> -----Original Message----- > From: Jan Kara [mailto:jack@xxxxxxx] > Sent: Friday, October 04, 2013 2:33 PM > To: Marciniszyn, Mike > Cc: Jan Kara; LKML; linux-mm@xxxxxxxxx; infinipath; Roland Dreier; linux- > rdma@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 23/26] ib: Convert qib_get_user_pages() to > get_user_pages_unlocked() > > On Fri 04-10-13 13:52:49, Marciniszyn, Mike wrote: > > > Convert qib_get_user_pages() to use get_user_pages_unlocked(). This > > > shortens the section where we hold mmap_sem for writing and also > > > removes the knowledge about get_user_pages() locking from ipath > > > driver. We also fix a bug in testing pinned number of pages when > changing the code. > > > > > > > This patch and the sibling ipath patch will nominally take the mmap_sem > > twice where the old routine only took it once. This is a performance > > issue. > It will take mmap_sem only once during normal operation. Only if > get_user_pages_unlocked() fail, we have to take mmap_sem again to undo > the change of mm->pinned_vm. > > > Is the intent here to deprecate get_user_pages()? > Well, as much as I'd like to, there are really places in mm code which need > to call get_user_pages() while holding mmap_sem to be able to inspect > corresponding vmas etc. So I want to reduce get_user_pages() use as much > as possible but I'm not really hoping in completely removing it. > > > I agree, the old code's lock limit test is broke and needs to be fixed. > > I like the elimination of the silly wrapper routine! > > > > Could the lock limit test be pushed into another version of the > > wrapper so that there is only one set of mmap_sem transactions? > I'm sorry, I don't understand what you mean here... > > Honza > -- > Jan Kara <jack@xxxxxxx> > SUSE Labs, CR -- 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