Re: [PATCH v4] block: genhd: don't call probe function with major_names_lock held

On 2021/08/18 23:41, Greg KH wrote:

On Wed, Aug 18, 2021 at 11:34:15PM +0900, Tetsuo Handa wrote:

quoted

On 2021/08/18 22:47, Christoph Hellwig wrote:

quoted

Hi Tetsuo,

I might sound like a broken record, but we need to reduce the locking
complexity, not make it worse and fall down the locking cliff.  I did
send a suggested series this morning, in which you found a bunch of
bugs.  I'd appreciate it if you could use your superior skills to
actually help explain the issue and arrive at a common solution that
actually simplifies things instead of steaming down the locking cliff
full speed.  Thank you very much.

I posted "[PATCH] loop: break loop_ctl_mutex into loop_idr_spinlock and loop_removal_mutex"
which reduces the locking complexity while fixing bugs, but you ignored it. Instead,
you decided to remove cryptoloop module (where userspace doing "modprobe cryptoloop"
will break). That is, you decided not to provide patches which can be backported.

Do not ever worry about backporting patches.  Worry about getting the
changes and code correct, stable work can come afterwards, if needed.

The loop module is one of critical components for syzkaller fuzzing.
Bugs which involves the loop module prevents syzkaller from finding/testing
other bugs. But changes are continuously applied without careful review.
Therefore, the changes and code are not getting correct. Stable work cannot
come afterwards...