>
> arm64 can take an NMI-like error notification when user-space steps in some corrupt memory. APEI's GHES code will call
> memory_failure_queue() to schedule the recovery work. We then return to user-space, possibly taking the fault again.
>
> Currently the arch code unconditionally signals user-space from this path, so we don't get stuck in this loop, but the affected process never
> benefits from memory_failure()s recovery work. To fix this we need to know the recovery work will run before we get back to user-space.
>
> Increase the priority of the recovery work by scheduling it on the system_highpri_wq, then try to bump the current task off this CPU so that
> the recover work starts immediately.
>
> Reported-by: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Reviewed-by: Punit Agrawal <punit.agrawal@xxxxxxx>
> Tested-by: Tyler Baicar <tbaicar@xxxxxxxxxxxxxx>
> CC: Xie XiuQi <xiexiuqi@xxxxxxxxxx>
> CC: gengdongjiu <gengdongjiu@xxxxxxxxxx>
Tested-by: gengdongjiu <gengdongjiu@xxxxxxxxxx>
> ---
> mm/memory-failure.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 9d142b9b86dc..f0e69d7ac406 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -55,6 +55,7 @@
> #include <linux/hugetlb.h>
> #include <linux/memory_hotplug.h>
> #include <linux/mm_inline.h>
> +#include <linux/preempt.h>
> #include <linux/kfifo.h>
> #include <linux/ratelimit.h>
> #include "internal.h"
> @@ -1333,6 +1334,7 @@ static DEFINE_PER_CPU(struct memory_failure_cpu, memory_failure_cpu);
> */
> void memory_failure_queue(unsigned long pfn, int flags) {
> + int cpu = smp_processor_id();
> struct memory_failure_cpu *mf_cpu;
> unsigned long proc_flags;
> struct memory_failure_entry entry = {
> @@ -1342,11 +1344,14 @@ void memory_failure_queue(unsigned long pfn, int flags)
>
> mf_cpu = &get_cpu_var(memory_failure_cpu);
> spin_lock_irqsave(&mf_cpu->lock, proc_flags);
> - if (kfifo_put(&mf_cpu->fifo, entry))
> - schedule_work_on(smp_processor_id(), &mf_cpu->work);
> - else
> + if (kfifo_put(&mf_cpu->fifo, entry)) {
> + queue_work_on(cpu, system_highpri_wq, &mf_cpu->work);
> + set_tsk_need_resched(current);
> + preempt_set_need_resched();
> + } else {
> pr_err("Memory failure: buffer overflow when queuing memory failure at %#lx\n",
> pfn);
> + }
> spin_unlock_irqrestore(&mf_cpu->lock, proc_flags);
> put_cpu_var(memory_failure_cpu);
> }
> --
> 2.16.2
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