Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 596D8C636D3 for ; Mon, 30 Jan 2023 20:50:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229701AbjA3Uu4 (ORCPT ); Mon, 30 Jan 2023 15:50:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229475AbjA3Uuy (ORCPT ); Mon, 30 Jan 2023 15:50:54 -0500 Received: from out-223.mta0.migadu.com (out-223.mta0.migadu.com [IPv6:2001:41d0:1004:224b::df]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22A507ABF for ; Mon, 30 Jan 2023 12:50:53 -0800 (PST) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1675111851; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TXUvy5WDZhr7BlKZ84VBiDQ9FKi0bXR5FVmrmN5uemo=; b=qTAqH/h3lvp3LBinh9ZgKXdhYP02imBJEuB8uqH1iUms1FkvE7RqMS6kgwiVfxPo6dPFiZ INjsSD6+m11nC0jZlXtAXeRY8JnQiDDTw74kkvq8iy8WIY5f1IjA3puf+2wSsDQv7yH1KS kCzz9lKkR7o1ZLchiqq6nGUmdZMJN3g= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko Cc: Andrey Konovalov , Vlastimil Babka , kasan-dev@googlegroups.com, Evgenii Stepanov , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH 06/18] lib/stackdepot: annotate init and early init functions Date: Mon, 30 Jan 2023 21:49:30 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrey Konovalov Add comments to stack_depot_early_init and stack_depot_init to explain certain parts of their implementation. Also add a pr_info message to stack_depot_early_init similar to the one in stack_depot_init. Also move the scale variable in stack_depot_init to the scope where it is being used. Signed-off-by: Andrey Konovalov --- lib/stackdepot.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 6e8aef12cf89..b06f6a5caa83 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -115,24 +115,34 @@ void __init stack_depot_request_early_init(void) __stack_depot_early_init_requested = true; } +/* Allocates a hash table via memblock. Can only be used during early boot. */ int __init stack_depot_early_init(void) { unsigned long entries = 0; - /* This is supposed to be called only once, from mm_init() */ + /* This function must be called only once, from mm_init(). */ if (WARN_ON(__stack_depot_early_init_passed)) return 0; - __stack_depot_early_init_passed = true; + /* + * If KASAN is enabled, use the maximum order: KASAN is frequently used + * in fuzzing scenarios, which leads to a large number of different + * stack traces being stored in stack depot. + */ if (kasan_enabled() && !stack_hash_order) stack_hash_order = STACK_HASH_ORDER_MAX; if (!__stack_depot_early_init_requested || stack_depot_disabled) return 0; + /* + * If stack_hash_order is not set, leave entries as 0 to rely on the + * automatic calculations performed by alloc_large_system_hash. + */ if (stack_hash_order) - entries = 1UL << stack_hash_order; + entries = 1UL << stack_hash_order; + pr_info("allocating hash table via alloc_large_system_hash\n"); stack_table = alloc_large_system_hash("stackdepot", sizeof(struct stack_record *), entries, @@ -142,7 +152,6 @@ int __init stack_depot_early_init(void) &stack_hash_mask, 1UL << STACK_HASH_ORDER_MIN, 1UL << STACK_HASH_ORDER_MAX); - if (!stack_table) { pr_err("hash table allocation failed, disabling\n"); stack_depot_disabled = true; @@ -152,6 +161,7 @@ int __init stack_depot_early_init(void) return 0; } +/* Allocates a hash table via kvmalloc. Can be used after boot. */ int stack_depot_init(void) { static DEFINE_MUTEX(stack_depot_init_mutex); @@ -160,11 +170,16 @@ int stack_depot_init(void) mutex_lock(&stack_depot_init_mutex); if (!stack_depot_disabled && !stack_table) { unsigned long entries; - int scale = STACK_HASH_SCALE; + /* + * Similarly to stack_depot_early_init, use stack_hash_order + * if assigned, and rely on automatic scaling otherwise. + */ if (stack_hash_order) { entries = 1UL << stack_hash_order; } else { + int scale = STACK_HASH_SCALE; + entries = nr_free_buffer_pages(); entries = roundup_pow_of_two(entries); @@ -179,7 +194,7 @@ int stack_depot_init(void) if (entries > 1UL << STACK_HASH_ORDER_MAX) entries = 1UL << STACK_HASH_ORDER_MAX; - pr_info("allocating hash table of %lu entries with kvcalloc\n", + pr_info("allocating hash table of %lu entries via kvcalloc\n", entries); stack_table = kvcalloc(entries, sizeof(struct stack_record *), GFP_KERNEL); if (!stack_table) { -- 2.25.1