On Sat, Nov 17, 2012 at 7:24 AM, Rik van Riel <riel@xxxxxxxxxx> wrote: > On 11/17/2012 09:56 AM, Linus Torvalds wrote: >> >> On Sat, Nov 17, 2012 at 6:50 AM, Borislav Petkov <bp@xxxxxxxxx> wrote: >>> >>> I don't know, however, whether it would be prudent to have some sort of >>> a cheap assertion in the code (cheaper than INVLPG %ADDR, although on >>> older cpus we do MOV CR3) just in case. This should be enabled only with >>> DEBUG_VM on, of course... >> >> >> I wonder how we could actually test for it. We'd have to have some >> per-cpu page-fault address check (along with a generation count on the >> mm or similar). I doubt we'd figure out anything that works reliably >> and efficiently and would actually show any problems > > Would it be enough to simply print out a warning if we fault > on the same address twice (or three times) in a row, and then > flush the local TLB? > > I realize this would not just trigger on CPUs that fail to > invalidate TLB entries that cause faults, but also on kernel > paths that cause a page fault to be re-taken... I'm actually curious if the architecture docs/software developer manuals for IA-32 mandate any TLB invalidations on a #PF Is there any official vendor documentation on the subject? And perhaps equally valid, should we trust it if it exists? > ... but then again, don't we want to find those paths and > fix them, anyway? :) > > -- > All rights reversed > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>