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: > > 1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing > all ctxs > > 2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release > handler of .mq_kobj > > 3) 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@xxxxxxxxxxxx> > Cc: "jianchao.wang" <jianchao.w.wang@xxxxxxxxxx> > Cc: Guenter Roeck <linux@xxxxxxxxxxxx> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > 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@xxxxxxxxxxxxxxxxxxx>
