_cgroup(css); > + if (!memcg) > + return 1; > + > + bpf_mem_cgroup_flush_stats(memcg); > + > + memcg_query.nr_anon_mapped = bpf_mem_cgroup_page_state(memcg, NR_ANON_MAPPED); > + memcg_query.nr_shmem = bpf_mem_cgroup_page_state(memcg, NR_SHMEM); > + memcg_query.nr_file_pages = bpf_mem_cgroup_page_state(memcg, NR_FILE_PAGES); > + memcg_query.nr_file_mapped = bpf_mem_cgroup_page_state(memcg, NR_FILE_MAPPED); > + memcg_query.memcg_kmem = bpf_mem_cgroup_page_state(memcg, MEMCG_KMEM); > + memcg_query.pgfault = bpf_mem_cgroup_vm_events(memcg, PGFAULT); > + > + bpf_put_mem_cgroup(memcg); > + > + return 0; > +} > -- > 2.52.0 >