Commit 4330a26b authored Aug 06, 2020 by Roman Gushchin Committed by Linus Torvalds Aug 07, 2020

mm: memcg/slab: deprecate memory.kmem.slabinfo



Deprecate memory.kmem.slabinfo.

An empty file will be presented if corresponding config options are
enabled.

The interface is implementation dependent, isn't present in cgroup v2, and
is generally useful only for core mm debugging purposes.  In other words,
it doesn't provide any value for the absolute majority of users.

A drgn-based replacement can be found in
tools/cgroup/memcg_slabinfo.py.  It does support cgroup v1 and v2,
mimics memory.kmem.slabinfo output and also allows to get any
additional information without a need to recompile the kernel.

If a drgn-based solution is too slow for a task, a bpf-based tracing tool
can be used, which can easily keep track of all slab allocations belonging
to a memory cgroup.

Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20200623174037.3951353-11-guro@fb.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f2fe7b09

mm/memcontrol.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -5114,9 +5114,6 @@ static struct cftype mem_cgroup_legacy_files[] = {
		(defined(CONFIG_SLAB) \|\| defined(CONFIG_SLUB_DEBUG))
		{
		.name = "kmem.slabinfo",
		.seq_start = memcg_slab_start,
		.seq_next = memcg_slab_next,
		.seq_stop = memcg_slab_stop,
		.seq_show = memcg_slab_show,
		},
		#endif

mm/slab_common.c

+4 −27

Original line number	Diff line number	Diff line
		@@ -1561,35 +1561,12 @@ void dump_unreclaimable_slab(void)
		}

		#if defined(CONFIG_MEMCG_KMEM)
		void memcg_slab_start(struct seq_file m, loff_t *pos)
		{
		struct mem_cgroup *memcg = mem_cgroup_from_seq(m);

		mutex_lock(&slab_mutex);
		return seq_list_start(&memcg->kmem_caches, *pos);
		}

		void memcg_slab_next(struct seq_file m, void p, loff_t pos)
		{
		struct mem_cgroup *memcg = mem_cgroup_from_seq(m);

		return seq_list_next(p, &memcg->kmem_caches, pos);
		}

		void memcg_slab_stop(struct seq_file m, void p)
		{
		mutex_unlock(&slab_mutex);
		}

		int memcg_slab_show(struct seq_file m, void p)
		{
		struct kmem_cache *s = list_entry(p, struct kmem_cache,
		memcg_params.kmem_caches_node);
		struct mem_cgroup *memcg = mem_cgroup_from_seq(m);

		if (p == memcg->kmem_caches.next)
		print_slabinfo_header(m);
		cache_show(s, m);
		/*
		* Deprecated.
		* Please, take a look at tools/cgroup/slabinfo.py .
		*/
		return 0;
		}
		#endif

Admin message