[PATCH 0/3] ublk: fix maple tree lockdep warning and cleanup

[Ming Lei <tom.leiming@gmail.com>]

Hello Jens,

Fix the lockdep warning reported by Jens when running ublk selftests
with CONFIG_PROVE_RCU=y:

  lib/maple_tree.c:759 suspicious rcu_dereference_check() usage!

ublk_buf_cleanup() was iterating the maple tree without holding
mas_lock, triggering the splat from mas_find()'s internal
rcu_dereference_check().

Patch 1 fixes the warning by adding mas_lock around the iteration.
Patch 2 refactors the duplicated walk+erase+unpin loop into a shared
ublk_shmem_remove_ranges() helper. Patch 3 avoids holding the maple
tree spinlock across page unpinning by batching erased ranges into a
temporary xarray.


Thanks,

Ming Lei (3):
  ublk: fix maple tree lockdep warning in ublk_buf_cleanup
  ublk: refactor common helper ublk_shmem_remove_ranges()
  ublk: avoid unpinning pages under maple tree spinlock

 drivers/block/ublk_drv.c | 111 ++++++++++++++++++++++++---------------
 1 file changed, 70 insertions(+), 41 deletions(-)

-- 
2.53.0