Thread (18 messages) 18 messages, 5 authors, 2025-09-02

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

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2025-09-01 16:01:20
Also in: linux-arm-kernel, lkml

On Fri, 29 Aug 2025 18:13:11 -0400
Steven Rostedt [off-list ref] wrote:
On Fri, 29 Aug 2025 20:53:40 +0100
Catalin Marinas [off-list ref] wrote:
valid user address.
quoted
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) [off-list ref]
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