RE: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned

[Luck, Tony]

> From the walk, it seems we have got the virtual address, can we just send a SIGBUS with it?

If the walk wins the race and the pte for the poisoned page is still valid, then yes.

But we could have:

CPU1                            CPU2
memory_failure sets poison
bit for struct page


rmap finds page in task
on CPU2 and sets PTE
to not-valid-poison

                                memory_failure returns
                                early because struct page
                                already marked as poison

                                walk page tables looking
                                for mapping - don't find it

-Tony