This is a note to let you know that I've just added the patch titled rhashtable: Fix walker list corruption to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rhashtable-fix-walker-list-corruption.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Dec 30 19:52:45 PST 2015 From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Date: Wed, 16 Dec 2015 16:45:54 +0800 Subject: rhashtable: Fix walker list corruption From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> [ Upstream commit c6ff5268293ef98e48a99597e765ffc417e39fa5 ] The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- lib/rhashtable.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -506,10 +506,11 @@ int rhashtable_walk_init(struct rhashtab if (!iter->walker) return -ENOMEM; - mutex_lock(&ht->mutex); - iter->walker->tbl = rht_dereference(ht->tbl, ht); + spin_lock(&ht->lock); + iter->walker->tbl = + rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock)); list_add(&iter->walker->list, &iter->walker->tbl->walkers); - mutex_unlock(&ht->mutex); + spin_unlock(&ht->lock); return 0; } @@ -523,10 +524,10 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_init); */ void rhashtable_walk_exit(struct rhashtable_iter *iter) { - mutex_lock(&iter->ht->mutex); + spin_lock(&iter->ht->lock); if (iter->walker->tbl) list_del(&iter->walker->list); - mutex_unlock(&iter->ht->mutex); + spin_unlock(&iter->ht->lock); kfree(iter->walker); } EXPORT_SYMBOL_GPL(rhashtable_walk_exit); @@ -550,14 +551,12 @@ int rhashtable_walk_start(struct rhashta { struct rhashtable *ht = iter->ht; - mutex_lock(&ht->mutex); + rcu_read_lock(); + spin_lock(&ht->lock); if (iter->walker->tbl) list_del(&iter->walker->list); - - rcu_read_lock(); - - mutex_unlock(&ht->mutex); + spin_unlock(&ht->lock); if (!iter->walker->tbl) { iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht); Patches currently in stable-queue which might be from herbert@xxxxxxxxxxxxxxxxxxx are queue-4.1/rhashtable-fix-walker-list-corruption.patch queue-4.1/rhashtable-enforce-minimum-size-on-initial-hash-table.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html