The patch titled
Subject: slub: Introduce CONFIG_SLUB_RCU_DEBUG
has been added to the -mm mm-unstable branch. Its filename is
slub-introduce-config_slub_rcu_debug-v8.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/slub-introduce-config_slub_rcu_debug-v8.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jann Horn <jannh@xxxxxxxxxx>
Subject: slub: Introduce CONFIG_SLUB_RCU_DEBUG
Date: Fri, 09 Aug 2024 17:36:56 +0200
- move rcu_barrier() out of locked region (vbabka)
- rearrange code in slab_free_after_rcu_debug (vbabka)
Link: https://lkml.kernel.org/r/20240809-kasan-tsbrcu-v8-2-aef4593f9532@xxxxxxxxxx
Tested-by: syzbot+263726e59eab6b442723@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Acked-by: Marco Elver <elver@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx> (slab)
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: David Sterba <dsterba@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 22 +++++++++++++---------
mm/slub.c | 5 ++---
2 files changed, 15 insertions(+), 12 deletions(-)
--- a/mm/slab_common.c~slub-introduce-config_slub_rcu_debug-v8
+++ a/mm/slab_common.c
@@ -576,15 +576,6 @@ void kmem_cache_destroy(struct kmem_cach
if (unlikely(!s) || !kasan_check_byte(s))
return;
- cpus_read_lock();
- mutex_lock(&slab_mutex);
-
- rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU;
-
- s->refcount--;
- if (s->refcount)
- goto out_unlock;
-
if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) &&
(s->flags & SLAB_TYPESAFE_BY_RCU)) {
/*
@@ -593,10 +584,23 @@ void kmem_cache_destroy(struct kmem_cach
* defer their freeing with call_rcu().
* Wait for such call_rcu() invocations here before actually
* destroying the cache.
+ *
+ * It doesn't matter that we haven't looked at the slab refcount
+ * yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so
+ * the refcount should be 1 here.
*/
rcu_barrier();
}
+ cpus_read_lock();
+ mutex_lock(&slab_mutex);
+
+ rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU;
+
+ s->refcount--;
+ if (s->refcount)
+ goto out_unlock;
+
err = shutdown_cache(s);
WARN(err, "%s %s: Slab cache still has objects when called from %pS",
__func__, s->name, (void *)_RET_IP_);
--- a/mm/slub.c~slub-introduce-config_slub_rcu_debug-v8
+++ a/mm/slub.c
@@ -4563,9 +4563,8 @@ static void slab_free_after_rcu_debug(st
return;
/* resume freeing */
- if (!slab_free_hook(s, object, slab_want_init_on_free(s), true))
- return;
- do_slab_free(s, slab, object, object, 1, _THIS_IP_);
+ if (slab_free_hook(s, object, slab_want_init_on_free(s), true))
+ do_slab_free(s, slab, object, object, 1, _THIS_IP_);
}
#endif /* CONFIG_SLUB_RCU_DEBUG */
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
mm-fix-harmless-type-confusion-in-lock_vma_under_rcu.patch
kasan-catch-invalid-free-before-slub-reinitializes-the-object.patch
slub-introduce-config_slub_rcu_debug.patch
slub-introduce-config_slub_rcu_debug-v8.patch
