linux-kernel - Re: [RFC][PATCH] kprobes: Remove kprobe::fault

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Message-ID: <20210210190918.GA2208287@infradead.org>
Date:   Wed, 10 Feb 2021 19:09:18 +0000
From:   Christoph Hellwig <hch@...radead.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yonghong Song <yhs@...com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [RFC][PATCH] kprobes: Remove kprobe::fault_handler

On Wed, Feb 10, 2021 at 02:57:03PM +0100, Peter Zijlstra wrote:
> 
> Somewhat related.. I had this pending.
> 
> ---
> Subject: kprobes: Remove kprobe::fault_handler
> From: Peter Zijlstra <peterz@...radead.org>
> Date: Tue Feb 2 10:43:41 CET 2021
> 
> The reason for kprobe::fault_handler(), as given by their comment:
> 
>  * We come here because instructions in the pre/post
>  * handler caused the page_fault, this could happen
>  * if handler tries to access user space by
>  * copy_from_user(), get_user() etc. Let the
>  * user-specified handler try to fix it first.
> 
> If just plain bad. Those other handlers are ran from non-preemptible
> context and had better use _nofault() functions. Also, there is no
> upstream usage of this.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Looks good,

Reviewed-by: Christoph Hellwig <hch@....de>