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 8F5295A4FD; Wed, 14 Feb 2024 14:44:47 +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=1707921887; cv=none; b=AMgtsnMz1SvKWIztpEhczSIFbMH/FKM8rq3DvEpUGWAmLbA5tEcGKZ6JTwwiaCSBRxBSEmUjdWfpqy8TyzNet6XJxHkPPEse3fzucI9tvKUpFtoi0+C+7+xOHnTpCnnR05/p4y5AhUg5ooycyUX/L3DeqvjLqZVi73x7xAoSgXM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707921887; c=relaxed/simple; bh=Q9eBesZ5QD6ZC02ZVDqG4p5BGWCeCIzNlp1bEssnMFs=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=IDLu0DGmjclzm9uuxi4lUUbs3MtzQJDpMZR+5F8zS4PN03HRAFEbsiQzMZxa5d7vrMx6FdWC+RGz1s2vaD51LbW1n1B0TDGVwGqlt38M/m3mWukjc4XZSPvbpbqaKiL2FyAFgQnnV/0S39uViBsBsdEo//nzpxkZ1XUWbe9uAXA= 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 816B7C433F1; Wed, 14 Feb 2024 14:44:46 +0000 (UTC) Date: Wed, 14 Feb 2024 09:46:17 -0500 From: Steven Rostedt To: Kalle Valo Cc: regressions@lists.linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Jeff Johnson Subject: Re: [regression] tracing: kmemleak warning in allocate_cmdlines_buffer() Message-ID: <20240214094617.1e6ec684@gandalf.local.home> In-Reply-To: <87r0hfnr9r.fsf@kernel.org> References: <87r0hfnr9r.fsf@kernel.org> 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 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 14 Feb 2024 14:50:56 +0200 Kalle Valo wrote: > Hi Steven, > > I upgraded our ath11k test setup to v6.8-rc4 and noticed a new kmemleak > warning in the log: Thanks for the report. > > 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 > > I don't see this warning in v6.8-rc3 and also reverting commit > 44dc5c41b5b1 ("tracing: Fix wasted memory in saved_cmdlines logic") > makes the warning go away. Let me know if you need more info or help > with testing, I see the warning every time so it's easy to reproduce. > Hmm, I changed the code a bit and I wonder if this is a false positive? Instead of allocating the structure via kmalloc() I now use it as part of a page. That is, the old code had: s = kmalloc(sizeof(*s), GFP_KERNEL); s->saved_cmdlines = kmalloc_array(TASK_COMM_LEN, val, GFP_KERNEL); Where as the new code has: 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); Does kmemleak handle structures that are assigned to alloc_pages() allocations? I don't think it does. I think we need to inform kmemleak about this. Does the following patch fix this for you? -- Steve diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c index e4fbcc3bede5..de4182224ea2 100644 --- a/kernel/trace/trace_sched_switch.c +++ b/kernel/trace/trace_sched_switch.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include "trace.h" @@ -190,6 +191,7 @@ 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); } @@ -210,6 +212,7 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) s = page_address(page); memset(s, 0, sizeof(*s)); + kmemleak_alloc(s, size, 1, GFP_KERNEL); /* Round up to actual allocation */ val = (size - sizeof(*s)) / TASK_COMM_LEN;