Messages in this thread |  | | | Date | Thu, 5 Feb 2009 21:09:04 +0000 (GMT) | | From | Hugh Dickins <> | | Subject | Re: pud_bad vs pud_bad |
| |
On Thu, 5 Feb 2009, wli@movementarian.org wrote: > On Thu, 5 Feb 2009, wli@movementarian.org wrote: > >> The RW bit needs to be allowed to become read-only for hugetlb COW. > >> Changing it over to the 32-bit method is a bugfix by that token. > > On Thu, Feb 05, 2009 at 08:14:42PM +0000, Hugh Dickins wrote: > > If there's a bugfix to be made there, of course I'm in favour: > > but how come we've never seen such a bug? hugetlb COW has been > > around for a year or two by now, hasn't it? > > We can tell from the code that a write-protected pte mapping of a > 1GB hugetlb page would be flagged as bad. It must not be called on > ptes mapping hugetlb pages if they're not getting flagged.
Ah, I see what you mean now. Yes, the hugetlb case goes its own way and doesn't normally hit those p??_bad() macro/inlines; but we got caught out in follow_page() a year ago, a bad looked huge or a huge looked bad, but I forget the details at this instant.
Hugh
|  |