On Wed, May 22, 2024 at 05:46:09PM -0400, Peter Xu wrote:
> > Now, ProcessB still has the page mapped, so upon re-accessing it,
> > it will trigger a new MCE event. memory-failure code will see that this
>
> The question is why accessing that hwpoison entry from ProcB triggers an
> MCE. Logically that's a swap entry and it should generate a page fault
> rather than MCE. Then in the pgfault hanlder we don't need that encoded
> pfn as we have vmf->address.
It would be a swap entry if we reach try_to_umap_one() without trouble.
Then we have the code that converts it:
...
if (PageHWPoison(p))
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
set_{huge_}pte_at
...
But maybe we could only do that for ProcA, while ProcB failed to do that,
which means that for ProcA that is a hwpoisoned-swap-entry, but ProcB still
has this page mapped as usual, so if ProcB re-access it, that will not
trigger a fault (because the page is still mapped in its pagetables).
--
Oscar Salvador
SUSE Labs
