[lkml]   [2013]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/4] mm/rmap: per anon_vma lock
On Fri, Nov 01, 2013 at 06:07:07PM +0800, Yuanhan Liu wrote:
> > I also want to point out that lately we've seen several changes sent
> > out that relax locking with no accompanying explanation of why the
> > relaxed locking would be safe. Please don't do that - having a lot of
> > performance data is worthless if you can't explain why the new locking
> > is safe.
> Agreed.
> > And I'm not asking to prove a negative ('lack of any possible
> > races') there, but at least in this case one could dig out why the
> > root anon vma locking was introduced and if they think that this
> > reason doesn't apply anymore, explain why...
> It was introduced by commit 2b575eb6(And, BTW, I'm sorry that this commit log
> about bb4aa39676f is wrong)
> commit 2b575eb64f7a9c701fb4bfdb12388ac547f6c2b6
> Author: Peter Zijlstra <>
> Date: Tue May 24 17:12:11 2011 -0700
> mm: convert anon_vma->lock to a mutex
> Straightforward conversion of anon_vma->lock to a mutex.
> As you can see, Peter didn't tell why before. Honestly speaking, that
> was my originaly concern as well. I tried to find some possible races;
> I guess I may miss something.

Bullshit; I didn't change the locking. I only changed the lock primitive
from a spinlock to a mutex. The anon_vma->root->lock is completely
unrelated to this change.

 \ /
  Last update: 2013-11-01 11:41    [W:0.146 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site