From: Breno Leitao <leitao@debian.org>
To: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Steven Rostedt <rostedt@goodmis.org>,
Ryan Roberts <ryan.roberts@arm.com>,
printk@lists.linux.dev, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH printk 3/6] printk: Evaluate flush policy in nbcon_allow_unsafe_takeover()
Date: Mon, 9 Nov 2026 06:08:40 -0800 [thread overview]
Message-ID: <avHTDeox8nDGLC6Q@gmail.com> (raw)
In-Reply-To: <20261109123127.489676-4-john.ogness@linutronix.de>
On Mon, Nov 09, 2026 at 01:37:20PM +0106, John Ogness wrote:
> @@ -1572,7 +1608,12 @@ static int __nbcon_atomic_flush_pending_con(struct console *con, enum pr_flush_r
> ctxt->console = con;
> ctxt->spinwait_max_us = 2000;
> ctxt->prio = nbcon_get_default_prio();
> - ctxt->allow_unsafe_takeover = nbcon_allow_unsafe_takeover();
> + ctxt->allow_unsafe_takeover = nbcon_allow_unsafe_takeover(con, reason);
Thanks for the series, I've tried it here, and I got:
sysrq: Resetting
------------[ cut here ]------------
WARNING: kernel/printk/nbcon.c:561 at nbcon_context_try_acquire+0x72c/0x790, CPU#0: sh/212
Modules linked in: nbcon_hold(OE+)
CPU: 0 UID: 0 PID: 212 Comm: sh Tainted: G OE 7.4.0-rc1-next-20261105upstream-00006-g4170adac69fb #1 PREEMPT(full)
Hardware name: linux,dummy-virt (DT)
pc : nbcon_context_try_acquire+0x72c/0x790
lr : nbcon_context_try_acquire+0x508/0x790
...
Call trace:
nbcon_context_try_acquire+0x72c/0x790 (P)
__nbcon_atomic_flush_pending_con+0x1c0/0x358
nbcon_atomic_flush_pending+0x224/0x390
printk_trigger_flush+0x50/0x1c8
emergency_restart+0x54/0x98
sysrq_handle_reboot+0x5c/0x88
__handle_sysrq+0x298/0x3c0
write_sysrq_trigger+0x178/0x1d0
proc_reg_write+0x148/0x270
vfs_write+0x1d4/0x7c8
ksys_write+0xbc/0x168
__arm64_sys_write+0x88/0xa8
invoke_syscall+0x74/0x188
do_el0_svc+0x108/0x190
el0_svc+0x60/0x1d8
el0t_64_sync_handler+0x68/0xe0
el0t_64_sync+0x198/0x1a0
That is coming from:
550 static int nbcon_context_try_acquire_hostile(struct nbcon_context *ctxt,
551 struct nbcon_state *cur)
552 {
553 unsigned int cpu = smp_processor_id();
554 struct console *con = ctxt->console;
555 struct nbcon_state new;
556
557 if (!ctxt->allow_unsafe_takeover)
558 return -EPERM;
559
560 /* Ensure caller is allowed to perform unsafe hostile takeovers. */
561 if (WARN_ON_ONCE(ctxt->prio != NBCON_PRIO_PANIC))
562 return -EPERM;
Thanks,
--breno
next prev parent reply other threads:[~2026-11-09 14:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 12:31 [PATCH printk 0/6] Introduce policies for unsafe flushing John Ogness
2026-11-09 12:31 ` [PATCH printk 1/6] printk: Introduce and specify flush reasons John Ogness
2026-11-09 12:31 ` [PATCH printk 2/6] console: Introduce unsafe flush policy flags John Ogness
2026-11-09 12:31 ` [PATCH printk 3/6] printk: Evaluate flush policy in nbcon_allow_unsafe_takeover() John Ogness
2026-11-09 14:08 ` Breno Leitao [this message]
2026-11-09 14:28 ` John Ogness
2026-11-09 12:31 ` [PATCH printk 4/6] printk: Remove nbcon_atomic_flush_unsafe() John Ogness
2026-11-09 12:31 ` [PATCH printk 5/6] printk: Add panic+kexec flush point John Ogness
2026-11-09 12:31 ` [PATCH printk 6/6] netconsole: Always perform unsafe flushing on panic/kdb/restart John Ogness
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