From 49f6ac6f1cde88bab4e530317510d1cf8870e404 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 9 Jun 2023 23:11:39 -0700 Subject: blk-crypto: use dynamic lock class for blk_crypto_profile::lock [ Upstream commit 2fb48d88e77f29bf9d278f25bcfe82cf59a0e09b ] When a device-mapper device is passing through the inline encryption support of an underlying device, calls to blk_crypto_evict_key() take the blk_crypto_profile::lock of the device-mapper device, then take the blk_crypto_profile::lock of the underlying device (nested). This isn't a real deadlock, but it causes a lockdep report because there is only one lock class for all instances of this lock. Lockdep subclasses don't really work here because the hierarchy of block devices is dynamic and could have more than 2 levels. Instead, register a dynamic lock class for each blk_crypto_profile, and associate that with the lock. This avoids false-positive lockdep reports like the following: ============================================ WARNING: possible recursive locking detected 6.4.0-rc5 #2 Not tainted -------------------------------------------- fscryptctl/1421 is trying to acquire lock: ffffff80829ca418 (&profile->lock){++++}-{3:3}, at: __blk_crypto_evict_key+0x44/0x1c0 but task is already holding lock: ffffff8086b68ca8 (&profile->lock){++++}-{3:3}, at: __blk_crypto_evict_key+0xc8/0x1c0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&profile->lock); lock(&profile->lock); *** DEADLOCK *** May be due to missing lock nesting notation Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption") Reported-by: Bart Van Assche Signed-off-by: Eric Biggers Reviewed-by: Bart Van Assche Link: https://lore.kernel.org/r/20230610061139.212085-1-ebiggers@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-crypto-profile.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/blk-crypto-profile.c b/block/blk-crypto-profile.c index 3290c03c9918..aa7fc1436893 100644 --- a/block/blk-crypto-profile.c +++ b/block/blk-crypto-profile.c @@ -79,7 +79,14 @@ int blk_crypto_profile_init(struct blk_crypto_profile *profile, unsigned int slot_hashtable_size; memset(profile, 0, sizeof(*profile)); - init_rwsem(&profile->lock); + + /* + * profile->lock of an underlying device can nest inside profile->lock + * of a device-mapper device, so use a dynamic lock class to avoid + * false-positive lockdep reports. + */ + lockdep_register_key(&profile->lockdep_key); + __init_rwsem(&profile->lock, "&profile->lock", &profile->lockdep_key); if (num_slots == 0) return 0; @@ -89,7 +96,7 @@ int blk_crypto_profile_init(struct blk_crypto_profile *profile, profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]), GFP_KERNEL); if (!profile->slots) - return -ENOMEM; + goto err_destroy; profile->num_slots = num_slots; @@ -441,6 +448,7 @@ void blk_crypto_profile_destroy(struct blk_crypto_profile *profile) { if (!profile) return; + lockdep_unregister_key(&profile->lockdep_key); kvfree(profile->slot_hashtable); kvfree_sensitive(profile->slots, sizeof(profile->slots[0]) * profile->num_slots); -- cgit v1.2.3