What does “not syncing” mean in kernel panic?

8
votes

What is meant by "not syncing" in a kernel panic message?

I have read that it means that the kernel successfully synced data to disk, but am not sure.

A typical context would be: "Kernel panic - not syncing - Attempted to kill init!"

2
linuxkernelpanic
I reckon that "syncing" means syncing with your hard disks. – SaltyEgg
It it related to the sync(2) syscall. So not syncing means potential data loss and data corruption. – Basile Starynkevitch

2 Answers

9
votes

not syncing means that the device buffers have not been flushed to the actual devices. We do this to prevent damage to the data.

If we synced on kernel panic, we could cause a lot of trouble to the user. This is because the kernel panic could have happened anywhere and it might cause side-effects to other modules and parts of the kernel.

-3
votes

As per my understanding there are many reasons for kernel panic .I Just writing what i understand here

In the case

Freeing unused kernel memory: 96k init

Kernel panic - not syncing: No init found. Try passing init=option to kernel

common causes is that the root file system image (be it ramdisk, Flash, or NFS root file system) does not have the supporting libraries for the binaries that the kernel is trying to execute .

Which means dynamic loader may be not present in rootfs ,so When kernel try to execute some programs it ll not find required dynamic library in rootfs. Here kernel try to sycn (i.e data to be written to the underlying filesystems) with your hard disk which having rootfs . When kernel sees there is no dynamic loader then kernel ll be panic and complains not syncing.