On 07/10, Andrew Morton wrote: > > On Fri, 10 Jul 2015 18:51:21 +0200 Oleg Nesterov <o...@redhat.com> wrote: > > > special_mapping_fault() is absolutely broken. It seems it was always > > wrong, but this didn't matter until vdso/vvar started to use more than > > one page. > > > > The patches are the same, just 1/3 was re-diffed on top of the recent > > 6b7339f4c31ad "mm: avoid setting up anonymous pages into file mapping" > > from Kirill. > > > > And after this change vma_is_anonymous() becomes really trivial, it > > simply checks vm_ops == NULL. However, I do think the helper makes > > sense. There are a lot of ->vm_ops != NULL checks, the helper makes > > the caller's code more understandable (self-documented) and this is > > more grep-friendly. > > I'm trying to work out which kernel version(s) this should go into, > without a lot of success. > > What do we think the worst-case effects of the bug?
Ah, I should have mentioned this. And when I re-read my messages I see that "absolutely broken" looks like "should be fixed asap". Sorry for confusion. No, this bug is not serious. Nothing bad can happen from the kernel perspective. And I doubt that some application will ever unmap/remap the part of vdso or any other install_special_mapping() user. So this is just correctness fix. In fact, to me the main problem is that I was totally confused when I tried to read/understand this code ;) Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/