linux-kernel - [patch] mm, slab: periodically resched in drain

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Date:   Tue, 27 Dec 2022 22:05:48 -0800 (PST)
From:   David Rientjes <rientjes@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>
cc:     Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [patch] mm, slab: periodically resched in drain_freelist()

drain_freelist() can be called with a very large number of slabs to free,
such as for kmem_cache_shrink(), or depending on various settings of the
slab cache when doing periodic reaping.

If there is a potentially long list of slabs to drain, periodically
schedule to ensure we aren't saturating the cpu for too long.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/slab.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/slab.c b/mm/slab.c
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2211,6 +2211,8 @@ static int drain_freelist(struct kmem_cache *cache,
 		raw_spin_unlock_irq(&n->list_lock);
 		slab_destroy(cache, slab);
 		nr_freed++;
+
+		cond_resched();
 	}
 out:
 	return nr_freed;