blkcg, writeback: dead memcgs shouldn't contribute to writeback ownership arbitration
authorTejun Heo <tj@kernel.org>
Thu, 13 Jun 2019 22:30:41 +0000 (15:30 -0700)
committerJens Axboe <axboe@kernel.dk>
Sat, 15 Jun 2019 16:39:42 +0000 (10:39 -0600)
commit6631142229005e1b1c311a09efe9fb3cfdac8559
tree26f8b21314b83d627d3d0354d1abf3638397832a
parent71c814077de60b2e7415dac6f5c4e98f59d521fd
blkcg, writeback: dead memcgs shouldn't contribute to writeback ownership arbitration

wbc_account_io() collects information on cgroup ownership of writeback
pages to determine which cgroup should own the inode.  Pages can stay
associated with dead memcgs but we want to avoid attributing IOs to
dead blkcgs as much as possible as the association is likely to be
stale.  However, currently, pages associated with dead memcgs
contribute to the accounting delaying and/or confusing the
arbitration.

Fix it by ignoring pages associated with dead memcgs.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
fs/fs-writeback.c