as_arq scheduler alloc with 2.6.0-test8-mm1

No, you're on the right track. Actually, in the block device
you will allocate the queue, and the queue will then allocate
the elevator. First see if the queue is being properly allocated
and freed. If it is not, then the problem is in the SCSI layer.

Quoted 3 lines · Amit Patel

Hi

After doing some printk debugging looks like for

each

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block device we allocate elevator structure. But during cleanup the elevator->elevator_data is never freed. In printk I put printk in

as-iosched.c:as_alloc

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where I see elevator_data is allocated from as_arq pool and it should have been freed as a part of

block

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device cleanup through elevator_release function. I never see it coming to elevatore_release function.

I will try to walk through code some more and see

if I

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can figure out who was supposed to call elevator_release as part of cleanup. Let me know if

I

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am going on wrong track here.

Thanks
Amit

Quoted 11 lines · --- Nick Piggin

No, you're on the right track. Actually, in the block device
you will allocate the queue, and the queue will then allocate
the elevator. First see if the queue is being properly allocated
and freed. If it is not, then the problem is in the SCSI layer.

Hi Nick,

During scsi_scan.c:scsi_probe_and_add_lun it allocates scsi device and request_queue to send the scsi_request. If during this scan it finds no device attached to target it will deallocate request__queue. But since there was no disk found it never called add_disk and so it never go through blk_register_queue function to register elevator queue. So during clean up it just calles blk_cleanup_queue which does _not_ clean up elevator_data.

This is just what I think is happening by looking at the code. I might be missing something. But in this case either blk_cleanup_queue should clean elevator also as part of cleanup instead of it getting cleaned up through blk_unregister_queue or scsi layer needs to make some changes during scan. I do not know what implication it might have if cleanup is done as part of blk_cleanup_queue on other kind of block devices. I will try to put this cleanup as part of blk_cleanup_queue to see if it works.