On Fri, 4 Mar 2022, Liam Howlett wrote: > * Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> [220304 13:49]: > > * Hugh Dickins <hughd@xxxxxxxxxx> [220303 23:36]: > > I just thought of something after my initial email > > How does the ->set_policy() requirement on tmpfs play out for the > mpol_equal() check earlier in that for loop? It took me a while to page all this back in (and remind myself of what is case 8) to answer that question! The answer is that the mpol_equal() check at the top of the loop is on an existing, unmodified vma; so it's right to assume that any necessary set_policy() has already been done. Whereas the mpol_equal() check being removed in this patch, is being done on a vma which may have just been extended to cover a greater range: so although the relevant set_policy() may have already been done on a part of its range, there is now another part which needs the policy applied. > > Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Thank you, your review is very welcome (but mainly I Cc'ed to alert you to how I'm probably stepping on your toes a little here - sorry). Hugh
