Re: [PATCH] mm/damon/tests/vaddr-kunit: don't use mas_lock for MM_MT_FLAGS-initialized maple tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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





[Index of Archives]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Share Photos]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Device Mapper]

  Powered by Linux