Messages in this thread | | | Date | Thu, 19 Feb 2015 15:09:01 -0800 | Subject | Re: NUMA_BALANCING and Xen PV guest regression in 3.20-rc0 | From | Linus Torvalds <> |
| |
On Thu, Feb 19, 2015 at 5:06 AM, David Vrabel <david.vrabel@citrix.com> wrote: > > The NUMA_BALANCING series beginning with 5d833062139d (mm: numa: do not > dereference pmd outside of the lock during NUMA hinting fault) and > specifically 8a0516ed8b90 (mm: convert p[te|md]_numa users to > p[te|md]_protnone_numa) breaks Xen 64-bit PV guests. > > Any fault on a present userspace mapping (e.g., a write to a read-only > mapping) is being misinterpreted as a NUMA hinting fault and not handled > correctly. All userspace programs end up continuously faulting. > > This is because the hypervisor sets _PAGE_GLOBAL (== _PAGE_PROTNONE) on > all present userspace page table entries.
That's some crazy stuff, but whatever. The patch is clearly good. Applied,
Linus
| |