Messages in this thread | | | Subject | Re: [PATCH v4] mm: per-thread vma caching | From | Davidlohr Bueso <> | Date | Mon, 03 Mar 2014 18:42:33 -0800 |
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On Mon, 2014-03-03 at 17:23 -0800, Andrew Morton wrote: > On Mon, 03 Mar 2014 16:59:38 -0800 Davidlohr Bueso <davidlohr@hp.com> wrote: > > > > >... > > > > > > > > +static bool vmacache_valid(struct mm_struct *mm) > > > > +{ > > > > + struct task_struct *curr = current; > > > > + > > > > + if (mm != curr->mm) > > > > + return false; > > > > > > What's going on here? Handling a task poking around in someone else's > > > mm? I'm thinking "__access_remote_vm", but I don't know what you were > > > thinking ;) An explanatory comment would be revealing. > > > > I don't understand the doubt here. Seems like a pretty obvious thing to > > check -- yes it's probably unlikely but we certainly don't want to be > > validating the cache on an mm that's not ours... or are you saying it's > > redundant?? > > Well it has to be here for a reason and I'm wondering that that reason > is. If nobody comes here with a foreign mm then let's remove it.
find_vma() can be called by concurrent threads sharing the mm->mmap_sem for reading, thus this check needs to be there.
Thanks, Davidlohr
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