This fixes two deadlocks: 1.pcpu_alloc_mutex involved one as pointed by syzbot[1] 2.recursion deadlock.
The root cause is that we hold the bc lock during alloc_percpu, fix it by following the pattern used by __btree_node_mem_alloc(). [1] https://lore.kernel.org/all/[email protected]/T/ Reported-by: [email protected] Tested-by: [email protected] Signed-off-by: Alan Huang <[email protected]> --- fs/bcachefs/btree_cache.c | 9 +++++---- fs/bcachefs/btree_key_cache.c | 2 +- fs/bcachefs/btree_locking.c | 5 +++-- fs/bcachefs/btree_locking.h | 2 +- fs/bcachefs/six.c | 5 +++-- fs/bcachefs/six.h | 7 ++++--- 6 files changed, 17 insertions(+), 13 deletions(-) diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c index ca755e8d1a37..1ec1f90e0eb3 100644 --- a/fs/bcachefs/btree_cache.c +++ b/fs/bcachefs/btree_cache.c @@ -203,7 +203,7 @@ struct btree *__bch2_btree_node_mem_alloc(struct bch_fs *c) return NULL; } - bch2_btree_lock_init(&b->c, 0); + bch2_btree_lock_init(&b->c, 0, GFP_KERNEL); __bch2_btree_node_to_freelist(bc, b); return b; @@ -795,17 +795,18 @@ struct btree *bch2_btree_node_mem_alloc(struct btree_trans *trans, bool pcpu_rea } b = __btree_node_mem_alloc(c, GFP_NOWAIT|__GFP_NOWARN); - if (!b) { + if (b) { + bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0, GFP_NOWAIT); + } else { mutex_unlock(&bc->lock); bch2_trans_unlock(trans); b = __btree_node_mem_alloc(c, GFP_KERNEL); if (!b) goto err; + bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0, GFP_KERNEL); mutex_lock(&bc->lock); } - bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0); - BUG_ON(!six_trylock_intent(&b->c.lock)); BUG_ON(!six_trylock_write(&b->c.lock)); diff --git a/fs/bcachefs/btree_key_cache.c b/fs/bcachefs/btree_key_cache.c index 1821f40c161a..edce59433375 100644 --- a/fs/bcachefs/btree_key_cache.c +++ b/fs/bcachefs/btree_key_cache.c @@ -156,7 +156,7 @@ bkey_cached_alloc(struct btree_trans *trans, struct btree_path *path, unsigned k } if (ck) { - bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0); + bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0, GFP_KERNEL); ck->c.cached = true; goto lock; } diff --git a/fs/bcachefs/btree_locking.c b/fs/bcachefs/btree_locking.c index 10b805a60f52..caef65adeae4 100644 --- a/fs/bcachefs/btree_locking.c +++ b/fs/bcachefs/btree_locking.c @@ -7,9 +7,10 @@ static struct lock_class_key bch2_btree_node_lock_key; void bch2_btree_lock_init(struct btree_bkey_cached_common *b, - enum six_lock_init_flags flags) + enum six_lock_init_flags flags, + gfp_t gfp) { - __six_lock_init(&b->lock, "b->c.lock", &bch2_btree_node_lock_key, flags); + __six_lock_init(&b->lock, "b->c.lock", &bch2_btree_node_lock_key, flags, gfp); lockdep_set_notrack_class(&b->lock); } diff --git a/fs/bcachefs/btree_locking.h b/fs/bcachefs/btree_locking.h index b54ef48eb8cc..b33ab7af8440 100644 --- a/fs/bcachefs/btree_locking.h +++ b/fs/bcachefs/btree_locking.h @@ -13,7 +13,7 @@ #include "btree_iter.h" #include "six.h" -void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags); +void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags, gfp_t gfp); void bch2_trans_unlock_noassert(struct btree_trans *); void bch2_trans_unlock_write(struct btree_trans *); diff --git a/fs/bcachefs/six.c b/fs/bcachefs/six.c index 7e7c66a1e1a6..7c403427fbdb 100644 --- a/fs/bcachefs/six.c +++ b/fs/bcachefs/six.c @@ -850,7 +850,8 @@ void six_lock_exit(struct six_lock *lock) EXPORT_SYMBOL_GPL(six_lock_exit); void __six_lock_init(struct six_lock *lock, const char *name, - struct lock_class_key *key, enum six_lock_init_flags flags) + struct lock_class_key *key, enum six_lock_init_flags flags, + gfp_t gfp) { atomic_set(&lock->state, 0); raw_spin_lock_init(&lock->wait_lock); @@ -873,7 +874,7 @@ void __six_lock_init(struct six_lock *lock, const char *name, * failure if they wish by checking lock->readers, but generally * will not want to treat it as an error. */ - lock->readers = alloc_percpu(unsigned); + lock->readers = alloc_percpu_gfp(unsigned, gfp); } #endif } diff --git a/fs/bcachefs/six.h b/fs/bcachefs/six.h index c142e06b7a3a..59b851cf8bac 100644 --- a/fs/bcachefs/six.h +++ b/fs/bcachefs/six.h @@ -164,18 +164,19 @@ enum six_lock_init_flags { }; void __six_lock_init(struct six_lock *lock, const char *name, - struct lock_class_key *key, enum six_lock_init_flags flags); + struct lock_class_key *key, enum six_lock_init_flags flags, + gfp_t gfp); /** * six_lock_init - initialize a six lock * @lock: lock to initialize * @flags: optional flags, i.e. SIX_LOCK_INIT_PCPU */ -#define six_lock_init(lock, flags) \ +#define six_lock_init(lock, flags, gfp) \ do { \ static struct lock_class_key __key; \ \ - __six_lock_init((lock), #lock, &__key, flags); \ + __six_lock_init((lock), #lock, &__key, flags, gfp); \ } while (0) /** -- 2.48.1
