From nobody Sun Feb 8 11:44:00 2026 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 42D0178B67 for ; Thu, 15 Feb 2024 21:38:10 +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=1708033090; cv=none; b=XqAZXecsxZurXe2mAgHFW/JRiGe/Og+gs1N34Qh3wESaoaeHTf8eb27fK5cTkCvIq2ap5aHJ6d5uV4whkBPUn2Dj6FIoKIOU+w52TldobU8+h3Z0gQdxMqjWnNoW5ger10GITKV90NpkUQLfI/DDAFAV9rdJeisGQBxdawHKf34= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708033090; c=relaxed/simple; bh=7CiiHSVOUXcrGH/JJmVwslHSn8uV127w5zLLdzyghM4=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=PEmsGcops3v84L7sL6wNiT/KbYopwy8sEH9vlv1r+SbKsGIyQcDLHwwvKpz7GUui8aOpjPYiXpyJsP2ToB/9VjX8py0fKSuQLEOravQAmM8QSocuGZtWJH/1N7wEukPe4FpX0oDmr/OrdTB5nx4WEd65PUn4UQ1ZSCV9L2F0y0w= 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 D51B0C43394; Thu, 15 Feb 2024 21:38:09 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rajSK-00000000edY-2j0P; Thu, 15 Feb 2024 16:39:44 -0500 Message-ID: <20240215213944.508142048@goodmis.org> User-Agent: quilt/0.67 Date: Thu, 15 Feb 2024 16:39:17 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Catalin Marinas , Kalle Valo Subject: [for-linus][PATCH 1/4] tracing: Inform kmemleak of saved_cmdlines allocation References: <20240215213916.385127578@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" The allocation of the struct saved_cmdlines_buffer structure changed from: s =3D kmalloc(sizeof(*s), GFP_KERNEL); s->saved_cmdlines =3D kmalloc_array(TASK_COMM_LEN, val, GFP_KERNEL); to: orig_size =3D sizeof(*s) + val * TASK_COMM_LEN; order =3D get_order(orig_size); size =3D 1 << (order + PAGE_SHIFT); page =3D alloc_pages(GFP_KERNEL, order); if (!page) return NULL; s =3D page_address(page); memset(s, 0, sizeof(*s)); s->saved_cmdlines =3D 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/ Link: https://lore.kernel.org/linux-trace-kernel/20240214112046.09a322d6@ga= ndalf.local.home Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Catalin Marinas Fixes: 44dc5c41b5b1 ("tracing: Fix wasted memory in saved_cmdlines logic") Reported-by: Kalle Valo Tested-by: Kalle Valo Signed-off-by: Steven Rostedt (Google) --- 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_c= mdlines_buffer *s) int order =3D get_order(sizeof(*s) + s->cmdline_num * TASK_COMM_LEN); =20 kfree(s->map_cmdline_to_pid); + kmemleak_free(s); free_pages((unsigned long)s, order); } =20 @@ -2358,6 +2360,7 @@ static struct saved_cmdlines_buffer *allocate_cmdline= s_buffer(unsigned int val) return NULL; =20 s =3D page_address(page); + kmemleak_alloc(s, size, 1, GFP_KERNEL); memset(s, 0, sizeof(*s)); =20 /* Round up to actual allocation */ --=20 2.43.0