Re: [PATCH] tracing: Fix tracing_marker may trigger page fault during preempt_disable

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Fri, 29 Aug 2025 18:13:11 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Fri, 29 Aug 2025 20:53:40 +0100
> Catalin Marinas <catalin.marinas@arm.com> wrote:
> valid user address.
> > 
> > BTW, arm64 also bails out early in do_page_fault() if in_atomic() but I
> > suspect that's not the case here.
> > 
> > Adding Al Viro since since he wrote a large part of uaccess.h.
> > 
> 
> So, __copy_from_user_inatomic() is supposed to be called if
> pagefault_disable() has already been called? If this is the case, can we
> add more comments to this code? I've been using the inatomic() version this
> way in preempt disabled locations since 2016.

Ah, OK. it is internal version... plz ignore my previous mail.

Thanks,

> 
> Looks like it needs to be converted to copy_from_user_nofault().
> 
> Luo, this version of the patch looks legit, no need for a v2.
> 
> I just wanted to figure out why __copy_from_user_inatomic() wasn't atomic.
> If anything, it needs to be better documented.
> 
> -- Steve


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>