Re: [bug report] dead loop in generic_perform_write() //Re: [PATCH v7 07/12] iov_iter: Convert iterate*() to inline funcs

[Linus Torvalds]

On Mon, 4 Mar 2024 at 03:56, David Howells <dhowells@xxxxxxxxxx> wrote:
>
> That said, I wonder if:
>
>         #ifdef copy_mc_to_kernel
>
> should be:
>
>         #ifdef CONFIG_ARCH_HAS_COPY_MC

Hmm. Maybe. We do have that

  #ifdef copy_mc_to_kernel

pattern already in <linux/uaccess.h>, so clearly we've done it both ways.

I personally like the "just test for the thing you are using" model,
which is then why I did it that way, but I don't have hugely strong
opinions on it.

> and whether it's possible to find out dynamically if MCEs can occur at all.

I really wanted to do something like that, and look at the source page
to decide "is this a pmem page that can cause machine checks", but I
didn't find any obvious way to do that.

Improvement suggestions more than welcome.

               Linus