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 E061B1EBFF5; Tue, 15 Oct 2024 12:09:04 +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=1728994145; cv=none; b=VKXBG2vmeFa6QsbgZS1/lg0XI04oobip9271YUmIs2JDazzgDIuKo3VoLOOfDBGOIgE3pguJFrZTG+K3uP7jGAbK/cjhJZ3tJDugZ7uOAVzNeut5HAGxDyrDLsjn9ntdLXrqpHdS6kBX1DpB2dyNxW6bFqoOBEFw5KJH5AKzac0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728994145; c=relaxed/simple; bh=8eGsQ0YgmLJW8HqxjIGpMmbL1PHuDVL+IB/6ROScMF4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uH7WCnVt+7kjf25B5jzjyjcWzvKidtZ2iSU+5ZLRvvrgcj01Z+5mW+ajeUdV6kyKom08ZE9HkSiFkBpVqaHIf9VDhbeX/EIakbif+vFUe9o0MeFXUjZ3BS3JDf6N/ddXoqbJQshmzzofMYu4+b54Wqnp/t/QZp0ALECsNLRHzkE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EYcuYWZX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EYcuYWZX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21216C4CEC6; Tue, 15 Oct 2024 12:09:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728994144; bh=8eGsQ0YgmLJW8HqxjIGpMmbL1PHuDVL+IB/6ROScMF4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EYcuYWZXxBLoFjwBeHhD9eCEH2/dwFE6d4xQn6Zm9hV41VyKEYtpqws8wVW5nhGjt liX/0hRkins6ntA7m8uUlSTQalT6AivfmDVQ2IRSn4YrTNae3iBw1yqYeX0JF3RbWi VmdkgDAecFnkgxmyRsVl67OhcaWx0g8KPQw1ASTc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mark Rutland , Mathieu Desnoyers , Andrew Morton , Tim Chen , Vincent Donnefort , Sven Schnelle , Mete Durlu , "Masami Hiramatsu (Google)" , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 5.15 589/691] tracing: Have saved_cmdlines arrays all in one allocation Date: Tue, 15 Oct 2024 13:28:57 +0200 Message-ID: <20241015112503.726171690@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015112440.309539031@linuxfoundation.org> References: <20241015112440.309539031@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt (Google) [ Upstream commit 0b18c852cc6fb8284ac0ab97e3e840974a6a8a64 ] The saved_cmdlines have three arrays for mapping PIDs to COMMs: - map_pid_to_cmdline[] - map_cmdline_to_pid[] - saved_cmdlines The map_pid_to_cmdline[] is PID_MAX_DEFAULT in size and holds the index into the other arrays. The map_cmdline_to_pid[] is a mapping back to the full pid as it can be larger than PID_MAX_DEFAULT. And the saved_cmdlines[] just holds the COMMs associated to the pids. Currently the map_pid_to_cmdline[] and saved_cmdlines[] are allocated together (in reality the saved_cmdlines is just in the memory of the rounding of the allocation of the structure as it is always allocated in powers of two). The map_cmdline_to_pid[] array is allocated separately. Since the rounding to a power of two is rather large (it allows for 8000 elements in saved_cmdlines), also include the map_cmdline_to_pid[] array. (This drops it to 6000 by default, which is still plenty for most use cases). This saves even more memory as the map_cmdline_to_pid[] array doesn't need to be allocated. Link: https://lore.kernel.org/linux-trace-kernel/20240212174011.068211d9@gandalf.local.home/ Link: https://lore.kernel.org/linux-trace-kernel/20240220140703.182330529@goodmis.org Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Tim Chen Cc: Vincent Donnefort Cc: Sven Schnelle Cc: Mete Durlu Fixes: 44dc5c41b5b1 ("tracing: Fix wasted memory in saved_cmdlines logic") Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a1d034b7300ac..b199b0c7cba09 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2241,6 +2241,10 @@ struct saved_cmdlines_buffer { }; static struct saved_cmdlines_buffer *savedcmd; +/* Holds the size of a cmdline and pid element */ +#define SAVED_CMDLINE_MAP_ELEMENT_SIZE(s) \ + (TASK_COMM_LEN + sizeof((s)->map_cmdline_to_pid[0])) + static inline char *get_saved_cmdlines(int idx) { return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN]; @@ -2255,7 +2259,6 @@ static void free_saved_cmdlines_buffer(struct saved_cmdlines_buffer *s) { int order = get_order(sizeof(*s) + s->cmdline_num * TASK_COMM_LEN); - kfree(s->map_cmdline_to_pid); kmemleak_free(s); free_pages((unsigned long)s, order); } @@ -2268,7 +2271,7 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) int order; /* Figure out how much is needed to hold the given number of cmdlines */ - orig_size = sizeof(*s) + val * TASK_COMM_LEN; + orig_size = sizeof(*s) + val * SAVED_CMDLINE_MAP_ELEMENT_SIZE(s); order = get_order(orig_size); size = 1 << (order + PAGE_SHIFT); page = alloc_pages(GFP_KERNEL, order); @@ -2280,16 +2283,11 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) memset(s, 0, sizeof(*s)); /* Round up to actual allocation */ - val = (size - sizeof(*s)) / TASK_COMM_LEN; + val = (size - sizeof(*s)) / SAVED_CMDLINE_MAP_ELEMENT_SIZE(s); s->cmdline_num = val; - s->map_cmdline_to_pid = kmalloc_array(val, - sizeof(*s->map_cmdline_to_pid), - GFP_KERNEL); - if (!s->map_cmdline_to_pid) { - free_saved_cmdlines_buffer(s); - return NULL; - } + /* Place map_cmdline_to_pid array right after saved_cmdlines */ + s->map_cmdline_to_pid = (unsigned *)&s->saved_cmdlines[val * TASK_COMM_LEN]; s->cmdline_idx = 0; memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP, -- 2.43.0