mm/list_lru.c: use list_lru_walk_one() in list_lru_walk_node()

Patch series "mm/list_lru: Add list_lru_shrink_walk_irq() and a user".

This series removes the local_irq_disable() around
list_lru_shrink_walk() (as used by mm/workingset) by adding
list_lru_shrink_walk_irq().

Vladimir Davydov preferred this over `irq' argument which I added to
struct list_lru.

The initial post (of this series) received a Reviewed-by tag by Vladimir
Davydov which I added to each patch of the series.  The series applies
on top of akpm's tree which has Kirill's shrink_slab series and does not
clash with it (akpm asked me to wait a week or so and repost it then).

I tested the code paths by triggering the OOM-killer via memory over
commit and lockdep did not complain (nor did I see any warnings).

This patch (of 4):

list_lru_walk_node() invokes __list_lru_walk_one() with -1 as the
memcg_idx parameter.  The same can be achieved by list_lru_walk_one() and
passing NULL as memcg argument which then gets converted into -1.  This is
a preparation step when the spin_lock() function is lifted to the caller
of __list_lru_walk_one().  Invoke list_lru_walk_one() instead
__list_lru_walk_one() when possible.

Link: http://lkml.kernel.org/r/20180716111921.5365-2-bigeasy@linutronix.deSigned-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/list_lru.c

@@ -287,8 +287,8 @@ unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
 	long isolated = 0;
 	int memcg_idx;
 
-	isolated += __list_lru_walk_one(lru, nid, -1, isolate, cb_arg,
-					nr_to_walk);
+	isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
+				      nr_to_walk);
 	if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
 		for_each_memcg_cache_index(memcg_idx) {
 			isolated += __list_lru_walk_one(lru, nid, memcg_idx,