On Tue, Aug 28, 2018 at 10:56 AM, Rik van Riel <riel@xxxxxxxxxxx> wrote: > On Mon, 27 Aug 2018 16:04:16 -0700 > Andy Lutomirski <luto@xxxxxxxxxx> wrote: > >> The 0day bot is still chewing on this, but I've tested it a bit locally >> and it seems to do the right thing. > > Hi Andy, > > the version of the patch below should fix the bug we talked about > in email yesterday. It should automatically cover kernel threads > in lazy TLB mode, because current->mm will be NULL, while the > cpu_tlbstate.loaded_mm should never be NULL. > That's better than mine. I tweaked it a bit and added some debugging, and I got this: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/fixes&id=dd956eba16646fd0b15c3c0741269dfd84452dac I made the loaded_mm handling a little more conservative to make it more obvious that switch_mm_irqs_off() is safe regardless of exactly when it gets called relative to switching current.
