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| author | Tejun Heo <tj@kernel.org> | 2015-07-02 02:53:37 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-07-02 16:46:00 +0200 |
| commit | a20135ffbc44545596f9b99c970de097fb497bdd (patch) | |
| tree | 18d7267ad1c0b0d603b4ca9cb1e43755c344f632 /lib/locking-selftest.c | |
| parent | writeback: don't embed root bdi_writeback_congested in bdi_writeback (diff) | |
| download | linux-a20135ffbc44545596f9b99c970de097fb497bdd.tar.xz linux-a20135ffbc44545596f9b99c970de097fb497bdd.zip | |
writeback: don't drain bdi_writeback_congested on bdi destruction
52ebea749aae ("writeback: make backing_dev_info host cgroup-specific
bdi_writebacks") made bdi (backing_dev_info) host per-cgroup wb's
(bdi_writeback's). As the congested state needs to be per-wb and
referenced from blkcg side and multiple wbs, the patch made all
non-root cong's (bdi_writeback_congested's) reference counted and
indexed on bdi.
When a bdi is destroyed, cgwb_bdi_destroy() tries to drain all
non-root cong's; however, this can hang indefinitely because wb's can
also be referenced from blkcg_gq's which are destroyed after bdi
destruction is complete.
This patch fixes the bug by updating bdi destruction to not wait for
cong's to drain. A cong is unlinked from bdi->cgwb_congested_tree on
bdi destuction regardless of its reference count as the bdi may go
away any point after destruction. wb_congested_put() checks whether
the cong is already unlinked on release.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jon Christopherson <jon@jons.org>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100681
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Tested-by: Jon Christopherson <jon@jons.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'lib/locking-selftest.c')
0 files changed, 0 insertions, 0 deletions