[PATCH 0/2] blk-mq: fix oops caused by CPU hotplug

From: Ming Lei
Date: Sun Apr 19 2015 - 11:33:00 EST


Hi Guys,

Dongsu Park reported[1] that kernel oops can be triggered easily by
CPU plug when there is pending I/O on virtio-scsi.

Turns out two problems exist and both can trigger oops by CPU plug:
- timeout handling vs CPU hotplug, especially unmapped hw queue tags
is still touched by timeout handler
- in case of shared tags, there is one bug about setting and checking
hctx->tags during CPU hotplug

The two patches fix the two problem, and in my virtio-scsi test
oops does disapper with the change.

[1], http://marc.info/?t=142926389200008&r=1&w=2

Thanks,
Ming Lei


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