On Mon, 03 Mar 2014 18:42:33 -0800 Davidlohr Bueso <davidlohr@xxxxxx> wrote: > On Mon, 2014-03-03 at 17:23 -0800, Andrew Morton wrote: > > On Mon, 03 Mar 2014 16:59:38 -0800 Davidlohr Bueso <davidlohr@xxxxxx> 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. Confused. If the threads share mm->mmap_sem then they share mm and the test will always be false? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>