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author | Brian Behlendorf <[email protected]> | 2015-09-23 15:59:04 -0700 |
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committer | Brian Behlendorf <[email protected]> | 2015-09-25 12:45:47 -0700 |
commit | ef5b2e1048eeeb7a81d932d38e52d897b33fca54 (patch) | |
tree | 054c798af341be4b1c2028f46571d196877847a7 /module/zfs/zio_checksum.c | |
parent | 04870568e6dae66d79ca144b0dcfa001324c562d (diff) |
Avoid blocking in arc_reclaim_thread()
As described in the comment above arc_reclaim_thread() it's critical
that the reclaim thread be careful about blocking. Just like it must
never wait on a hash lock, it must never wait on a task which can in
turn wait on the CV in arc_get_data_buf(). This will deadlock, see
issue #3822 for full backtraces showing the problem.
To resolve this issue arc_kmem_reap_now() has been updated to use the
asynchronous arc prune function. This means that arc_prune_async()
may now be called while there are still outstanding arc_prune_tasks.
However, this isn't a problem because arc_prune_async() already
keeps a reference count preventing multiple outstanding tasks per
registered consumer. Functionally, this behavior is the same as
the counterpart illumos function dnlc_reduce_cache().
Signed-off-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tim Chase <[email protected]>
Issue #3808
Issue #3834
Issue #3822
Diffstat (limited to 'module/zfs/zio_checksum.c')
0 files changed, 0 insertions, 0 deletions