linux-kernel - Re: [PATCH v3] mm: softdirty: enable write notifications on VMAs after VM

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Message-ID: <20140824192251.GL25918@moon>
Date:	Sun, 24 Aug 2014 23:22:51 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	"Kirill A. Shutemov" <kirill@...temov.name>
Cc:	Peter Feiner <pfeiner@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Pavel Emelyanov <xemul@...allels.com>,
	Jamie Liu <jamieliu@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3] mm: softdirty: enable write notifications on VMAs
 after VM_SOFTDIRTY cleared

On Sun, Aug 24, 2014 at 10:59:24AM +0300, Kirill A. Shutemov wrote:
...
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index c1f2ea4..1b61fbc 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -1470,6 +1470,10 @@ int vma_wants_writenotify(struct vm_area_struct *vma)
> >  	if (vma->vm_ops && vma->vm_ops->page_mkwrite)
> >  		return 1;
> >  
> > +	/* Do we need to track softdirty? */
> > +	if (!(vm_flags & VM_SOFTDIRTY))
> 
> This will give false-positive if CONFIG_MEM_SOFT_DIRTY is disabled, since
> VM_SOFTDIRTY is 0 in this case:
> 
> 	if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
> 
> Otherwise looks good to me.
> 
> Suggested-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Really sorry for delay. Thanks a huge, guys!

Reviewed-by: Cyrill Gorcunov <gorcunov@...nvz.org>
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