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Thu, 15 Feb 2024 11:10:38 +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 X+24NS7xzWX4NAAAD6G6ig (envelope-from ); Thu, 15 Feb 2024 11:10:38 +0000 Message-ID: <4f4f008b-bde1-4551-ae24-db2c0778eb27@suse.cz> Date: Thu, 15 Feb 2024 12:10:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 5/7] mm,page_owner: Display all stacks and their count Content-Language: en-US To: Oscar Salvador , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Marco Elver , Andrey Konovalov , Alexander Potapenko References: <20240214170157.17530-1-osalvador@suse.de> <20240214170157.17530-6-osalvador@suse.de> From: Vlastimil Babka In-Reply-To: <20240214170157.17530-6-osalvador@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 87180100010 X-Rspam-User: X-Stat-Signature: bpuf9w1pd47x4rdeaigiqgu1tgkudwnh X-Rspamd-Server: rspam03 X-HE-Tag: 1707995441-131846 X-HE-Meta: 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 a0+x5fgh JBmMb/6pDW+Qb3HrOxYF1UQpM5jK8e+hH3QVOgtV3Qn/T8JySkI09pUp+TCxhwAGkSYuGRjEPmTf6PMg3lI99rN00q7uxjueaM5pC6oRDjPojmj/X01ET3gtm1qDcGqXsY1I+8usZfqiazGG+8wokOWQZxZl0fBv8jkgBjfVteSuql5B3IKXKFopDOp/N9VKUoPujprza9n7/bEDvq1BmdSnKkYmNMKkpzvYF74k5vtaJhyFX2in3+nJF31o74EEXbeC53dsfrNWo9/pGSlEY+Mc8wGQyvs5LbccGCyjnrLCotxsuR2QbAS2AC4yrbNvu7PkEftNe0L1InnIqwTH0sl617EwG4SYWSUNxGedAluhCmK0= 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 2/14/24 18:01, Oscar Salvador wrote: > This patch adds a new directory called 'page_owner_stacks' under > /sys/kernel/debug/, with a file called 'show_stacks' in it. > Reading from that file will show all stacks that were added by page_owner > followed by their counting, giving us a clear overview of stack <-> count > relationship. > > E.g: > > prep_new_page+0xa9/0x120 > get_page_from_freelist+0x801/0x2210 > __alloc_pages+0x18b/0x350 > alloc_pages_mpol+0x91/0x1f0 > folio_alloc+0x14/0x50 > filemap_alloc_folio+0xb2/0x100 > __filemap_get_folio+0x14a/0x490 > ext4_write_begin+0xbd/0x4b0 [ext4] > generic_perform_write+0xc1/0x1e0 > ext4_buffered_write_iter+0x68/0xe0 [ext4] > ext4_file_write_iter+0x70/0x740 [ext4] > vfs_write+0x33d/0x420 > ksys_write+0xa5/0xe0 > do_syscall_64+0x80/0x160 > entry_SYSCALL_64_after_hwframe+0x6e/0x76 > stack_count: 4578 > > The seq stack_{start,next} functions will iterate through the list > stack_list in order to print all stacks. > > Signed-off-by: Oscar Salvador > Acked-by: Marco Elver Reviewed-by: Vlastimil Babka ... > +static int stack_print(struct seq_file *m, void *v) > +{ > + int i; > + struct stack *stack = v; > + unsigned long *entries; > + unsigned long nr_entries; > + struct stack_record *stack_record = stack->stack_record; > + > + nr_entries = stack_record->size; > + entries = stack_record->entries; > + > + if (!nr_entries || nr_entries < 0 || > + refcount_read(&stack_record->count) < 2) > + return 0; > + > + for (i = 0; i < nr_entries; i++) > + seq_printf(m, " %pS\n", (void *)entries[i]); > + seq_printf(m, "stack_count: %d\n\n", refcount_read(&stack_record->count)); So count - 1 here to report actual usage, as explained in reply to 4/7?