On 9/3/24 17:58, SeongJae Park wrote:
On Tue, 3 Sep 2024 20:48:53 -0400 "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx> wrote:
* SeongJae Park <sj@xxxxxxxxxx> [240903 20:45]:
damon_test_three_regions_in_vmas() initializes a maple tree with
MM_MT_FLAGS. The flags contains MT_FLAGS_LOCK_EXTERN, which means
mt_lock of the maple tree will not be used. And therefore the maple
tree initialization code skips initialization of the mt_lock. However,
__link_vmas(), which adds vmas for test to the maple tree, uses the
mt_lock. In other words, the uninitialized spinlock is used. The
problem becomes celar when spinlock debugging is turned on, since it
Just in case you need to resend: s/celar/clear/
reports spinlock bad magic bug. Fix the issue by not using the mt_lock
as promised.
You can't do this, lockdep will tell you this is wrong.
Hmm, but lockdep was silence on my setup?
We need a lock and to use the lock for writes.
This code is executed by a single-thread test code. Do we still need the lock?
I'd suggest using different flags so the spinlock is used.
The reporter mentioned simply dropping MT_FLAGS_LOCK_EXTERN from the flags
causes suspicious RCU usage message. May I ask if you have a suggestion of
better flags?
Correct. I don't see those messages with your patch. From my perspective, this is
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Thanks,
Guenter
