lkml.org 
[lkml]   [2018]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm, oom: distinguish blockable mode for mmu notifiers
On Fri 24-08-18 13:57:52, Christian König wrote:
> Am 24.08.2018 um 13:52 schrieb Michal Hocko:
> > On Fri 24-08-18 13:43:16, Christian König wrote:
[...]
> > > That won't work like this there might be multiple
> > > invalidate_range_start()/invalidate_range_end() pairs open at the same time.
> > > E.g. the lock might be taken recursively and that is illegal for a
> > > rw_semaphore.
> > I am not sure I follow. Are you saying that one invalidate_range might
> > trigger another one from the same path?
>
> No, but what can happen is:
>
> invalidate_range_start(A,B);
> invalidate_range_start(C,D);
> ...
> invalidate_range_end(C,D);
> invalidate_range_end(A,B);
>
> Grabbing the read lock twice would be illegal in this case.

I am sorry but I still do not follow. What is the context the two are
called from? Can you give me an example. I simply do not see it in the
code, mostly because I am not familiar with it.
--
Michal Hocko
SUSE Labs

\
 
 \ /
  Last update: 2018-08-24 14:04    [W:0.048 / U:1.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site