Hi Andrew,
This patch is worth going to mainline for next merge window.
So could you queue this to your tree?
Thanks,
Naoya Horiguchi
On Fri, Jan 22, 2021 at 01:24:24PM +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.
>
> Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
> Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> Signed-off-by: Aili Yao <yaoaili@xxxxxxxxxxxx>
> ---
> mm/memory-failure.c | 34 +++++++++++++++++++---------------
> 1 file changed, 19 insertions(+), 15 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 5a38e9eade94..3fd483e6c2fb 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -243,9 +243,13 @@ 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 (t == current)
> + ret = force_sig_mceerr(BUS_MCEERR_AR,
> (void __user *)tk->addr, addr_lsb);
> + else
> + /* Signal other processes sharing the page if they have PF_MCE_EARLY set. */
> + ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
> + addr_lsb, t);
> } else {
> /*
> * Don't use force here, it's convenient if the signal
> @@ -440,26 +444,26 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
> * Determine whether a given process is "early kill" process which expects
> * to be signaled when some page under the process is hwpoisoned.
> * Return task_struct of the dedicated thread (main thread unless explicitly
> - * specified) if the process is "early kill," and otherwise returns NULL.
> + * specified) if the process is "early kill" and otherwise returns NULL.
> *
> - * Note that the above is true for Action Optional case, but not for Action
> - * Required case where SIGBUS should sent only to the current thread.
> + * Note that the above is true for Action Optional case. For Action Required
> + * case, it's only meaningful to the current thread which need to be signaled
> + * with SIGBUS, this error is Action Optional for other non current
> + * processes sharing the same error page,if the process is "early kill", the
> + * task_struct of the dedicated thread will also be returned.
> */
> static struct task_struct *task_early_kill(struct task_struct *tsk,
> int force_early)
> {
> if (!tsk->mm)
> return NULL;
> - if (force_early) {
> - /*
> - * Comparing ->mm here because current task might represent
> - * a subthread, while tsk always points to the main thread.
> - */
> - if (tsk->mm == current->mm)
> - return current;
> - else
> - return NULL;
> - }
> + /*
> + * Comparing ->mm here because current task might represent
> + * a subthread, while tsk always points to the main thread.
> + */
> + if (force_early && tsk->mm == current->mm)
> + return current;
> +
> return find_early_kill_thread(tsk);
> }
>
> --
> 2.25.1
>
