linux-kernel - Re: [PATCH 19/29] csky: mm: abort uaccess retries upon fatal signal

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Message-ID: <20210121114233.GC48431@C02TD0UTHF1T.local>
Date:   Thu, 21 Jan 2021 11:42:33 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     guoren@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-csky@...r.kernel.org,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH 19/29] csky: mm: abort uaccess retries upon fatal signal

On Thu, Jan 21, 2021 at 02:53:39PM +0800, guoren@...nel.org wrote:
> From: Guo Ren <guoren@...ux.alibaba.com>
> 
> Pick up the patch from the 'Link' made by Mark Rutland. Keep the
> same with x86, arm, arm64, arc, sh, power.
> 
> Link: https://lore.kernel.org/linux-arm-kernel/1499782763-31418-1-git-send-email-mark.rutland@arm.com/
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Cc: Mark Rutland <mark.rutland@....com>
> ---
>  arch/csky/mm/fault.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
> index c7b67976bac4..1482de56f4f7 100644
> --- a/arch/csky/mm/fault.c
> +++ b/arch/csky/mm/fault.c
> @@ -279,8 +279,11 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
>  	 * signal first. We do not need to release the mmap_lock because it
>  	 * would already be released in __lock_page_or_retry in mm/filemap.c.
>  	 */
> -	if (fault_signal_pending(fault, regs))
> +	if (fault_signal_pending(fault, regs)) {
> +		if (!user_mode(regs))
> +			no_context(regs, addr);
>  		return;
> +	}

FWIW, this looks right to me -- I assumed you've tested with the
test-case in the linked email?

It looks like a number of other architectures are still broken here. :/

I'll go and poke them...

Thanks,
Mark.
  
>  	if (unlikely((fault & VM_FAULT_RETRY) && (flags & FAULT_FLAG_ALLOW_RETRY))) {
>  		flags |= FAULT_FLAG_TRIED;
> -- 
> 2.17.1
>