From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f45.google.com (mail-oo1-f45.google.com [209.85.161.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 43D6935A93B for ; Mon, 9 Mar 2026 21:27:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773091655; cv=none; b=iBtHLEkHjSGUNP9jkidasH6lAvq0cVocx+aai19q60r/WT5nBLj4FjU7J8ig/SN7dJc8DClY16MUouPIqLfFaYEzfiE1CvVf7PaXeifiZIy8+l1on9H62y8c5Ez0ylFlMEplpDMSYnbWl494P6WR42mRF0xUDHhpFguEWU47yKg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773091655; c=relaxed/simple; bh=6uUkqbS1peCg656T6d9eFVBNAReBUwqE9WarCDhm26M=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=r/olGOsV2jXrKDCxDzfKfFxrciE2gekTAWC4bIFWorO50cW9P2BSqK6XsNfEstWZaWMzyA9VwWqtTpCLuzpmX+hlkeyvspD/a7Hkl9NwEY8xPKlkL0Om4sFsVk6/cmNk6a+dChdENzKSK+i5YzCgXcWKGkTCfmaT8zQ49+qNIzI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=RhOW/IH8; arc=none smtp.client-ip=209.85.161.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RhOW/IH8" Received: by mail-oo1-f45.google.com with SMTP id 006d021491bc7-67bb021cb80so562196eaf.3 for ; Mon, 09 Mar 2026 14:27:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1773091653; x=1773696453; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=4Ig39XgKJvqjYKJDvVYNDNH+8fk8f4kr1nnRK9rVXmY=; b=RhOW/IH8rJlbjiC5bVwGRCpbaoOYCb0zZVStLFN5KVns1CC9n9ZWf3vxZ+92pxiBRa QOvG8WSmj9BmRtN+qtdC2pcszZVXli/7v2z/YzWNC0PCaTchARGhVj1b+9PUaH8e2/CT HO8sz4z/O/L9FcHn2nK2AqaYQeesXREQSV/ccVwFX0ZLA0cIbQsr5XAONa7i2DjGo/+h rRxG5PG9j4dN7pOkj7xVZueXJVJsT9MViBcNL6P6kfZSQXyBskHoCRdAqWl/T3Ev3WNG KG0r70NcK3aT2P8j5MtnSSKgyXmSekF0I91BWscPxT+jU6yTt0uChVJO4cYnnHf9xZww jPSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773091653; x=1773696453; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=4Ig39XgKJvqjYKJDvVYNDNH+8fk8f4kr1nnRK9rVXmY=; b=l5yvLUcyM7pfe6IspiiuTt6QRefo15jP210uvTuImjdFOd/jSaHRxbfVFHQvUqw6NB j2dCHD9jl78jyM5W5Zy++h6KSiPoTDMfDeLxNl8bLNCflgFRqr6C+wMBkl9rWyl3V5Mi /4zAvnihrC/Oyo4+rMIpcx63qSUOHQXSKVynCwzaPuHqz3+KcgyxTG2ju8mHJCoNmo52 BxrTklvcw8Upi1c4s9GHQcCIFZPrwXvtDrZgUbhKnNwGtM3oPzpZSO7S50a6wF1qRAqo +MC+rw9VNM2ycTPDCLV9rh+LrgPohlDJlnkV00yM34f/5RzyHBAE8xaGyeksAz68KSen Qfxw== X-Forwarded-Encrypted: i=1; AJvYcCXW6GGIborZuzjXzSlQ8rquKbkc88oqBKUyF1Mmz6y92C69/baS4jSfZkZs/bY/X/ZoPUamDPLaSH/vWv0Dhp4r9Zc=@vger.kernel.org X-Gm-Message-State: AOJu0Yx83sxog8bOrhn2SbLY4bvlfrr6CXIf3V6+Nfw5tmO39oGOobwX 8G15rkh+wXQjhRqP0gWwbVIsVZr+u+SOD/KOZ+MFKqCE28kHBu/X5Oob X-Gm-Gg: ATEYQzyNTeicKqfJlqd8B6vUnDgX+pIUFsBcLTUKdejlBHD5HJaYPHT4q3b5ebTtmdj SUsOR2V6814GjfmRYuLfKghZ6z2flH0vmxdPVPJwLp9tN5lDwp5/BoHVlm1laeg4XFPuz1XePdU JxJZG9OG3PZKx/tIMLz65HOCojpPAwRuECt3xEu64mPKIV22r/Ox0HfyQE8s+r+Y6grq58wWlZx UozQxmXRaltP85wa9yjZ8OTg4P75knt20rSge9MJ6AiwdIpV2yWZsO7H/6my5k6EYC0YCqJszAn VkcAMiWZMchYGNrepC153Y/LS2+zA1XfdjfzCo+sCAsfvRvmoJ1+DL8aKUpwa+0ccC7vLI5H65c HTK+d+2nIqwI/7+qaU/VWE+I34lvVAo149NpOFMHQjK4NinWxHv0srB97ihLIVpElWQNj82PZiK 99C4Jr2HCc35VFebLP4RhKwc5HqyVdzId6ts9l+hDBjed7mgPDyLO52dfrSP+3Dz6cUxPJTrhHm 5ThhWUAAMb6UdJK2KGtGafpoc2coldzUgXISI1fkHUDrdl0 X-Received: by 2002:a05:6820:229a:b0:67b:b432:5fbe with SMTP id 006d021491bc7-67bb4326165mr2802956eaf.26.1773091653174; Mon, 09 Mar 2026 14:27:33 -0700 (PDT) Received: from localhost.localdomain (108-212-132-20.lightspeed.irvnca.sbcglobal.net. [108.212.132.20]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-67bb3bb67fbsm2639289eaf.15.2026.03.09.14.27.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 14:27:32 -0700 (PDT) From: Wesley Atwell To: rostedt@goodmis.org Cc: mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Wesley Atwell Subject: [PATCH v2 2/2] tracing: drain deferred trigger frees if kthread startup fails Date: Mon, 9 Mar 2026 15:27:02 -0600 Message-Id: <20260309212702.13622-3-atwellwea@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260309212702.13622-1-atwellwea@gmail.com> References: <20260309212702.13622-1-atwellwea@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Boot-time trigger registration can fail before the trigger-data cleanup kthread exists. Deferring those frees until late init is fine, but the post-boot fallback must still drain the deferred list if kthread creation never succeeds. Otherwise, boot-deferred nodes can accumulate on trigger_data_free_list, later frees fall back to synchronously freeing only the current object, and the older queued entries are leaked forever. Keep the deferred boot-time behavior, but when kthread creation fails, drain the whole queued list synchronously. Do the same in the late-init drain path so queued entries are not stranded there either. Fixes: 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event_trigger_data") Signed-off-by: Wesley Atwell --- v2: - Restore the dropped mutex recheck comment - Clarify the synchronous fallback drain path kernel/trace/trace_events_trigger.c | 79 ++++++++++++++++++++++++----- 1 file changed, 66 insertions(+), 13 deletions(-) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index d5230b759a2d..428b46272ac8 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -22,6 +22,39 @@ static struct task_struct *trigger_kthread; static struct llist_head trigger_data_free_list; static DEFINE_MUTEX(trigger_data_kthread_mutex); +static int trigger_kthread_fn(void *ignore); + +static void trigger_start_kthread_locked(void) +{ + lockdep_assert_held(&trigger_data_kthread_mutex); + + if (!trigger_kthread) { + struct task_struct *kthread; + + kthread = kthread_create(trigger_kthread_fn, NULL, + "trigger_data_free"); + if (!IS_ERR(kthread)) + WRITE_ONCE(trigger_kthread, kthread); + } +} + +static void trigger_data_free_queued_locked(void) +{ + struct event_trigger_data *data, *tmp; + struct llist_node *llnodes; + + lockdep_assert_held(&trigger_data_kthread_mutex); + + llnodes = llist_del_all(&trigger_data_free_list); + if (!llnodes) + return; + + tracepoint_synchronize_unregister(); + + llist_for_each_entry_safe(data, tmp, llnodes, llist) + kfree(data); +} + /* Bulk garbage collection of event_trigger_data elements */ static int trigger_kthread_fn(void *ignore) { @@ -56,30 +89,50 @@ void trigger_data_free(struct event_trigger_data *data) if (data->cmd_ops->set_filter) data->cmd_ops->set_filter(NULL, data, NULL); + /* + * Boot-time trigger registration can fail before kthread creation + * works. Keep the deferred-free semantics during boot and let late + * init start the kthread to drain the list. + */ + if (system_state == SYSTEM_BOOTING && !trigger_kthread) { + llist_add(&data->llist, &trigger_data_free_list); + return; + } + if (unlikely(!trigger_kthread)) { guard(mutex)(&trigger_data_kthread_mutex); + + trigger_start_kthread_locked(); /* Check again after taking mutex */ if (!trigger_kthread) { - struct task_struct *kthread; - - kthread = kthread_create(trigger_kthread_fn, NULL, - "trigger_data_free"); - if (!IS_ERR(kthread)) - WRITE_ONCE(trigger_kthread, kthread); + llist_add(&data->llist, &trigger_data_free_list); + /* Drain the queued frees synchronously if startup failed. */ + trigger_data_free_queued_locked(); + return; } } - if (!trigger_kthread) { - /* Do it the slow way */ - tracepoint_synchronize_unregister(); - kfree(data); - return; - } - llist_add(&data->llist, &trigger_data_free_list); wake_up_process(trigger_kthread); } +static int __init trigger_data_free_init(void) +{ + guard(mutex)(&trigger_data_kthread_mutex); + + if (llist_empty(&trigger_data_free_list)) + return 0; + + trigger_start_kthread_locked(); + if (trigger_kthread) + wake_up_process(trigger_kthread); + else + trigger_data_free_queued_locked(); + + return 0; +} +late_initcall(trigger_data_free_init); + static inline void data_ops_trigger(struct event_trigger_data *data, struct trace_buffer *buffer, void *rec, struct ring_buffer_event *event) -- 2.34.1