1 Sep
2022
1 Sep
'22
10:35 p.m.
On Thu, 1 Sep 2022 10:35:59 +0200 David Hildenbrand david@redhat.com wrote:
The possible issues due to reordering are of theoretical nature so far and attempts to reproduce the race failed.
Especially the "no PTE change" case isn't the common case, because we'd need an exclusive anonymous page that's mapped R/O and the PTE is clean in KSM code -- and using KSM with page pinning isn't extremely common. Further, the clear+TLB flush we used for now implies a memory barrier. So the problematic missing part should be the missing memory barrier after pinning but before checking if the PTE changed.
Obscure bug, large and tricky patch. Is a -stable backport really justifiable?