On Wed, Jan 20, 2021 at 04:24:22PM +0800, Aili Yao wrote:
> When a memory uncorrected error is triggered by process who accessed
> the address with error, It's Action Required Case for only current
> process which triggered this; This Action Required case means Action
> optional to other process who share the same page. Usually killing
> current process will be sufficient, other processes sharing the same
> page will get be signaled when they really touch the poisoned page.
>
> But there is another scenario that other processes
> sharing the same page want to be signaled early with PF_MCE_EARLY set,
> In this case, we should get them into kill list and signal
> BUS_MCEERR_AO to them.
>
> So in this patch, task_early_kill will check current process if
> force_early is set, and if not current,the code will fallback to
> find_early_kill_thread() to check if there is PF_MCE_EARLY process
> who cares the error.
>
> In kill_proc(), BUS_MCEERR_AR is only send to current, other processes in
> kill list will be signaled with BUS_MCEERR_AO.
>
> Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> Signed-off-by: Aili Yao <yaoaili@xxxxxxxxxxxx>
Looks good to me, a few nits below.
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> @@ -243,9 +243,12 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
> pfn, t->comm, t->pid);
>
> if (flags & MF_ACTION_REQUIRED) {
> - WARN_ON_ONCE(t != current);
> - ret = force_sig_mceerr(BUS_MCEERR_AR,
> + if (tk->tsk == current)
You can re-use "t" here.
> + ret = force_sig_mceerr(BUS_MCEERR_AR,
> (void __user *)tk->addr, addr_lsb);
> + else
> + ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
> + addr_lsb, t);
I would place a brief comment above explaining why we are sending BUS_MCEER_AO
to non-current tasks.
E.g: "Signal other processes sharing the page if they have PF_MCE_EARLY set"
> @@ -457,8 +463,6 @@ static struct task_struct *task_early_kill(struct task_struct *tsk,
> */
> if (tsk->mm == current->mm)
> return current;
> - else
> - return NULL;
if (force_early && task->mm == current->mm)
return current;
--
Oscar Salvador
SUSE L3
