Re: [PATCH v3 05/12] arm64: smp: Defer RCU registration during secondary CPU bringup

Jinjie,

On Tue, Jul 07, 2026 at 11:02:32AM +0800, Jinjie Ruan wrote:

On 7/7/2026 1:39 AM, Will Deacon wrote:

quoted

ce3d31ad3cac ("arm64/smp: Move rcu_cpu_starting() earlier") was to
handle the useless print in cpuinfo_detect_icache_policy(), but I've
decided just to remove that one. So I think the remaining prints we have
to worry about in this early boot code are from error paths in the
CPU feature detection logic (check_local_cpu_capabilities()).

Given that those error paths should all be fatal, perhaps we could
rework cpu_die_early() and cpu_panic_kernel() as macros that take a
string argument and either call printk_deferred() (similarly to what you
suggested in a previous version of your series [1]) or do the
lockdep_off() there before a pr_crit().

What do you think?

That is an excellent point. Reworking cpu_die_early() and
cpu_panic_kernel() to uniformly use printk_deferred() based on the
specific error type or the string argument is a much cleaner approach.

This makes perfect sense because these paths are inherently fatal, and
switching to deferred printing avoids the risky lock-taking and RCU
runtime constraints during early boot entirely. It cleanly resolves the
diagnostic noise without broadly blinding lockdep or hiding potential
locking issues down the line.

I fully agree with this approach.

It's great that your AI chatbot thinks this is fantastic, but what do
_you_ think? I'm much more interested in your opinion, as you have
already spent time thinking about this.

Will