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SubjectRe: [PATCH mm v2 30/33] kasan: implement stack ring for tag-based modes
On Thu, Jul 21, 2022 at 10:41 PM Andrey Konovalov <andreyknvl@gmail.com> wrote:
>
> On Tue, Jul 19, 2022 at 1:41 PM Marco Elver <elver@google.com> wrote:
> >
> > > + for (u64 i = pos - 1; i != pos - 1 - KASAN_STACK_RING_SIZE; i--) {
> > > + if (alloc_found && free_found)
> > > + break;
> > > +
> > > + entry = &stack_ring.entries[i % KASAN_STACK_RING_SIZE];
> > > +
> > > + /* Paired with smp_store_release() in save_stack_info(). */
> > > + ptr = (void *)smp_load_acquire(&entry->ptr);
> > > +
> > > + if (kasan_reset_tag(ptr) != info->object ||
> > > + get_tag(ptr) != get_tag(info->access_addr))
> > > + continue;
> > > +
> > > + pid = READ_ONCE(entry->pid);
> > > + stack = READ_ONCE(entry->stack);
> > > + is_free = READ_ONCE(entry->is_free);
> > > +
> > > + /* Try detecting if the entry was changed while being read. */
> > > + smp_mb();
> > > + if (ptr != (void *)READ_ONCE(entry->ptr))
> > > + continue;
> >
> > I thought the re-validation is no longer needed because of the rwlock
> > protection?
>
> Oh, yes, forgot to remove this. Will either do in v3 if there are more
> things to fix, or will just send a small fix-up patch if the rest of
> the series looks good.
>
> > The rest looks fine now.
>
> Thank you, Marco!

Hi Marco,

I'm thinking of sending a v3.

Does your "The rest looks fine now" comment refer only to this patch
or to the whole series? If it's the former, could you PTAL at the
other patches?

Thanks!

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