Lukas Wunner wrote: > On Mon, Feb 12, 2024 at 11:30:54AM -0500, Mathieu Desnoyers wrote: > > Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for > > CONFIG_DAX=n to be consistent with the fact that CONFIG_DAX=y > > never returns NULL. > > All the callers of alloc_dax() only check for IS_ERR(). > > Doesn't this result in a change of behavior in all the callers? > Previously they'd ignore the NULL return value and continue, > now they'll error out. > > Given that, seems dangerous to add a Fixes tag with a v4.0 commit > and thus risk regressing all stable kernels. Oh, good catch, yes that Fixes tag should be: 4e4ced93794a dax: Move mandatory ->zero_page_range() check in alloc_dax() ...as that was the one that updated the alloc_dax() calling convention without fixing up the CONFIG_DAX=n case. This is a pre-requisite for restoring DAX operation on ARM32.
