On 2/26/21 10:56 AM, Steven Rostedt wrote:

On Fri, 26 Feb 2021 10:02:53 +0800
Jacob Wen [off-list ref] wrote:

quoted

Freeing a slab name generally means removing a kernel module.
See the callers of kmem_cache_destroy.

We need to fix some of the trace events that call TP_printk with %pS
to get a symbol of a kernel module that maybe removed later.

No. If the symbol is not found in the kallsyms lookup at the time of
reading the trace, it will act just like a %p and print the address.
Yes, it can change the reading of the trace file form one read to the
next, but it's harmless, and it's been like this since ftrace was
introduced back in 2009.

-- Steve

Removing a kernel module to see if it releases a lot of memory is
helpful to quickly find out the root causes of some issues.

It seems nice to reserve the symbols. I don't have a relevant use case
so it's just my 2 cents.