lkml.org 
[lkml]   [2008]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: preempt bug in set_pmd_pfn?
On Wed, 5 Mar 2008, Jeremy Fitzhardinge wrote:
>
> If a thread goes from processor A -> B -> A, where A is first preempted
> between a pagetable update and a tlb flush, then the second time the thread
> runs on A may run with a stale tlb (if in the meantime A has either been idle
> or only running kernel threads).

Right, thanks, because __flush_tlb_one opts out of the full active_mm
checking which goes on for userspace mms (which covers, for example,
the case of preemption before dup_mmap's flush_tlb_mm).

But is there actually a case where there's a problem? So far as I can see,
set_pmd_pfn is there solely for discontig_32's __init remap_numa_kva; and
set_pte_pfn is there solely for set_fixmap, which operates on a per-cpu
area of pagetable, which would already be in bigger trouble if preemption
to another cpu were possible.

Hugh


\
 
 \ /
  Last update: 2008-03-05 18:43    [W:0.080 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site