Re: [PATCH V2 3/7] dax/fsdev: fix kaddr for multi-range and fail probe on invalid pgmap offset

[John Groves <John@groves.net>]

On 26/05/26 04:31PM, Dave Jiang wrote:
> 
> 
> On 5/22/26 12:19 PM, John Groves wrote:
> > From: John Groves <John@Groves.net>
> > 
> > Two fixes for virtual address handling in fsdev:
> > 
> > 1. Use __va(phys) instead of virt_addr + linear_offset for the kaddr
> >    return in __fsdev_dax_direct_access(). The previous code added a
> >    device-linear byte offset to virt_addr (which is __va of ranges[0]),
> >    but for multi-range devices with physical gaps between ranges, this
> >    linear arithmetic crosses the gap and produces a wrong kernel virtual
> >    address. Using __va(phys) where phys comes from dax_pgoff_to_phys()
> >    is correct for any range layout because the direct map translates
> >    each physical address independently.
> > 
> > 2. Convert the WARN_ON to a fatal error when pgmap_phys > phys. This
> >    condition means the remapped region starts after the device's data
> >    region, which is an impossible state. Previously the probe continued
> >    with data_offset=0, leaving virt_addr silently misaligned. Now probe
> >    returns -EINVAL with a diagnostic message.
> 
> Split to 2 different patches I'd say.
> 
> DJ

Agree - done. Thanks!

John

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