> On Jul 20, 2018, at 6:22 AM, Joerg Roedel <joro@xxxxxxxxxx> wrote: > > From: Joerg Roedel <jroedel@xxxxxxx> > > The ring-buffer is accessed in the NMI handler, so we better > avoid faulting on it. Sync the vmalloc range with all > page-tables in system to make sure everyone has it mapped. > > This fixes a WARN_ON_ONCE() that can be triggered with PTI > enabled on x86-32: > > WARNING: CPU: 4 PID: 0 at arch/x86/mm/fault.c:320 vmalloc_fault+0x220/0x230 > > This triggers because with PTI enabled on an PAE kernel the > PMDs are no longer shared between the page-tables, so the > vmalloc changes do not propagate automatically. It seems like it would be much more robust to fix the vmalloc_fault() code instead.
