[Cluster-devel] Why does dlm_lock function fails when downconvert a dlm lock?
ghe at suse.com
Fri Aug 13 06:49:04 UTC 2021
On 2021/8/13 1:45, David Teigland wrote:
> On Thu, Aug 12, 2021 at 01:44:53PM +0800, Gang He wrote:
>> In fact, I can reproduce this problem stably.
>> I want to know if this error happen is by our expectation? since there is
>> not any extreme pressure test.
>> Second, how should we handle these error cases? call dlm_lock function
>> again? maybe the function will fails again, that will lead to kernel
>> soft-lockup after multiple re-tries.
> What's probably happening is that ocfs2 calls dlm_unlock(CANCEL) to cancel
> an in-progress dlm_lock() request. Before the cancel completes (or the
> original request completes), ocfs2 calls dlm_lock() again on the same
> resource. This dlm_lock() returns -EBUSY because the previous request has
> not completed, either normally or by cancellation. This is expected.
These dlm_lock and dlm_unlock are invoked in the same node, or the
> A couple options to try: wait for the original request to complete
> (normally or by cancellation) before calling dlm_lock() again, or retry
> dlm_lock() on -EBUSY.
If I retry dlm_lock() repeatedly, I just wonder if this will lead to
kernel soft lockup or waste lots of CPU.
If dlm_lock() function returns -EAGAIN, how should we handle this case?
retry it repeatedly?
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