[lkml]   [2014]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] mm: per-thread vma caching
On Fri, Feb 21, 2014 at 12:57 PM, Davidlohr Bueso <> wrote:
> Btw, one concern I had is regarding seqnum overflows... if such
> scenarios should happen we'd end up potentially returning bogus vmas and
> getting bus errors and other sorts of issues. So we'd have to flush the
> caches, but, do we care? I guess on 32bit systems it could be a bit more
> possible to trigger given enough forking.

I guess we should do something like

if (unlikely(!++seqnum))

just to not have to worry about it.

And we can either use a "#ifndef CONFIG_64BIT" to disable it for the
64-bit case (because no, we really don't need to worry about overflow
in 64 bits ;), or just decide that a 32-bit sequence number actually
packs better in the structures, and make it be an "u32" even on 64-bit

It looks like a 32-bit sequence number might pack nicely next to the

unsigned brk_randomized:1;

but I didn't actually go and look at the context there to see what
else is there..


 \ /
  Last update: 2014-02-22 00:01    [W:0.121 / U:1.500 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site