From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 347FE4F888 for ; Mon, 12 Feb 2024 23:28:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707780522; cv=none; b=nlUQr0Fg9DWT1gAdL/i0b43oyPVnW4O8BqIxkwxXDgD0JHPokfL3T2U0RBDBuiHhiPJw53ShfwH7yQEQMUk0AcQF2dDKgLikuCA/vh2OnqSQ6IdCWc2TKmul5vD1zWYS+Q07lDubAXFGL0JPauhrMj1CCLSMJvSbd2/Fjr4DuzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707780522; c=relaxed/simple; bh=1P9ykQ1FxVHufaRwCzbdEqEO+7F0DXHiY/3I8jD5/xs=; h=Date:To:From:Subject:Message-Id; b=kBzn8WORlGudJlkVsvH9eKkz0yLzMHU4QUWI1DITh+CIZ8i24mrkDcqQ/0CMrUeQAuJPndaJIqmbnwA5QZKM3Mk3cmxJBSWPz0TtI0zYgsGTixaZ9A/VjdFk/mQrvufIKLptiZ89GgURuJiteXk6V+82a5CXzW4IhUDsOv75lEI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=t57I0BUC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="t57I0BUC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1202C433F1; Mon, 12 Feb 2024 23:28:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1707780521; bh=1P9ykQ1FxVHufaRwCzbdEqEO+7F0DXHiY/3I8jD5/xs=; h=Date:To:From:Subject:From; b=t57I0BUCa7CUcHn+8tdQ7wxLjez8YRgCdxL/niWEtEJtea0LOdkV7ZBYkAeRz6Hll MJA66wVKGHE2bpg9PZFJfhnvl/RFcq3wy0183hwJKhgMxF6Pa3xOMxmjpqHnEaK1YX K/9jK9DlqQfRPXcbbdEvZPQ+I7QKcQYOSm7W2JsM= Date: Mon, 12 Feb 2024 15:28:41 -0800 To: mm-commits@vger.kernel.org,vbabka@suse.cz,mhocko@suse.com,glider@google.com,elver@google.com,andreyknvl@gmail.com,osalvador@suse.de,akpm@linux-foundation.org From: Andrew Morton Subject: + mmpage_owner-display-all-stacks-and-their-count.patch added to mm-unstable branch Message-Id: <20240212232841.A1202C433F1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm,page_owner: display all stacks and their count has been added to the -mm mm-unstable branch. Its filename is mmpage_owner-display-all-stacks-and-their-count.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmpage_owner-display-all-stacks-and-their-count.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Oscar Salvador Subject: mm,page_owner: display all stacks and their count Date: Mon, 12 Feb 2024 23:30:27 +0100 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. Link: https://lkml.kernel.org/r/20240212223029.30769-4-osalvador@suse.de Signed-off-by: Oscar Salvador Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Marco Elver Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/page_owner.c | 99 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 98 insertions(+), 1 deletion(-) --- a/mm/page_owner.c~mmpage_owner-display-all-stacks-and-their-count +++ a/mm/page_owner.c @@ -84,7 +84,12 @@ static void add_stack_record_to_list(str stack_list = stack; } else { stack->next = stack_list; - stack_list = stack; + /* This pairs with smp_load_acquire() from function + * stack_start(). This guarantees that stack_start() + * will see an updated stack_list before starting to + * traverse the list. + */ + smp_store_release(&stack_list, stack); } spin_unlock_irqrestore(&stack_list_lock, flags); } @@ -792,8 +797,97 @@ static const struct file_operations proc .llseek = lseek_page_owner, }; +static void *stack_start(struct seq_file *m, loff_t *ppos) +{ + struct stack *stack; + + if (*ppos == -1UL) + return NULL; + + if (!*ppos) { + /* + * This pairs with smp_store_release() from function + * add_stack_record_to_list(), so we get a consistent + * value of stack_list. + */ + stack = smp_load_acquire(&stack_list); + } else { + stack = m->private; + stack = stack->next; + } + + m->private = stack; + + return stack; +} + +static void *stack_next(struct seq_file *m, void *v, loff_t *ppos) +{ + struct stack *stack = v; + + stack = stack->next; + *ppos = stack ? *ppos + 1 : -1UL; + m->private = stack; + + return stack; +} + +static int stack_print(struct seq_file *m, void *v) +{ + char *buf; + int ret = 0; + struct stack *stack = v; + struct stack_record *stack_record = stack->stack_record; + + if (!stack_record->size || stack_record->size < 0 || + refcount_read(&stack_record->count) < 2) + return 0; + + buf = kzalloc(PAGE_SIZE, GFP_KERNEL); + + ret += stack_trace_snprint(buf, PAGE_SIZE, stack_record->entries, + stack_record->size, 0); + if (!ret) + goto out; + + scnprintf(buf + ret, PAGE_SIZE - ret, "stack_count: %d\n\n", + refcount_read(&stack_record->count)); + + seq_printf(m, buf); + seq_puts(m, "\n\n"); +out: + kfree(buf); + + return 0; +} + +static void stack_stop(struct seq_file *m, void *v) +{ +} + +static const struct seq_operations page_owner_stack_op = { + .start = stack_start, + .next = stack_next, + .stop = stack_stop, + .show = stack_print +}; + +static int page_owner_stack_open(struct inode *inode, struct file *file) +{ + return seq_open_private(file, &page_owner_stack_op, 0); +} + +static const struct file_operations page_owner_stack_operations = { + .open = page_owner_stack_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + static int __init pageowner_init(void) { + struct dentry *dir; + if (!static_branch_unlikely(&page_owner_inited)) { pr_info("page_owner is disabled\n"); return 0; @@ -801,6 +895,9 @@ static int __init pageowner_init(void) debugfs_create_file("page_owner", 0400, NULL, NULL, &proc_page_owner_operations); + dir = debugfs_create_dir("page_owner_stacks", NULL); + debugfs_create_file("show_stacks", 0400, dir, NULL, + &page_owner_stack_operations); return 0; } _ Patches currently in -mm which might be from osalvador@suse.de are lib-stackdepot-move-stack_record-struct-definition-into-the-header.patch mmpage_owner-implement-the-tracking-of-the-stacks-count.patch mmpage_owner-display-all-stacks-and-their-count.patch mmpage_owner-filter-out-stacks-by-a-threshold.patch mmpage_owner-update-documentation-regarding-page_owner_stacks.patch