On Sun, 1 Apr 2018 22:35:06 -0400 jglisse@xxxxxxxxxx wrote: > From: Ralph Campbell <rcampbell@xxxxxxxxxx> > > Use of pte_write(pte) is only valid for present pte, the common code > which set the migration entry can be reach for both valid present > pte and special swap entry (for device memory). Fix the code to use > the mpfn value which properly handle both cases. > > On x86 this did not have any bad side effect because pte write bit > is below PAGE_BIT_GLOBAL and thus special swap entry have it set to > 0 which in turn means we were always creating read only special > migration entry. Does this mean that the patch only affects behaviour of non-x86 systems? > So once migration did finish we always write protected the CPU page > table entry (moreover this is only an issue when migrating from device > memory to system memory). End effect is that CPU write access would > fault again and restore write permission. That sounds a bit serious. Was a -stable backport considered?
