From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from devianza.investici.org (devianza.investici.org [198.167.222.108]) (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 25FB74D9914; Tue, 21 Jul 2026 15:14:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.167.222.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784646854; cv=none; b=VWFdANZv8YAmT4GL9FPsxFRnJRehbymkLI4v6cRuaI6OmzYOh6+XHj0Ck3j2oBwy6xzR5RsN5mPUZ3So06ntP258tSZ314Pt6QKXFcYISjBiFxbR2qiziayF+/zl0oW/ysgYHVihApR9YpdaWQtyfWqy7ACtt1nDABpDTeVRe4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784646854; c=relaxed/simple; bh=StdNA1WERZBz3R832dxnd3DmnecPu8RaIVeJcTN9nJM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D4uYCFbxKSHl7romuzDbngUt4LRf3v6oX1Mk4bhhl9EQnMbTfLWMxdDee52YGiXFE1U8R82pn+Kw76JP8CAYrJf3RA0ho4dxt5nfTcpEBevS+Qvn3XL0BtFIN3OGVLXyIQg0KJlZQpLXF1AHoXO55qz6O8EQlvAeqmVjnejFieY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=grrlz.net; spf=pass smtp.mailfrom=grrlz.net; dkim=pass (1024-bit key) header.d=grrlz.net header.i=@grrlz.net header.b=UFNLM+vu; arc=none smtp.client-ip=198.167.222.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=grrlz.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=grrlz.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=grrlz.net header.i=@grrlz.net header.b="UFNLM+vu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=grrlz.net; s=stigmate; t=1784646849; bh=pbKDGyNNyhDV1H5PR4A8c50OlkFbCH78KDfnPB0VA6w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UFNLM+vumosCC9EyEK+PQKYA3EUr1upq2TWPePwN5KH/nfU+TDJjZKakbxvqim6Tr ogeSAoqUrtIBnKZCBVDsjE6iOIopbbttQjh89NqivAhDIAMBTS6UAuTYgvL6+vOncf TQZ7MZ6puX+XljlXxojFfCmlbxHpsua38BRpNvwY= Received: from mx2.investici.org (unknown [127.0.0.1]) by devianza.investici.org (Postfix) with ESMTP id 4h4LWj3LXyz6vNZ; Tue, 21 Jul 2026 15:14:09 +0000 (UTC) Received: by mx2.investici.org (Postfix) id 4h4LWh4sK6z4vyJ; Tue, 21 Jul 2026 15:14:08 +0000 (UTC) From: Bradley Morgan To: akpm@linux-foundation.org Cc: baoquan.he@linux.dev, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, rafael@kernel.org, lenb@kernel.org, pavel@kernel.org, kees@kernel.org, tony.luck@intel.com, gpiccoli@igalia.com, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-pm@vger.kernel.org, Bradley Morgan Subject: [PATCH v2 1/3] reboot: log the task that initiated the reboot Date: Tue, 21 Jul 2026 16:13:56 +0100 Message-ID: <20260721151358.4185467-2-include@grrlz.net> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260721151358.4185467-1-include@grrlz.net> References: <20260721151358.4185467-1-include@grrlz.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When a machine reboots or powers off, the kernel log records what happened but not who asked for it. The reboot syscall throws the caller identity away, and userspace does not reliably record it either: systemd only journals shutdowns that go through logind, anything calling reboot(2) directly (watchdog daemons, container agents, orchestration tooling) leaves no record at all, and the journal is being torn down while the machine goes away, so even the lines that should be written can be lost. The kernel is the only place that always sees the caller, and a kernel log line survives via pstore or a serial console when userspace logs do not. Log the comm and pid of the calling task in the reboot syscall, once the requested command is committed and can no longer fail, e.g: reboot: initiated by systemd-shutdow[1] reboot: Restarting system The existing "Restarting system", "System halted" and "Power down" lines are left untouched, so anything parsing dmesg today keeps working. The two ctrl alt del toggle commands are excluded so init setting the mode does not add a line to dmesg on every boot. Signed-off-by: Bradley Morgan --- include/linux/reboot.h | 1 + kernel/reboot.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/linux/reboot.h b/include/linux/reboot.h index aa08c3bbbf59..3fb8d8533563 100644 --- a/include/linux/reboot.h +++ b/include/linux/reboot.h @@ -172,6 +172,7 @@ extern void kernel_restart(char *cmd); extern void kernel_halt(void); extern void kernel_power_off(void); extern bool kernel_can_power_off(void); +void reboot_log_initiator(void); void ctrl_alt_del(void); diff --git a/kernel/reboot.c b/kernel/reboot.c index bed6967bfa96..3f4534cd5b9c 100644 --- a/kernel/reboot.c +++ b/kernel/reboot.c @@ -717,6 +717,18 @@ EXPORT_SYMBOL_GPL(kernel_power_off); DEFINE_MUTEX(system_transition_mutex); +/* + * Log the task that asked for the transition once the requested + * command is committed and can no longer fail, e.g: + * + * reboot: initiated by systemd-shutdow[1] + * reboot: Restarting system + */ +void reboot_log_initiator(void) +{ + pr_info("initiated by %s[%d]\n", current->comm, task_pid_nr(current)); +} + /* * Reboot system call: for obvious reasons only root may call it, * and even root needs to set up some magic numbers in the registers @@ -764,6 +776,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, mutex_lock(&system_transition_mutex); switch (cmd) { case LINUX_REBOOT_CMD_RESTART: + reboot_log_initiator(); kernel_restart(NULL); break; @@ -776,10 +789,12 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, break; case LINUX_REBOOT_CMD_HALT: + reboot_log_initiator(); kernel_halt(); do_exit(0); case LINUX_REBOOT_CMD_POWER_OFF: + reboot_log_initiator(); kernel_power_off(); do_exit(0); break; @@ -792,6 +807,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, } buffer[sizeof(buffer) - 1] = '\0'; + reboot_log_initiator(); kernel_restart(buffer); break; -- 2.50.1