Re: (subset) [PATCH 0/5] hyper-v: Don't assume cpu_possible_mask is dense

Martin K. Petersen
2025-01-02T22:47:40Z

On Wed, 02 Oct 2024 20:53:28 -0700, mhkelley58@gmail.com wrote:

> Code specific to Hyper-V guests currently assumes the cpu_possible_mask
> is "dense" -- i.e., all bit positions 0 thru (nr_cpu_ids - 1) are set,
> with no "holes". Therefore, num_possible_cpus() is assumed to be equal
> to nr_cpu_ids.
>
> Per a separate discussion[1], this assumption is not valid in the
> general case. For example, the function setup_nr_cpu_ids() in
> kernel/smp.c is coded to assume cpu_possible_mask may be sparse,
> and other patches have been made in the past to correctly handle
> the sparseness. See bc75e99983df1efd ("rcu: Correctly handle sparse
> possible cpu") as noted by Mark Rutland.
>
> [...]

Applied to 6.14/scsi-queue, thanks!

[4/5] scsi: storvsc: Don't assume cpu_possible_mask is dense
https://git.kernel.org/mkp/scsi/c/6cb7063feb2e

--
Martin K. Petersen Oracle Linux Engineering