Christophe Leroy <christophe.le...@csgroup.eu> writes: > Le 18/05/2020 à 17:19, Rui Salvaterra a écrit : >> Hi again, Christophe, >> >> On Mon, 18 May 2020 at 15:03, Christophe Leroy >> <christophe.le...@csgroup.eu> wrote: >>> >>> Can you try reverting 697ece78f8f749aeea40f2711389901f0974017a ? It may >>> have broken swap. >> >> Yeah, that was a good call. :) Linux 5.7-rc1 with the revert on top >> survives the beating. I'll be happy to test a definitive patch! >> > > Yeah I discovered recently that the way swap is implemented on powerpc > expects RW and other important bits not be one of the 3 least > significant bits (see __pte_to_swp_entry() )
The last 3 bits are there to track the _PAGE_PRESENT right? What is the RW dependency there? Are you suggesting of read/write migration entry? A swap entry should not retain the pte rw bits right? A swap entry is built using swap type + offset. And it should not have a dependency on pte RW bits. Along with type and offset we also should have the ability to mark it as a pte entry and also set not present bits. With that understanding what am I missing here? > > I guess the easiest for the time being is to revert the commit with a > proper explanation of the issue, then one day we'll modify the way > powerpc manages swap. > -aneesh