From nobody Tue Feb 10 22:15:18 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 11A78C133 for ; Thu, 27 Feb 2025 00:12:12 +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=1740615133; cv=none; b=ZbFd4YOxWs3AMIRF+egK7bsx/IFVAzylGJYBPIBxf3akB3skCqoQp1r4/VUz5AAAaDqigytVNqWxjoOV5uSKGOSA3EBLRCaNvzrYQKqQnnlSJ8N0KXmLaUIcBwyJm+zOgpMXAPuDb4hcnuGDs8CduI60WjWzT+YnTW9zzQjAtNw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740615133; c=relaxed/simple; bh=930gZKhLgdCHbmsCso2yuEEbwWgxnmJbIbvm5UQU7Ig=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=JKD+NMk+xsUYSklGGcipE8xypWBf9ttOusKU/paloI8TI/e/LneKFIUyN3bHWNCsOuYjCB89A7VxHVC0OYl+q+fJeakhDh0I0ZveFuCQfj4cjsPwZekURwI1fZe1adL3ZpvBe5Y3b+wxnyk0Mu36/l5cPkKhuKDTNTSmbUZHTxw= 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 B3A9FC4CEEC; Thu, 27 Feb 2025 00:12:12 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1tnRWI-00000009XRX-3Ef3; Wed, 26 Feb 2025 19:12:54 -0500 Message-ID: <20250227001254.624778797@goodmis.org> User-Agent: quilt/0.68 Date: Wed, 26 Feb 2025 19:12:38 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Mike Rapoport Subject: [for-next][PATCH 3/3] tracing: Freeable reserved ring buffer References: <20250227001235.355892523@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: "Masami Hiramatsu (Google)" Make the ring buffer on reserved memory to be freeable. This allows us to free the trace instance on the reserved memory without changing cmdline and rebooting. Even if we can not change the kernel cmdline for security reason, we can release the reserved memory for the ring buffer as free (available) memory. For example, boot kernel with reserved memory; "reserve_mem=3D20M:2M:trace trace_instance=3Dboot_mapped^traceoff@trace" ~ # free total used free shared buff/cache avail= able Mem: 1995548 50544 1927568 14964 17436 191= 1480 Swap: 0 0 0 ~ # rmdir /sys/kernel/tracing/instances/boot_mapped/ [ 23.704023] Freeing reserve_mem:trace memory: 20476K ~ # free total used free shared buff/cache avail= able Mem: 2016024 41844 1956740 14968 17440 194= 0572 Swap: 0 0 0 Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Mike Rapoport Link: https://lore.kernel.org/173989134814.230693.18199312930337815629.stgi= t@devnote2 Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 13 ++++++++++++- kernel/trace/trace.h | 1 + 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 61458d8c3a61..b4bcb85094d9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9292,6 +9292,9 @@ static void free_trace_buffers(struct trace_array *tr) #ifdef CONFIG_TRACER_MAX_TRACE free_trace_buffer(&tr->max_buffer); #endif + + if (tr->range_addr_start) + vunmap((void *)tr->range_addr_start); } =20 static void init_trace_flags_index(struct trace_array *tr) @@ -9453,6 +9456,7 @@ trace_array_create_systems(const char *name, const ch= ar *systems, free_cpumask_var(tr->pipe_cpumask); free_cpumask_var(tr->tracing_cpumask); kfree_const(tr->system_names); + kfree(tr->range_name); kfree(tr->name); kfree(tr); =20 @@ -9579,6 +9583,11 @@ static int __remove_instance(struct trace_array *tr) free_trace_buffers(tr); clear_tracing_err_log(tr); =20 + if (tr->range_name) { + reserve_mem_release_by_name(tr->range_name); + kfree(tr->range_name); + } + for (i =3D 0; i < tr->nr_topts; i++) { kfree(tr->topts[i].topts); } @@ -10376,6 +10385,7 @@ __init static void enable_instances(void) bool traceoff =3D false; char *flag_delim; char *addr_delim; + char *rname __free(kfree) =3D NULL; =20 tok =3D strsep(&curr_str, ","); =20 @@ -10432,6 +10442,7 @@ __init static void enable_instances(void) pr_warn("Failed to map boot instance %s to %s\n", name, tok); continue; } + rname =3D kstrdup(tok, GFP_KERNEL); } =20 if (start) { @@ -10468,7 +10479,7 @@ __init static void enable_instances(void) */ if (start) { tr->flags |=3D TRACE_ARRAY_FL_BOOT; - tr->ref++; + tr->range_name =3D no_free_ptr(rname); } =20 while ((tok =3D strsep(&curr_str, ","))) { diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 9c21ba45b7af..93b6279d3da4 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -348,6 +348,7 @@ struct trace_array { unsigned int mapped; unsigned long range_addr_start; unsigned long range_addr_size; + char *range_name; long text_delta; long data_delta; =20 --=20 2.47.2