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Tue, 28 Nov 2023 10:07:18 +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 zBOZNNa7ZWXyagAAD6G6ig (envelope-from ); Tue, 28 Nov 2023 10:07:18 +0000 Date: Tue, 28 Nov 2023 11:07:18 +0100 From: Michal Hocko To: Kent Overstreet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Qi Zheng , Roman Gushchin Subject: Re: [PATCH 4/7] mm: Centralize & improve oom reporting in show_mem.c Message-ID: References: <20231122232515.177833-1-kent.overstreet@linux.dev> <20231122232515.177833-5-kent.overstreet@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231122232515.177833-5-kent.overstreet@linux.dev> X-Spamd-Bar: +++++++++++++++ X-Spam: Yes X-Rspamd-Queue-Id: D8F581C001E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: zusz9nweaudk4cb9wm8s8pghpqb3ro1n X-HE-Tag: 1701166040-742397 X-HE-Meta: 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 kwE8Ip/X XH1g68JdTSOEaNbqpkZyiKxbckrtnxDJ2RlvzkgLdZkIIUdPJI82dL6QXWi+TA+BIvC8oSZc3bMGTsJzKctwTGdLOravvDfoM8SS/RB1BZp0zFtRFT9e0SDk++Usiu95dodQsu4y7SN+HY4IqC39LrnT9MVo9KNwGeR46Du6sbrRiEmGGQl67WX9X0odZwhoj3b8Xh9xvLaHstSYAQCYT84qFpg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 Wed 22-11-23 18:25:09, Kent Overstreet wrote: [...] > 00177 Shrinkers: > 00177 super_cache_scan: objects: 127 > 00177 super_cache_scan: objects: 106 > 00177 jbd2_journal_shrink_scan: objects: 32 > 00177 ext4_es_scan: objects: 32 > 00177 bch2_btree_cache_scan: objects: 8 > 00177 nr nodes: 24 > 00177 nr dirty: 0 > 00177 cannibalize lock: 0000000000000000 > 00177 > 00177 super_cache_scan: objects: 8 > 00177 super_cache_scan: objects: 1 It would be really great to provide an example on how these numbers are useful for the oom evaluation. [...] > @@ -423,4 +426,21 @@ 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 > + > + buf = kmalloc(4096, GFP_ATOMIC); I really do not think we want to allow allocations from the OOM context. Is there any reason why this cannot be a statically allocated buffer? > + if (buf) { > + struct seq_buf s; > + > + printk("Unreclaimable slab info:\n"); > + seq_buf_init(&s, buf, 4096); > + dump_unreclaimable_slab(&s); > + printk("%s", seq_buf_str(&s)); > + > + printk("Shrinkers:\n"); > + seq_buf_init(&s, buf, 4096); > + shrinkers_to_text(&s); > + printk("%s", seq_buf_str(&s)); > + > + kfree(buf); > + } > } -- Michal Hocko SUSE Labs