From patchwork Mon Feb 10 15:44:17 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 13968092 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 6D603241C89; Mon, 10 Feb 2025 15:44:22 +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=1739202262; cv=none; b=Aa+1Zw3P98lr079/7RJze8aeWGFiOEVlQGXJoBwJqiQ6/rNrg+RFaMTLdcnbKjZrRvmoK04fzx8CTcznrEmKeXvSaCDmOJKQCd8IhDW5vTcbEX9WgJQn2W806MkJSV2DOCww7QPITYqGNq5hQjclanJjPbt9NiPxIIZ98AJplRA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739202262; c=relaxed/simple; bh=a1YPttl+qkE5UPQa+Ej7ligSEOM91uyMY3DsNFx/Ops=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ncjdGAtb5RgHJDaS+UAvFp5AMjtwDl0wXTNipxuchUmDNO7YXnZHLiwAaKrIHg0BYTPC0yOj0l2mqDEkJmovowuSibH4ZNah1wAljz4yFsf+mP+DjL7YxIOyubjix3UasRUYwIPw8L6HUhOTIzGYazYZvAaoqXAzvgaLVc2SgcU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=buqlvxwG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="buqlvxwG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62C30C4CED1; Mon, 10 Feb 2025 15:44:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739202262; bh=a1YPttl+qkE5UPQa+Ej7ligSEOM91uyMY3DsNFx/Ops=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=buqlvxwGzRgS9DeXYQ+MjvkLCJEHL0Wxn+Ebq5PZaum/c6jXytv/wRu/7TBWw0nMB 3NKC69Nu1bHvKFBu9t2x1Y94ckDNY0NCmhdTY35fZUOYGvBYYmNVx3vpZSuvCzMUpT QvUsaQK9isnSriujDOoe25jOeb9xoXF05Hyx7ofUDk4nCCEwYtJ04fwU3VwhBHxd+C uj6DtDZvXQ0h8ZcIojWZxaVA+ttLh7ZLiL+fryG4Qt3BNxHK1S9bfL+ykMP3XlofPQ ybOsx5CQi4ZRZwVsogW2DurSfr5tWQuhBBjVMUsxhQ43PXnrwT43eTRwKm9Lc1yzy/ ptcQNsBApq7kQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Mathieu Desnoyers , Andrew Morton Subject: [RFC PATCH v2 3/3] tracing: Freeable reserved ring buffer Date: Tue, 11 Feb 2025 00:44:17 +0900 Message-ID: <173920225773.826592.6428338529686044470.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <173920222697.826592.3726270716809214055.stgit@devnote2> References: <173920222697.826592.3726270716809214055.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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=20M:2M:trace trace_instance=boot_mapped^traceoff@trace" # free total used free shared buff/cache available Mem: 1994720 45292 1931960 14908 17468 1915920 Swap: 0 0 0 # rmdir /sys/kernel/tracing/instances/boot_mapped/ # free total used free shared buff/cache available Mem: 1994720 17204 1960060 14912 17456 1944012 Swap: 0 0 0 Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace.c | 17 +++++++++++++++-- kernel/trace/trace.h | 1 + 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index dde8000a5614..113ad3179ecd 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9594,6 +9594,9 @@ 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); } static void init_trace_flags_index(struct trace_array *tr) @@ -9755,6 +9758,7 @@ trace_array_create_systems(const char *name, const char *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); @@ -9857,8 +9861,10 @@ static int __remove_instance(struct trace_array *tr) int i; /* Reference counter for a newly created trace array = 1. */ - if (tr->ref > 1 || (tr->current_trace && tr->trace_ref)) + if (tr->ref > 1 || (tr->current_trace && tr->trace_ref)) { + pr_info("Instance is busy: ref %d trace_ref %d\n", tr->ref, tr->trace_ref); return -EBUSY; + } list_del(&tr->list); @@ -9881,6 +9887,11 @@ static int __remove_instance(struct trace_array *tr) free_trace_buffers(tr); clear_tracing_err_log(tr); + if (tr->range_name) { + reserved_mem_release_by_name(tr->range_name); + kfree(tr->range_name); + } + for (i = 0; i < tr->nr_topts; i++) { kfree(tr->topts[i].topts); } @@ -10740,6 +10751,7 @@ __init static void enable_instances(void) bool traceoff = false; char *flag_delim; char *addr_delim; + char *rname __free(kfree) = NULL; tok = strsep(&curr_str, ","); @@ -10796,6 +10808,7 @@ __init static void enable_instances(void) pr_warn("Failed to map boot instance %s to %s\n", name, tok); continue; } + rname = kstrdup(tok, GFP_KERNEL); } if (start) { @@ -10832,7 +10845,7 @@ __init static void enable_instances(void) */ if (start) { tr->flags |= TRACE_ARRAY_FL_BOOT | TRACE_ARRAY_FL_LAST_BOOT; - tr->ref++; + tr->range_name = no_free_ptr(rname); } while ((tok = strsep(&curr_str, ","))) { diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 47c0742fe9ec..ae8f7fac6592 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; int nr_modules; long *module_delta;