On Fri, May 31, 2013 at 11:38:59AM -0700, Dave Hansen wrote: > > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Our goal here is to eventually reduce the number of repetitive > acquire/release operations on mapping->tree_lock. > > Logically, this patch has two steps: > 1. rename __remove_mapping() to lock_remove_mapping() since > "__" usually means "this us the unlocked version. > 2. Recreate __remove_mapping() to _be_ the lock_remove_mapping() > but without the locks. > > I think this actually makes the code flow around the locking > _much_ more straighforward since the locking just becomes: > > spin_lock_irq(&mapping->tree_lock); > ret = __remove_mapping(mapping, page); > spin_unlock_irq(&mapping->tree_lock); > > One non-obvious part of this patch: the > > freepage = mapping->a_ops->freepage; > > used to happen under the mapping->tree_lock, but this patch > moves it to outside of the lock. All of the other > a_ops->freepage users do it outside the lock, and we only > assign it when we create inodes, so that makes it safe. > > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > Acked-by: Mel Gorman <mgorman@xxxxxxx> Reviewed-by: Minchan Kin <minchan@xxxxxxxxxx> Just a nitpick below. > > --- > > linux.git-davehans/mm/vmscan.c | 43 ++++++++++++++++++++++++----------------- > 1 file changed, 26 insertions(+), 17 deletions(-) > > diff -puN mm/vmscan.c~make-remove-mapping-without-locks mm/vmscan.c > --- linux.git/mm/vmscan.c~make-remove-mapping-without-locks 2013-05-30 16:07:51.210104924 -0700 > +++ linux.git-davehans/mm/vmscan.c 2013-05-30 16:07:51.214105100 -0700 > @@ -450,12 +450,12 @@ static pageout_t pageout(struct page *pa > * Same as remove_mapping, but if the page is removed from the mapping, it > * gets returned with a refcount of 0. > */ > -static int __remove_mapping(struct address_space *mapping, struct page *page) > +static int __remove_mapping(struct address_space *mapping, > + struct page *page) Unnecessary change. -- Kind regards, Minchan Kim -- 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>