Comparing config changes recent kernels

I posted a few times recently, Rodney has reported kernel panic with EasyPup 2.5.1, but 2.5 worked. With EasyOS, latest that worked is 2.4.1.

I have made a table comparing the configuration differences between the kernels in EasyOS 2.4.1 and 2.5.1:

EasyOS 2.4.1, kernel 5.4.59	EasyOS 2.5.1, kernel 5.4.81
CONFIG_LOG_BUF_SHIFT=16 CONFIG_LOG_CPU_MAX_BUF_SHIFT=12	CONFIG_LOG_BUF_SHIFT=17 CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
# CONFIG_VIRTUALIZATION is not set	CONFIG_HAVE_KVM_IRQCHIP=y CONFIG_HAVE_KVM_IRQFD=y CONFIG_HAVE_KVM_IRQ_ROUTING=y CONFIG_HAVE_KVM_EVENTFD=y CONFIG_KVM_MMIO=y CONFIG_KVM_ASYNC_PF=y CONFIG_HAVE_KVM_MSI=y CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT=y CONFIG_KVM_VFIO=y CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT=y CONFIG_KVM_COMPAT=y CONFIG_HAVE_KVM_IRQ_BYPASS=y CONFIG_HAVE_KVM_NO_POLL=y CONFIG_VIRTUALIZATION=y CONFIG_KVM=m CONFIG_KVM_INTEL=m CONFIG_KVM_AMD=m # CONFIG_VHOST_NET is not set # CONFIG_VHOST_CROSS_ENDIAN_LEGACY is not set
	CONFIG_USER_RETURN_NOTIFIER=y
	CONFIG_PREEMPT_NOTIFIERS=y
	CONFIG_SPI_DYNAMIC=y
# CONFIG_VGACON_SOFT_SCROLLBACK is not set
	CONFIG_IRQ_BYPASS_MANAGER=m
# CONFIG_AUFS_HNOTIFY is not set	CONFIG_AUFS_HNOTIFY=y CONFIG_AUFS_HFSNOTIFY=y

CONFIG_USER_RETURN_NOTIFIER

• depends on: CONFIG_HAVE_USER_RETURN_NOTIFIER
• defined in arch/Kconfig
• found in Linux kernels: 2.6.33–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.9, 5.10-rc+HEAD

Provide a kernel-internal notification when a cpu is about to switch to user mode.

BOTH kernels have CONFIG_HAVE_USER_RETURN_NOTIFIER=y
So why is CONFIG_USER_RETURN_NOTIFIER missing from 5.4.59 kernel config?

CONFIG_PREEMPT_NOTIFIERS

• depends on: (none)
• defined in init/Kconfig
• found in Linux kernels: 2.6.24–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.9, 5.10-rc+HEAD

No help
Why is CONFIG_PREEMPT_NOTIFIERS missing from the 5.4.59 kernel config?

CONFIG_SPI_DYNAMIC

• depends on: (none)
• defined in drivers/spi/Kconfig
• found in Linux kernels: 5.9, 5.10-rc+HEAD

No help
Looks like this has been back-ported from 5.9 kernel!
https://lkml.org/lkml/2020/8/24/747

There is nothing that jumps out as the cause of Rodney's kernel panic. Do need to keep the virtualization, besides, Rodney was getting the kernel panic with kernels that did not have virtualization enabled.

I might do a special compile just for Rodney, with CONFIG_USER_RETURN_NOTIFIER, CONFIG_PREEMPT_NOTIFIERS and CONFIG_SPI_DYNAMIC not set.  Jon (scsijon in the forum) suggested to turn on kernel debugging, and then we could analyse the core dump -- a lot of trouble, will just try disabling those options. Reluctant to put much effort into this, as Rodney is the only person reporting kernel panic, and maybe there is something faulty in his PC hardware. 

Tags: easy