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: 1b26283970 ("block: Keyslot Manager for Inline Encryption")
Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230610061139.212085-1-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Bug: 286427075
(cherry picked from commit 2fb48d88e77f29bf9d278f25bcfe82cf59a0e09b)
(added '#ifdef CONFIG_LOCKDEP' to keep the KMI tooling happy)
Change-Id: I21c0f941a36663c956a5c89324813bbaac0633ef
Signed-off-by: Eric Biggers <ebiggers@google.com>
5e4a5dc820