On Wed, Nov 15, 2023 at 08:29:01PM -0500, Peter Xu wrote: > This seems to be a bug not by any report but by code observations. > > When GUP sees a devpmd or devpud, it should return whatever value returned > from follow_devmap_p[mu]d(). If page==NULL returned, it means a fault is > probably required. Skipping return the NULL should allow the code to fall > through, which can cause unexpected behavior. > > It was there at least before the follow page rework (080dbb618b) in 2017, > so 6 years. Not yet digging for a Fixes, assuming it can hardly trigger > even if the logical bug does exist. > > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> I'd still add a fixes tag and send if off to Linux for 6.7-rc instead of letting it linger. Otherwise looks good: Reviewed-by: Christoph Hellwig <hch@xxxxxx>
