[Bug 1805693] Re: User reports a hang on 18.04 LTS(4.15.18) under a heavy I/O load

** Changed in: linux (Ubuntu)
Importance: Undecided => High

** Changed in: linux (Ubuntu)
Status: Incomplete => Triaged

** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New

** Changed in: linux (Ubuntu Bionic)
Status: New => Triaged

** Changed in: linux (Ubuntu Bionic)
Importance: Undecided => High

** Tags added: kernel-da-key

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https://bugs.launchpad.net/bugs/1805693

Title:
User reports a hang on 18.04 LTS(4.15.18) under a heavy I/O load

Status in linux package in Ubuntu:
Triaged
Status in linux source package in Bionic:
Triaged

Bug description:
User reports a hang under heavy I/O:

The IO hang problem on our cloud is caused by IO hang in block-wbt wbt_wait.
The fix commit id is 2887e41b910bb14fd847cf01ab7a5993db989d88. It is a block write buffer throttle queue lock contention and thundering herd issue in wbt_wait()

We can recreate the problem easily by running concurrent IO from
multiple VMs with sequential write. We can provide fio workload as
needed for recreate.

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