6.12-stable review patch. If anyone has any objections, please let me know.
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From: Breno Leitao leitao@debian.org
[ Upstream commit e1d3422c95f003eba241c176adfe593c33e8a8f6 ]
Move the hash table growth check and work scheduling outside the rht lock to prevent a possible circular locking dependency.
The original implementation could trigger a lockdep warning due to a potential deadlock scenario involving nested locks between rhashtable bucket, rq lock, and dsq lock. By relocating the growth check and work scheduling after releasing the rth lock, we break this potential deadlock chain.
This change expands the flexibility of rhashtable by removing restrictive locking that previously limited its use in scheduler and workqueue contexts.
Import to say that this calls rht_grow_above_75(), which reads from struct rhashtable without holding the lock, if this is a problem, we can move the check to the lock, and schedule the workqueue after the lock.
Fixes: f0e1a0643a59 ("sched_ext: Implement BPF extensible scheduler class") Suggested-by: Tejun Heo tj@kernel.org Signed-off-by: Breno Leitao leitao@debian.org
Modified so that atomic_inc is also moved outside of the bucket lock along with the growth above 75% check.
Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org --- lib/rhashtable.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/lib/rhashtable.c b/lib/rhashtable.c index 6c902639728b7..bf956b85455ab 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -584,10 +584,6 @@ static struct bucket_table *rhashtable_insert_one( */ rht_assign_locked(bkt, obj);
- atomic_inc(&ht->nelems); - if (rht_grow_above_75(ht, tbl)) - schedule_work(&ht->run_work); - return NULL; }
@@ -624,6 +620,12 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, data = ERR_CAST(new_tbl);
rht_unlock(tbl, bkt, flags); + + if (PTR_ERR(data) == -ENOENT && !new_tbl) { + atomic_inc(&ht->nelems); + if (rht_grow_above_75(ht, tbl)) + schedule_work(&ht->run_work); + } } } while (!IS_ERR_OR_NULL(new_tbl));