Re: [PATCH] mm: Loosen MADV_NOHUGEPAGE to enable Qemu postcopy on s390

From: Andrea Arcangeli <aarcange@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Jason J. Herne" <jjherne@linux.vnet.ibm.com>,
	linux-s390@vger.kernel.org, linux-mm@kvack.org,
	KVM list <kvm@vger.kernel.org>
Subject: Re: [PATCH] mm: Loosen MADV_NOHUGEPAGE to enable Qemu postcopy on s390
Date: Wed, 11 Nov 2015 21:42:34 +0100	[thread overview]
Message-ID: <20151111204234.GI4573@redhat.com> (raw)
In-Reply-To: <56439B56.1090105@de.ibm.com>

On Wed, Nov 11, 2015 at 08:47:34PM +0100, Christian Borntraeger wrote:
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Who is going to take this patch? If I should take the patch, I need an
> ACK from the memory mgmt folks.

I would suggest to resend in CC to Andrew to merge in -mm after taking
care of the below, as it's a mm common code part.

> 
> Christian
> 
> 
> >> ---
> >>  mm/huge_memory.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> >> index c29ddeb..a8b5347 100644
> >> --- a/mm/huge_memory.c
> >> +++ b/mm/huge_memory.c
> >> @@ -2025,7 +2025,7 @@ int hugepage_madvise(struct vm_area_struct *vma,
> >>  		/*
> >>  		 * Be somewhat over-protective like KSM for now!
> >>  		 */
> >> -		if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP))
> >> +		if (*vm_flags & VM_NO_THP)
> >>  			return -EINVAL;
> >>  		*vm_flags &= ~VM_HUGEPAGE;
> >>  		*vm_flags |= VM_NOHUGEPAGE;

If we make this change the MADV_HUGEPAGE must be taken care of too or
it doesn't make sense to threat them differently.

After taking care of the MADV_HUGEPAGE you can add my reviewed-by when
you resubmit to Andrew.

Thanks,
Andrea