Pull printk fix from Petr Mladek: - Prevent softlockup by restoring IRQs in atomic flush after each record * tag 'printk-for-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/nbcon: Restore IRQ in atomic flush after each emitted record
The commit d5d399efff6577 ("printk/nbcon: Release nbcon consoles ownership
in atomic flush after each emitted record") prevented stall of a CPU
which lost nbcon console ownership because another CPU entered
an emergency flush.
But there is still the problem that the CPU doing the emergency flush
might cause a stall on its own.
Let's go even further and restore IRQ in the atomic flush after
each emitted record.
It is not a complete solution. The interrupts and/or scheduling might
still be blocked when the emergency atomic flush was called with
IRQs and/or scheduling disabled. But it should remove the following
lockup:
mlx5_core 0000:03:00.0: Shutdown was called
kvm: exiting hardware virtualization
arm-smmu-v3 arm-smmu-v3.10.auto: CMD_SYNC timeout at 0x00000103 [hwprod 0x00000104, hwcons 0x00000102]
smp: csd: Detected non-responsive CSD lock (#1) on CPU#4, waiting 5000000032 ns for CPU#00 do_nothing (kernel/smp.c:1057)
smp: csd: CSD lock (#1) unresponsive.
[...]
Call trace:
pl011_console_write_atomic (./arch/arm64/include/asm/vdso/processor.h:12 drivers/tty/serial/amba-pl011.c:2540) (P)
nbcon_emit_next_record (kernel/printk/nbcon.c:1049)
__nbcon_atomic_flush_pending_con (kernel/printk/nbcon.c:1517)
__nbcon_atomic_flush_pending.llvm.15488114865160659019 (./arch/arm64/include/asm/alternative-macros.h:254 ./arch/arm64/include/asm/cpufeature.h:808 ./arch/arm64/include/asm/irqflags.h:192 kernel/printk/nbcon.c:1562 kernel/printk/nbcon.c:1612)
nbcon_atomic_flush_pending (kernel/printk/nbcon.c:1629)
printk_kthreads_shutdown (kernel/printk/printk.c:?)
syscore_shutdown (drivers/base/syscore.c:120)
kernel_kexec (kernel/kexec_core.c:1045)
__arm64_sys_reboot (kernel/reboot.c:794 kernel/reboot.c:722 kernel/reboot.c:722)
invoke_syscall (arch/arm64/kernel/syscall.c:50)
el0_svc_common.llvm.14158405452757855239 (arch/arm64/kernel/syscall.c:?)
do_el0_svc (arch/arm64/kernel/syscall.c:152)
el0_svc (./arch/arm64/include/asm/alternative-macros.h:254 ./arch/arm64/include/asm/cpufeature.h:808 ./arch/arm64/include/asm/irqflags.h:73 arch/arm64/kernel/entry-common.c:169 arch/arm64/kernel/entry-common.c:182 arch/arm64/kernel/entry-common.c:749)
el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:820)
el0t_64_sync (arch/arm64/kernel/entry.S:600)
In this case, nbcon_atomic_flush_pending() is called from
printk_kthreads_shutdown() with IRQs and scheduling enabled.
Note that __nbcon_atomic_flush_pending_con() is directly called also from
nbcon_device_release() where the disabled IRQs might break PREEMPT_RT
guarantees. But the atomic flush is called only in emergency or panic
situations where the latencies are irrelevant anyway.
An ultimate solution would be a touching of watchdogs. But it would hide
all problems. Let's do it later when anyone reports a stall which does
not have a better solution.
Closes: https://lore.kernel.org/r/sqwajvt7utnt463tzxgwu2yctyn5m6bjwrslsnupfexeml6hkd@v6sqmpbu3vvu
Tested-by: Breno Leitao <leitao@debian.org>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
Link: https://patch.msgid.link/20251212124520.244483-1-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Pull SoC driver updates from Arnd Bergmann:
"This is the first half of the driver changes:
- A treewide interface change to the "syscore" operations for power
management, as a preparation for future Tegra specific changes
- Reset controller updates with added drivers for LAN969x, eic770 and
RZ/G3S SoCs
- Protection of system controller registers on Renesas and Google
SoCs, to prevent trivially triggering a system crash from e.g.
debugfs access
- soc_device identification updates on Nvidia, Exynos and Mediatek
- debugfs support in the ST STM32 firewall driver
- Minor updates for SoC drivers on AMD/Xilinx, Renesas, Allwinner, TI
- Cleanups for memory controller support on Nvidia and Renesas"
* tag 'soc-drivers-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (114 commits)
memory: tegra186-emc: Fix missing put_bpmp
Documentation: reset: Remove reset_controller_add_lookup()
reset: fix BIT macro reference
reset: rzg2l-usbphy-ctrl: Fix a NULL vs IS_ERR() bug in probe
reset: th1520: Support reset controllers in more subsystems
reset: th1520: Prepare for supporting multiple controllers
dt-bindings: reset: thead,th1520-reset: Add controllers for more subsys
dt-bindings: reset: thead,th1520-reset: Remove non-VO-subsystem resets
reset: remove legacy reset lookup code
clk: davinci: psc: drop unused reset lookup
reset: rzg2l-usbphy-ctrl: Add support for RZ/G3S SoC
reset: rzg2l-usbphy-ctrl: Add support for USB PWRRDY
dt-bindings: reset: renesas,rzg2l-usbphy-ctrl: Document RZ/G3S support
reset: eswin: Add eic7700 reset driver
dt-bindings: reset: eswin: Documentation for eic7700 SoC
reset: sparx5: add LAN969x support
dt-bindings: reset: microchip: Add LAN969x support
soc: rockchip: grf: Add select correct PWM implementation on RK3368
soc/tegra: pmc: Add USB wake events for Tegra234
amba: tegra-ahb: Fix device leak on SMMU enable
...
The macro for_each_console_srcu iterates over all registered consoles. It's implied that all registered consoles have CON_ENABLED flag set, making the check for the flag unnecessary. Call console_is_usable function to fully verify if the given console is usable before calling the ->unblank callback. Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://patch.msgid.link/20251121-printk-cleanup-part2-v2-3-57b8b78647f4@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com>