From patchwork Wed Feb 14 16:20:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13556731 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 004105C8F9; Wed, 14 Feb 2024 16:19:16 +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=1707927557; cv=none; b=uEIb5Kn67WL84c6dxDkn8/kHe19M+RKkCK59ovxZS8Xu59wrhUzMELEN710C7AcwrqzsOH3R77bgSnwax8zc5fpZCUHE95G2YrTKMkPJe6wVTXyQmzAiyLu/IxCK/feJjuXHlTAb8eTTztCPoOwcmx1tsfeKZeLBGka2MvVFrhY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707927557; c=relaxed/simple; bh=FgoKfr/kiklKS0MR9RdlQzsKfKHg1gO0Og/ldxC+h6Q=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=vGt2G6MRa6F76oieZZHtXL2ctZDPfRuqNlDTqOaEWbt0FWDTGIRItWgcuH/QZfXKLJBoptOeW6U4Ecjz4MqqMB6l4igN1t8csTv6Eqyup1pUX9wehIlI3HDA1lDovgOfTRyvXQ0xsAQZnqGX3G9nwaUvbrHC4CuHpUFL+EZiD2Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB86CC433F1; Wed, 14 Feb 2024 16:19:15 +0000 (UTC) Date: Wed, 14 Feb 2024 11:20:46 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mathieu Desnoyers , Kalle Valo Subject: [PATCH v2] tracing: Inform kmemleak of saved_cmdlines allocation Message-ID: <20240214112046.09a322d6@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" The allocation of the struct saved_cmdlines_buffer structure changed from: s = kmalloc(sizeof(*s), GFP_KERNEL); s->saved_cmdlines = kmalloc_array(TASK_COMM_LEN, val, GFP_KERNEL); to: orig_size = sizeof(*s) + val * TASK_COMM_LEN; order = get_order(orig_size); size = 1 << (order + PAGE_SHIFT); page = alloc_pages(GFP_KERNEL, order); if (!page) return NULL; s = page_address(page); memset(s, 0, sizeof(*s)); s->saved_cmdlines = kmalloc_array(TASK_COMM_LEN, val, GFP_KERNEL); Where that s->saved_cmdlines allocation looks to be a dangling allocation to kmemleak. That's because kmemleak only keeps track of kmalloc() allocations. For allocations that use page_alloc() directly, the kmemleak needs to be explicitly informed about it. Add kmemleak_alloc() and kmemleak_free() around the page allocation so that it doesn't give the following false positive: unreferenced object 0xffff8881010c8000 (size 32760): comm "swapper", pid 0, jiffies 4294667296 hex dump (first 32 bytes): ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ backtrace (crc ae6ec1b9): [] kmemleak_alloc+0x45/0x80 [] __kmalloc_large_node+0x10d/0x190 [] __kmalloc+0x3b1/0x4c0 [] allocate_cmdlines_buffer+0x113/0x230 [] tracer_alloc_buffers.isra.0+0x124/0x460 [] early_trace_init+0x14/0xa0 [] start_kernel+0x12e/0x3c0 [] x86_64_start_reservations+0x18/0x30 [] x86_64_start_kernel+0x7b/0x80 [] secondary_startup_64_no_verify+0x15e/0x16b Link: https://lore.kernel.org/linux-trace-kernel/87r0hfnr9r.fsf@kernel.org/ Fixes: 44dc5c41b5b1 ("tracing: Fix wasted memory in saved_cmdlines logic") Reported-by: Kalle Valo Tested-by: Kalle Valo Signed-off-by: Steven Rostedt (Google) Tested-by: Kalle Valo --- Changes since v1: https://lore.kernel.org/linux-trace-kernel/20240214102614.1a1405be@gandalf.local.home/ - Rebased on my urgent branch that still has the code in trace.c and not my for-next local branch that moved it to trace_sched_switch.c kernel/trace/trace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index aa54810e8b56..8198bfc54b58 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include #include @@ -2339,6 +2340,7 @@ 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); } @@ -2358,6 +2360,7 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) return NULL; s = page_address(page); + kmemleak_alloc(s, size, 1, GFP_KERNEL); memset(s, 0, sizeof(*s)); /* Round up to actual allocation */