Re: [PATCHi v2] mm: do not drop unused pages when userfaultd is running

2018-07-02 Thread Christian Borntraeger
On 07/02/2018 11:06 PM, Andrew Morton wrote: > On Mon, 2 Jul 2018 09:50:49 +0200 Christian Borntraeger > wrote: > >> KVM guests on s390 can notify the host of unused pages. This can result >> in pte_unused callbacks to be true for KVM guest memory. >> >> If a page is unused (checked with pte

Re: [PATCHi v2] mm: do not drop unused pages when userfaultd is running

2018-07-02 Thread Andrew Morton
On Mon, 2 Jul 2018 09:50:49 +0200 Christian Borntraeger wrote: > KVM guests on s390 can notify the host of unused pages. This can result > in pte_unused callbacks to be true for KVM guest memory. > > If a page is unused (checked with pte_unused) we might drop this page > instead of paging it.

[PATCHi v2] mm: do not drop unused pages when userfaultd is running

2018-07-02 Thread Christian Borntraeger
KVM guests on s390 can notify the host of unused pages. This can result in pte_unused callbacks to be true for KVM guest memory. If a page is unused (checked with pte_unused) we might drop this page instead of paging it. This can have side-effects on userfaultd, when the page in question was alrea