Commit e83b39d6 authored Nov 15, 2022 by Jan Kara Committed by Andrew Morton Nov 30, 2022

mm: make drop_caches keep reclaiming on all nodes

Currently, drop_caches are reclaiming node-by-node, looping on each node
until reclaim could not make progress.  This can however leave quite some
slab entries (such as filesystem inodes) unreclaimed if objects say on
node 1 keep objects on node 0 pinned.  So move the "loop until no
progress" loop to the node-by-node iteration to retry reclaim also on
other nodes if reclaim on some nodes made progress.  This fixes problem
when drop_caches was not reclaiming lots of otherwise perfectly fine to
reclaim inodes.

Link: https://lkml.kernel.org/r/20221115123255.12559-1-jack@suse.cz


Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: You Zhou <you.zhou@intel.com>
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent d09e8ca6

mm/vmscan.c

+18 −15

Original line number	Diff line number	Diff line
		@@ -1021,31 +1021,34 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
		return freed;
		}

		static void drop_slab_node(int nid)
		static unsigned long drop_slab_node(int nid)
		{
		unsigned long freed;
		int shift = 0;

		do {
		unsigned long freed = 0;
		struct mem_cgroup *memcg = NULL;

		if (fatal_signal_pending(current))
		return;

		freed = 0;
		memcg = mem_cgroup_iter(NULL, NULL, NULL);
		do {
		freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
		} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
		} while ((freed >> shift++) > 1);

		return freed;
		}

		void drop_slab(void)
		{
		int nid;
		int shift = 0;
		unsigned long freed;

		do {
		freed = 0;
		for_each_online_node(nid) {
		if (fatal_signal_pending(current))
		return;

		for_each_online_node(nid)
		drop_slab_node(nid);
		freed += drop_slab_node(nid);
		}
		} while ((freed >> shift++) > 1);
		}

		static int reclaimer_offset(void)