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Mon, 05 Sep 2022 03:10:28 +0000 From: Oscar Salvador To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Vlastimil Babka , Eric Dumazet , Waiman Long , Suren Baghdasaryan , Marco Elver , Andrey Konovalov , Alexander Potapenko , Oscar Salvador Subject: [PATCH v2 2/3] mm, page_owner: Add page_owner_stacks file to print out only stacks and their counter Date: Mon, 5 Sep 2022 05:10:11 +0200 Message-Id: <20220905031012.4450-3-osalvador@suse.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220905031012.4450-1-osalvador@suse.de> References: <20220905031012.4450-1-osalvador@suse.de> MIME-Version: 1.0 ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=xmxC5alW; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=EkSlzIos; spf=pass (imf08.hostedemail.com: domain of osalvador@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de ARC-Seal: i=1; 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spf=pass (imf08.hostedemail.com: domain of osalvador@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de X-Rspam-User: X-Stat-Signature: 3j5f8w67czypihu7gwfikdyaq8ywras3 X-Rspamd-Queue-Id: 10E2616006F X-Rspamd-Server: rspam05 X-HE-Tag: 1662347429-189350 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: We might be only interested in knowing about stacks <-> count relationship, so instead of having to fiddle with page_owner output and screen through pfns, let us add a new file called 'page_owner_stacks' that does just that. By cating such file, we will get all the stacktraces followed by its counter, so we can have a more global view. Signed-off-by: Oscar Salvador Reported-by: kernel test robot --- include/linux/stackdepot.h | 1 + lib/stackdepot.c | 40 ++++++++++++++++++++++++++++++++++++++ mm/page_owner.c | 25 ++++++++++++++++++++++++ 3 files changed, 66 insertions(+) diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h index 4e3a88f135ee..19d3f8295df8 100644 --- a/include/linux/stackdepot.h +++ b/include/linux/stackdepot.h @@ -25,6 +25,7 @@ depot_stack_handle_t __stack_depot_save(unsigned long *entries, gfp_t gfp_flags, bool can_alloc, enum stack_depot_action action); void stack_depot_dec_count(depot_stack_handle_t handle); +int stack_depot_print_stacks_threshold(char *buf, size_t size, loff_t *pos); /* * Every user of stack depot has to call stack_depot_init() during its own init diff --git a/lib/stackdepot.c b/lib/stackdepot.c index a806ef58a385..a198b2dbe3fb 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -565,3 +565,43 @@ depot_stack_handle_t stack_depot_save_action(unsigned long *entries, return __stack_depot_save(entries, nr_entries, alloc_flags, true, action); } EXPORT_SYMBOL_GPL(stack_depot_save_action); + +int stack_depot_print_stacks_threshold(char *buf, size_t size, loff_t *pos) +{ + int i = *pos, ret = 0; + struct stack_record **stacks, *stack; + static struct stack_record *last = NULL; + unsigned long stack_table_entries = stack_hash_mask + 1; + + /* Continue from the last stack if we have one */ + if (last) { + stack = last->next; + } else { +new_table: + stacks = &stack_table[i]; + stack = (struct stack_record *)stacks; + } + + for (; stack; stack = stack->next) { + if (!stack->size || stack->size < 0 || + stack->size > size || stack->handle.valid != 1 || + refcount_read(&stack->count) < 1) + continue; + + ret += stack_trace_snprint(buf, size, stack->entries, stack->size, 0); + ret += scnprintf(buf + ret, size - ret, "stack count: %d\n\n", + refcount_read(&stack->count)); + last = stack; + return ret; + } + + i++; + *pos = i; + last = NULL; + + /* Keep looking all tables for valid stacks */ + if (i < stack_table_entries) + goto new_table; + + return 0; +} diff --git a/mm/page_owner.c b/mm/page_owner.c index 8730f377fa91..d88e6b4aefa0 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -664,6 +664,29 @@ static void init_early_allocated_pages(void) init_zones_in_node(pgdat); } +static ssize_t read_page_owner_stacks(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + char *kbuf; + int ret = 0; + + count = min_t(size_t, count, PAGE_SIZE); + kbuf = kmalloc(count, GFP_KERNEL); + if (!kbuf) + return -ENOMEM; + + ret += stack_depot_print_stacks_threshold(kbuf, count, pos); + if (copy_to_user(buf, kbuf, ret)) + ret = -EFAULT; + + kfree(kbuf); + return ret; +} + +static const struct file_operations proc_page_owner_stacks = { + .read = read_page_owner_stacks, +}; + static const struct file_operations proc_page_owner_operations = { .read = read_page_owner, }; @@ -677,6 +700,8 @@ static int __init pageowner_init(void) debugfs_create_file("page_owner", 0400, NULL, NULL, &proc_page_owner_operations); + debugfs_create_file("page_owner_stacks", 0400, NULL, NULL, + &proc_page_owner_stacks); return 0; }