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Thu, 15 Feb 2024 16:45:01 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 8HpaEo0/zmW6CQAAD6G6ig (envelope-from ); Thu, 15 Feb 2024 16:45:01 +0000 Date: Thu, 15 Feb 2024 17:44:59 +0100 From: Michal Hocko To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem() Message-ID: References: <20240212213922.783301-1-surenb@google.com> <20240212213922.783301-32-surenb@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; 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FREEMAIL_CC(0.00)[linux-foundation.org,linux.dev,suse.cz,cmpxchg.org,suse.de,stgolabs.net,infradead.org,oracle.com,lwn.net,manifault.com,redhat.com,arm.com,kernel.org,arndb.de,linutronix.de,linux.intel.com,kernel.dk,soleen.com,google.com,gmail.com,chromium.org,linuxfoundation.org,linaro.org,goodmis.org,linux.com,lge.com,bytedance.com,akamai.com,android.com,vger.kernel.org,lists.linux.dev,kvack.org,googlegroups.com]; RCVD_TLS_ALL(0.00)[]; SUSPICIOUS_RECIPS(1.50)[] X-Spam-Score: -1.51 X-Rspamd-Queue-Id: 7DEFE1F8BF X-Spam-Flag: NO On Thu 15-02-24 06:58:42, Suren Baghdasaryan wrote: > On Thu, Feb 15, 2024 at 1:22 AM Michal Hocko wrote: > > > > On Mon 12-02-24 13:39:17, Suren Baghdasaryan wrote: > > [...] > > > @@ -423,4 +424,18 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx) > > > #ifdef CONFIG_MEMORY_FAILURE > > > printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages)); > > > #endif > > > +#ifdef CONFIG_MEM_ALLOC_PROFILING > > > + { > > > + struct seq_buf s; > > > + char *buf = kmalloc(4096, GFP_ATOMIC); > > > + > > > + if (buf) { > > > + printk("Memory allocations:\n"); > > > + seq_buf_init(&s, buf, 4096); > > > + alloc_tags_show_mem_report(&s); > > > + printk("%s", buf); > > > + kfree(buf); > > > + } > > > + } > > > +#endif > > > > I am pretty sure I have already objected to this. Memory allocations in > > the oom path are simply no go unless there is absolutely no other way > > around that. In this case the buffer could be preallocated. > > Good point. We will change this to a smaller buffer allocated on the > stack and will print records one-by-one. Thanks! __show_mem could be called with a very deep call chains. A single pre-allocated buffer should just do ok. -- Michal Hocko SUSE Labs