Re: mpt3sas fails to allocate budget_map and detects no devices

[Ming Lei <ming.lei@redhat.com>]

On Wed, Jan 05, 2022 at 06:00:41PM +0000, Martin Wilck wrote:
> Hello Ming, Sreekanth,
> 
> I'm observing a problem where mpt3sas fails to allocate the budget_map
> for any SCSI device, because attempted allocation is larger than the
> maximum possible. The issue is caused by the logic used in 020b0f0a3192
> ("scsi: core: Replace sdev->device_busy with sbitmap") 
> to calculate the bitmap size. This is observed with 5.16-rc8.
> 
> The controller at hand has properties can_queue=29865 and
> cmd_per_lun=7. The way these parameters are used in scsi_alloc_sdev()->

That two parameter looks bad, can_queue is too big, however cmd_per_lun
is so small.

> sbitmap_init_node(), this results in an sbitmap with 29865 maps, where
> only a single bit is used per map. On x86_64, this results in an
> attempt to allocate 29865 * 192 =  5734080 bytes for the sbitmap, which
> is larger than  PAGE_SIZE * (1 << (MAX_ORDER - 1)), and fails.

Bart has posted one patch for fixing the issue:

https://lore.kernel.org/linux-scsi/20211203231950.193369-2-bvanassche@acm.org/

but it isn't merged yet.

Martin, can we merge the above patch for fixing this issue?


Thanks,
Ming