linux.git/kernel/printk, branch v7.3-rc3

Merge branch 'for-7.4-trivial' into for-linus

2026-09-09T07:52:21+00:00

printk/nbcon: Change nbcon_irq_work to IRQ_WORK_LAZY

2026-09-02T09:28:16+00:00

Change the nbcon_irq_work to be IRQ_WORK_LAZY, thus not raising
an IRQ upon irq_work queuing. The irq_work is then handled on the
next kernel tick. This additional delay is acceptable because
nbcon_irq_work is only responsible for non-emergency deferred
printing, which is delayed anyway. This has the benefit of not
needing to raise an IRQ for each printk() call.

On a side note, the Tegra20 and Tegra30 platforms can hang if an
irq_work IRQ is raised while entering cpuidle states. This problem
was reproducible by calling printk() while entering cpuidle. So
this change also provides a workaround for these platforms (as long
as they are not running tickless).

Link: https://lore.kernel.org/lkml/f3757a75-0ba1-4558-bf57-f19ab7e59a4c@nvidia.com
Fixes: 76f258bf3f2a ("printk: nbcon: Introduce printer kthreads")
Signed-off-by: John Ogness 
Reviewed-by: Sebastian Andrzej Siewior 
Reviewed-by: Petr Mladek 
Tested-by: Jon Hunter 
Link: https://patch.msgid.link/20260901093245.344455-3-john.ogness@linutronix.de
Signed-off-by: Petr Mladek

printk/nbcon: Flush nbcon_irq_work in nbcon_free()

2026-09-02T09:28:12+00:00

Ensure any pending nbcon_irq_work is flushed before allowing the
console to be recycled.

Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Link: https://patch.msgid.link/20260901093245.344455-2-john.ogness@linutronix.de
Signed-off-by: Petr Mladek

printk: Don't WARN on kthread_run failure.

2026-08-24T13:04:11+00:00

Since __kthread_create_on_node() returns -EINTR upon SIGKILL,
we should not use WARN_ON() in order to catch kthread_run() failure.

Reported-by: syzbot+1ebbc20f223b99446034@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1ebbc20f223b99446034
Fixes: 5f53ca3ff83b ("printk: Implement legacy printer kthread for PREEMPT_RT")
Fixes: 76f258bf3f2a ("printk: nbcon: Introduce printer kthreads")
Signed-off-by: Tetsuo Handa 
Reviewed-by: John Ogness 
Reviewed-by: Petr Mladek 
Link: https://patch.msgid.link/76bb4c1c-5d85-4635-b3bb-fc06f292c59e@I-love.SAKURA.ne.jp
Signed-off-by: Petr Mladek

Merge branch 'for-7.3-console-registration-cleanup' into for-linus

2026-08-19T08:00:46+00:00

printk: Handle pre-enabled consoles in the top-level register_console()

2026-07-17T09:19:41+00:00

The function try_enable_preferred_console() currently has the
non-obvious side effect of returning success for consoles that are
already pre-enabled. This obscures the logic flow during console
registration.

Move the check for pre-enabled consoles directly into the top-level
register_console(). This change makes the handling of pre-enabled
consoles explicit and easier to follow.

Furthermore, this separation lays the groundwork for future cleanups
where try_enable_preferred_console() can be restricted to cases where
an entry actually exists in the console_cmdline[] array.

Also it fixes a possible out-of-bound access when the console_cmdline[]
array is full and no console matched. In fact, the check of
c->user_specified did not make much sense. The new console either
matched and was handled in the for-cycle. Or it did not match
and then *c pointed to an unused entry.

Possible behavior change:

try_enable_preferred_console() will newly be called also with
@user_specified parameter set to "false" when it failed with the "true"
variant. But it looks like the right way to do. It will allow to call
newcon->setup() when the console was preferred by some platform
specific code.

Reported-by: Naveen Kumar Chaudhary  # out-of-bound access
Closes: https://lore.kernel.org/r/7sq4tr2nmlz32tvkf6vpsghv6exvqfghsrlvywjcqihzsqqbf7@bspclmti5xg4
Reviewed-by: John Ogness 
Link: https://patch.msgid.link/20260604101459.393162-2-pmladek@suse.com
Signed-off-by: Petr Mladek

printk: Fix possible console use-after-free

2026-07-09T11:33:17+00:00

When emitting a record via legacy printing, it is possible that a handover
to another legacy printing context occurs. When a context has performed a
handover, the console SRCU read lock is released and the pointer to the
console struct might now be invalid. Therefore, after calling
nbcon_legacy_emit_next_record() or console_emit_next_record(), it is
necessary to check if a handover occurred _before_ further @con usage.

Sashiko pointed out that console_flush_one_record() was not doing this.

In console_flush_one_record(), after emitting a record, move the further
usage of @con after the handover check.

Fixes: c158834b223f ("printk: nbcon: Use nbcon consoles in console_flush_all()")
Reported-by: Sashiko 
Closes: https://lore.kernel.org/lkml/20260630170903.099D61F000E9@smtp.kernel.org
Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Link: https://patch.msgid.link/20260703141521.202813-1-john.ogness@linutronix.de
Signed-off-by: Petr Mladek

printk: fix typos in comments

2026-06-02T13:36:06+00:00

Fix spelling/grammatical errors in printk.c and nbcon.c:
- "precation" -> "precautionary"
- "othrewise" -> "otherwise"
- "An usable" -> "A usable"
- "made a progress" -> "made progress"
- "preemtible" -> "preemptible"
- "mechasism" -> "mechanism"
- "ownerhip" -> "ownership"

Signed-off-by: Naveen Kumar Chaudhary 
Link: https://patch.msgid.link/pakfewagyzb7da3yuxnaxdaoma5w4j2c7i3xebmcld3xy4mqs5@zxsx2idpxrdq
Reviewed-by: Petr Mladek 
Signed-off-by: Petr Mladek

Merge branch 'rework/prb-fixes' into for-linus

2026-04-20T11:42:01+00:00

printk: ringbuffer: fix errors in comments

2026-03-31T15:40:23+00:00

The printk ringbuffer implementation is described in the comment as
using three ringbuffers, but the current implementation uses two (desc
and data). Update the comment so it matches the code.

Fix few more known issues in the comments.

Signed-off-by: Loïc Grégoire 
Reviewed-by: John Ogness 
Link: https://patch.msgid.link/20260328021855.53956-1-loicgre@gmail.com
[pmladek@suse.com: Fixed few more issues in the comments by John Ogness.]
Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Signed-off-by: Petr Mladek