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 07A1C1D540; Sun, 27 Oct 2024 14:03:03 +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=1730037784; cv=none; b=uCZzzCOafdLfNdFC8DBIt3hdX/GEeyrtcXf1sFBW3dg9A4RYPm8ozazlLAiojpgX0g/VMtpNurd5nvmkzpEkA/bAJiYmt72KBjQziZ2HdyaYyKBSp9zbf2QuPbeQSDBXPcw58PJjY4emE1YyEdyESDU7qGVVy2lEDbJydJQ1rYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730037784; c=relaxed/simple; bh=LhoYjWPnw5QWHt7GC9qloa0rQmmKlS9JcCkIHsCUrXI=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=R2VoXWvLBkbLn+shfQdxguMYs2KynOyd+4HC7Z6996LveKcuDzigligSWiGsqcAvtToBlOkHDWjBeqA46h5WRu26eMSgmaacKVJzam+UOH8pzYU4/mzJ1b/YGsTH+azh0UnlXuwQgDc4SZUZKvrAY3CB7GmUMoEu2YYXqr3sn8Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GIrAL571; 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="GIrAL571" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA151C4CEC3; Sun, 27 Oct 2024 14:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730037783; bh=LhoYjWPnw5QWHt7GC9qloa0rQmmKlS9JcCkIHsCUrXI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=GIrAL57198rDy9Hctkx4eClyY3UHQPHYQz9cTB+qHBOzRkl9kmSFaAJqiZPxKAYlg FKQhNaYEalQNtMb+ry+p84SaVhaQbZ70JOtvxAHUpBYbloCMpQ9aksHPojUmq0eZvX qYqR+Bqzdsj9p5NTDjH1zgYsGpv+J9RgDtV3YhxyF1uG613b/ym83iwn604Cr6SxeI 16HYYSs/MKNtobg3fOI4Mvci5QanT16cBxWn0MULPP0t8pqPDPmkM8CeTOxqPgEz3b m9NFYpBE7QvW4yBZkOKLip+Uu0kVwnCDSmUHEMSU7hq6KqyskJtof42F3n7NChulon jz5Eqckc+L6gg== Date: Sun, 27 Oct 2024 23:02:59 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: LKML , Linux trace kernel , Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Ryan Roberts Subject: Re: [PATCH v2] fgraph: Give ret_stack its own kmem cache Message-Id: <20241027230259.d908b43b5d41833cebb9ff2c@kernel.org> In-Reply-To: <20241026063210.7d4910a7@rorschach.local.home> References: <20241026063210.7d4910a7@rorschach.local.home> X-Mailer: Sylpheed 3.8.0beta1 (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 Sat, 26 Oct 2024 06:32:10 -0400 Steven Rostedt wrote: > From: Steven Rostedt > > The ret_stack (shadow stack used by function graph infrastructure) is > created for every task on the system when function graph is enabled. Give > it its own kmem_cache. This will make it easier to see how much memory is > being used specifically for function graph shadow stacks. > > In the future, this size may change and may not be a power of two. Having > its own cache can also keep it from fragmenting memory. > Looks good to me. Acked-by: Masami Hiramatsu (Google) Thank youm > Signed-off-by: Steven Rostedt (Google) > --- > Changes since v1: https://lore.kernel.org/20241019152719.321772eb@rorschach.local.home > > - Rebased on top of urgent merged into for-next (uses guard(mutex) now) > > kernel/trace/fgraph.c | 33 ++++++++++++++++++++++++++++----- > 1 file changed, 28 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index 4ce87982966a..001abf376c0c 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -172,6 +172,8 @@ enum { > DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); > int ftrace_graph_active; > > +static struct kmem_cache *fgraph_stack_cachep; > + > static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE]; > static unsigned long fgraph_array_bitmask; > > @@ -1022,8 +1024,11 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) > int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE; > struct task_struct *g, *t; > > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return -ENOMEM; > + > for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) { > - ret_stack_list[i] = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + ret_stack_list[i] = kmem_cache_alloc(fgraph_stack_cachep, GFP_KERNEL); > if (!ret_stack_list[i]) { > start = 0; > end = i; > @@ -1054,7 +1059,7 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list) > rcu_read_unlock(); > free: > for (i = start; i < end; i++) > - kfree(ret_stack_list[i]); > + kmem_cache_free(fgraph_stack_cachep, ret_stack_list[i]); > return ret; > } > > @@ -1117,9 +1122,12 @@ void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) > if (ftrace_graph_active) { > unsigned long *ret_stack; > > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + > ret_stack = per_cpu(idle_ret_stack, cpu); > if (!ret_stack) { > - ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + ret_stack = kmem_cache_alloc(fgraph_stack_cachep, GFP_KERNEL); > if (!ret_stack) > return; > per_cpu(idle_ret_stack, cpu) = ret_stack; > @@ -1139,7 +1147,10 @@ void ftrace_graph_init_task(struct task_struct *t) > if (ftrace_graph_active) { > unsigned long *ret_stack; > > - ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL); > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + > + ret_stack = kmem_cache_alloc(fgraph_stack_cachep, GFP_KERNEL); > if (!ret_stack) > return; > graph_init_task(t, ret_stack); > @@ -1154,7 +1165,11 @@ void ftrace_graph_exit_task(struct task_struct *t) > /* NULL must become visible to IRQs before we free it: */ > barrier(); > > - kfree(ret_stack); > + if (ret_stack) { > + if (WARN_ON_ONCE(!fgraph_stack_cachep)) > + return; > + kmem_cache_free(fgraph_stack_cachep, ret_stack); > + } > } > > #ifdef CONFIG_DYNAMIC_FTRACE > @@ -1294,6 +1309,14 @@ int register_ftrace_graph(struct fgraph_ops *gops) > > guard(mutex)(&ftrace_lock); > > + if (!fgraph_stack_cachep) { > + fgraph_stack_cachep = kmem_cache_create("fgraph_stack", > + SHADOW_STACK_SIZE, > + SHADOW_STACK_SIZE, 0, NULL); > + if (!fgraph_stack_cachep) > + return -ENOMEM; > + } > + > if (!fgraph_initialized) { > ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "fgraph:online", > fgraph_cpu_init, NULL); > -- > 2.45.2 > -- Masami Hiramatsu (Google)