[lkml]   [2011]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch] x86, mm: avoid stale tlb entries by clearing prev mm_cpumask after switching mm
Suresh Siddha <> writes:

> For the prev mm that is handing over the cpu to another mm, clear the cpu
> from the mm_cpumask(prev) after the cr3 is changed.
> Otherwise, clearing the mm_cpumask early will avoid the flush tlb IPI's while
> the cr3 and TLB's are still pointing to the prev mm. And this window can lead
> to the stale (global) TLB entries.
> Marking it for -stable, though we haven't seen any reported failure that
> can be attributed to this.

Would it be safer to add a memory barrier between the load_cr3 and the
cpumask_clear_cpu()? As far as I can see cpumask_clear_cpu doesn't
imply a general one and load_cr3 doesn't either. There's this
__force_order hack in system.h, but I don't think it will enforce
order here.


-- -- Speaking for myself only

 \ /
  Last update: 2011-02-03 02:27    [W:0.062 / U:9.368 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site