14 Sep
2023
14 Sep
'23
9:57 p.m.
On Sep 14, 2023, at 8:26 AM, Suren Baghdasaryan surenb@google.com wrote:
- if (!pte_same(ptep_clear_flush(src_vma, src_addr, src_pte),
orig_src_pte))BUG_ON(1);
Just a minor detail regarding these few lines:
Besides the less-than-ideal use of BUG_ON() here, I think that this code assumes that the PTE cannot change at this point. However, as the PTE was still mapped at this point, I think the access and dirty bits can be set.
tl;dr: this appears to be triggerable by userspace.
[ as for the performance of this code, the lack of batching would mean that for multithreaded applications where more than a single page is remapped, performance would suffer ]