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SubjectRe: [PATCH 1/2] perf: Add munmap callback
On Wed, Oct 24, 2018 at 08:11:15AM -0700, kan.liang@linux.intel.com wrote:
> +void perf_event_munmap(void)
> +{
> + struct perf_cpu_context *cpuctx;
> + unsigned long flags;
> + struct pmu *pmu;
> +
> + local_irq_save(flags);

It is impossible to get here with IRQs already disabled.

> + list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {
> + pmu = cpuctx->ctx.pmu;
> +
> + if (!pmu->munmap)
> + continue;
> +
> + perf_ctx_lock(cpuctx, cpuctx->task_ctx);
> + perf_pmu_disable(pmu);
> +
> + pmu->munmap();
> +
> + perf_pmu_enable(pmu);
> +
> + perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
> + }
> + local_irq_restore(flags);
> +}
> +
> static void perf_event_switch(struct task_struct *task,
> struct task_struct *next_prev, bool sched_in);
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 5f2b2b184c60..61978ad8c480 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2777,6 +2777,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
> /*
> * Remove the vma's, and unmap the actual pages
> */
> + perf_event_munmap();

I think that if you add the munmap hook, you should do it right and at
least do it such that we can solve the other munmap problem.

> detach_vmas_to_be_unmapped(mm, vma, prev, end);
> unmap_region(mm, vma, prev, start, end);
>
> --
> 2.17.1
>

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