On Thu, 1 Sep 2022 10:35:59 +0200 David Hildenbrand <david@xxxxxxxxxx> 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?
