On Fri, Sep 6, 2019 at 11:17 AM James Morse <james.morse@xxxxxxx> wrote: > > Hi Pavel, > > On 21/08/2019 19:31, Pavel Tatashin wrote: > > There is a bug in create_safe_exec_page(), when page table is allocated > > it is not checked that table is allocated successfully: > > > > But it is dereferenced in: pgd_none(READ_ONCE(*pgdp)). > > If there is a bug, it shouldn't be fixed part way through a series. This makes it > difficult to backport the fix. > > Please split this out as an independent patch with a 'Fixes:' tag for the commit that > introduced the bug. > > > > Another issue, > > So this patch does two things? That is rarely a good idea. Again, this makes it difficult > to backport the fix. > > > > is that phys_to_ttbr() uses an offset in page table instead > > of pgd directly. > > If you were going to reuse this, that would be a bug. But because the only page that is > being mapped, is mapped to PAGE_SIZE, all the top bits will be 0. The offset calls are > boiler-plate. It doesn't look intentional, but its harmless. Yes, it is harmless otherwise the code would not work. But it is confusing to read, and looks broken. I will separate this change as two patches as you suggested. Thank you, Pasha
