Re: [PATCHv2 2/6] x86, mpx: do not set ->vm_ops on mpx VMAs

["Kirill A. Shutemov" <kirill@shutemov.name>]

On Thu, Jul 23, 2015 at 01:59:11PM -0700, Andrew Morton wrote:
> On Fri, 17 Jul 2015 14:53:09 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:
> 
> > MPX setups private anonymous mapping, but uses vma->vm_ops too.
> > This can confuse core VM, as it relies on vm->vm_ops to distinguish
> > file VMAs from anonymous.
> > 
> > As result we will get SIGBUS, because handle_pte_fault() thinks it's
> > file VMA without vm_ops->fault and it doesn't know how to handle the
> > situation properly.
> > 
> > Let's fix that by not setting ->vm_ops.
> > 
> > We don't really need ->vm_ops here: MPX VMA can be detected with VM_MPX
> > flag. And vma_merge() will not merge MPX VMA with non-MPX VMA, because
> > ->vm_flags won't match.
> > 
> > The only thing left is name of VMA. I'm not sure if it's part of ABI, or
> > we can just drop it. The patch keep it by providing arch_vma_name() on x86.
> > 
> > Build tested only.
> 
> mpx.c has changed.
> 
> arch/x86/mm/mpx.c: In function 'try_unmap_single_bt':
> arch/x86/mm/mpx.c:930: error: implicit declaration of function 'is_mpx_vma'
> 
> I'll drop this patch and see what happens.

Ingo has applied an updated version to x86/urgent:

https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?h=x86/urgent&id=a89652769470d12cd484ee3d3f7bde0742be8d96

-- 
 Kirill A. Shutemov

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>