lkml.org 
[lkml]   [2011]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: mm: convert vma->vm_flags to 64bit
    On Mon, Apr 11, 2011 at 11:33:58PM -0700, Andrew Morton wrote:
    > How the heck did we end up using 32 flags??

    Good question.

    > > @@ -217,7 +217,7 @@ vivt_flush_cache_range(struct vm_area_struct *vma, unsigned long start, unsigned
    > > {
    > > if (cpumask_test_cpu(smp_processor_id(), mm_cpumask(vma->vm_mm)))
    > > __cpuc_flush_user_range(start & PAGE_MASK, PAGE_ALIGN(end),
    > > - vma->vm_flags);
    > > + (unsigned long)vma->vm_flags);
    > > }
    >
    > I'm surprised this change (and similar) are needed?
    >
    > Is it risky? What happens if we add yet another vm_flags bit and
    > __cpuc_flush_user_range() wants to use it? I guess when that happens,
    > __cpuc_flush_user_range() needs to be changed to take a ull.

    The truncation is fine provided VM_EXEC is within the least significant
    word. If it isn't, then we'll blow up when the cache handling assembly
    gets parsed by the assembler as the VM_EXEC value will overflow.


    \
     
     \ /
      Last update: 2011-04-12 22:35    [W:0.020 / U:91.056 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site