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SubjectRe: [PATCH V3 01/13] perf/core, x86: Add PERF_SAMPLE_DATA_PAGE_SIZE
On Thu, 31 Jan 2019, Liang, Kan wrote:
> > > +u64 perf_get_page_size(u64 virt)
> > > +{
> > > + unsigned long flags;
> > > + unsigned int level;
> > > + pte_t *pte;
> > > +
> > > + if (!virt)
> > > + return 0;
> > > +
> > > + /*
> > > + * Interrupts are disabled, so it prevents any tear down
> > > + * of the page tables.
> > > + * See the comment near struct mmu_table_batch.
> > > + */
> > > + local_irq_save(flags);
> > > + if (virt >= TASK_SIZE)
> > > + pte = lookup_address(virt, &level);
> > > + else {
> > > + if (current->mm)
> > > + pte = lookup_address_in_pgd(pgd_offset(current->mm,
> > > virt),
> > > + virt, &level);
> >
> > Aside from all the missin {}, I'm fairly sure this is broken since this
> > happens from NMI context. This can interrupt switch_mm() and things like
> > use_temporary_mm().
> >
> > Also; why does this live in the x86 code and not in the generic code?
> >
>
> This is x86 implementation.
> In generic code, there is a __weak function. I'll make it clear in the change
> log in v4.

No, instead of hiding it in the changelog, split the patch into two:

#1 Adding the core stuff including the weak function

#2 Adding the x86 implementation.

Thanks,

tglx

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