Re: [PATCH v2] x86/fault: Send a SIGBUS to user process always for hwpoison page access.

[Andy Lutomirski]

On Mon, Feb 1, 2021 at 12:17 AM Aili Yao <yaoaili@xxxxxxxxxxxx> wrote:
>
> When one page is already hwpoisoned by AO action, process may not be
> killed, the process mapping this page may make a syscall include this
> page and result to trigger a VM_FAULT_HWPOISON fault, if it's in kernel
> mode it may be fixed by fixup_exception. Current code will just return
> error code to user process.
>
> This is not sufficient, we should send a SIGBUS to the process and log
> the info to console, as we can't trust the process will handle the error
> correctly.

Does this happen when one process gets SIGBUSed due to memory failure
and another process independently hits the poisoned memory?  I'm not
entirely convinced that this is a problem.

In any case, this patch needs rebasing on top of my big fault series
-- as it stands, it's way too difficult to keep track of which paths
even call your new code..  And the various signal paths need to be
consolidated -- we already have three of them, and the last thing we
need is a fourth.