On Tue, Nov 20, 2018 at 09:44:35AM +0800, Ming Lei wrote:
Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime from block layer's view, actually they don't because userspace may grab one kobject anytime via sysfs.
This patch fixes the issue by the following approach:
- introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing
all ctxs
- free all allocated ctxs and the 'blk_mq_ctxs' instance in release
handler of .mq_kobj
- grab one ref of .mq_kobj before initializing each ctx->kobj, so that
.mq_kobj is always released after all ctxs are freed.
This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE is enabled.
Reported-by: Guenter Roeck linux@roeck-us.net Cc: "jianchao.wang" jianchao.w.wang@oracle.com Cc: Guenter Roeck linux@roeck-us.net Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Signed-off-by: Ming Lei ming.lei@redhat.com
V3:
- keep to allocate q->queue_ctx via percpu allocator, so one extra pointer reference can be saved for getting ctx
V2:
- allocate 'blk_mq_ctx' inside blk_mq_init_allocated_queue()
- allocate q->mq_kobj directly
Not tested, but seems sane from a kobject point-of-view:
Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org