Re: [PATCH] nvme-multipath: set BLK_FEAT_ZONED only after the zone info is known

[Guixin Liu <kanie@linux.alibaba.com>]

在 2026/9/15 16:51, Guixin Liu 写道:
>
>
> 在 2026/9/15 14:36, Christoph Hellwig 写道:
>> On Mon, Sep 14, 2026 at 06:57:13PM +0800, Guixin Liu wrote:
>>> The namespace head is marked zoned at allocation time based only on
>>> the command set identifier, before any zone information has been
>>> queried.  If the zone info query fails on the first scan, the path
>>> namespace is registered without zoned limits while the head still
>>> advertises the zoned capability with a zone size of zero.  Reporting
>>> zones or writing to the head then shifts by ilog2(0), triggering the
>>> UBSAN shift-out-of-bounds report in the report-zones and write paths.
>>>
>>> Drop the zoned feature from the head allocation and inherit it from
>>> the path namespace: the head limits refresh already stacks the zoned
>>> feature, the zone size and the zone resource limits from the path
>>> queue, so the head matches the path namespace and becomes zoned once a
>>> revalidation succeeds.  This also stops marking the head zoned when
>>> CONFIG_BLK_DEV_ZONED is off, which used to fail the head allocation
>>> with a WARN.
>> Where do we actually stack it right now?
> The head stacks it in nvme_update_ns_info(): after the path namespace
> update it's own limits, queue_limits_stack_bdev() stacks the path
> queue into the head, and blk_stack_limits() inherits the BLK_FEAT_ZONED
> through BLK_FEAT_INHERIT_MASK, along with chunk_sectors and the zone
> resource limits. That happens before the head is registered, so
> blk_revalidate_disk_zones() see the zoned feature in place.
>
Hi Christoph, any feedback?

Best Regards,
Guixin Liu
> Best Regards,
> Guixin Liu