Re: [PATCH 1/6] ARM: ensure interrupts are enabled in __do_user_fault()

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2026-02-27 15:19:08 [+0000], Russell King (Oracle) wrote:
> __do_user_fault() may be called from fault handling paths where the
> interrupts are enabled or disabled. E.g. do_page_fault() calls this
> with interrupts enabled, whereas do_sect_fault()->do_bad_area()
> will call this with interrupts disabled. Since this is a userspace
> fault, we know that interrupts were enabled in the parent context,
> so call local_irq_enable() here to give a consistent interrupt state.
> 
> This is necessary for force_sig_info() when PREEMPT_RT is enabled.

Reported-by: Yadi.hu <yadi.hu@windriver.com
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>  arch/arm/mm/fault.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
> index ed4330cc3f4e..6c27ebd49093 100644
> --- a/arch/arm/mm/fault.c
> +++ b/arch/arm/mm/fault.c
> @@ -190,7 +190,8 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
>  
>  /*
>   * Something tried to access memory that isn't in our memory map..
> - * User mode accesses just cause a SIGSEGV
> + * User mode accesses just cause a SIGSEGV. Ensure interrupts are enabled
> + * for preempt RT.
          PREEMPT_RT.
>   */
>  static void
>  __do_user_fault(unsigned long addr, unsigned int fsr, unsigned int sig,

Sebastian