linux-kernel - Re: mm: VM_BUG_ON_PAGE(PageTail(page)) in mbind

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Message-ID: <20160126210534.GA22852@node.shutemov.name>
Date:	Tue, 26 Jan 2016 23:05:34 +0200
From:	"Kirill A. Shutemov" <kirill@...temov.name>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	Doug Gilbert <dgilbert@...erlog.com>,
	David Rientjes <rientjes@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Shiraz Hashim <shashim@...eaurora.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	linux-scsi@...r.kernel.org
Subject: Re: mm: VM_BUG_ON_PAGE(PageTail(page)) in mbind

On Tue, Jan 26, 2016 at 12:49:16PM -0800, Andrew Morton wrote:
> On Tue, 26 Jan 2016 22:28:29 +0200 "Kirill A. Shutemov" <kirill@...temov.name> wrote:
> 
> > Let's mark the VMA as VM_IO to indicate to mm core that the VMA is
> > migratable.
> > 
> > ...
> >
> > --- a/drivers/scsi/sg.c
> > +++ b/drivers/scsi/sg.c
> > @@ -1261,7 +1261,7 @@ sg_mmap(struct file *filp, struct vm_area_struct *vma)
> >  	}
> >  
> >  	sfp->mmap_called = 1;
> > -	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> > +	vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
> >  	vma->vm_private_data = sfp;
> >  	vma->vm_ops = &sg_mmap_vm_ops;
> >  	return 0;
> 
> I'll put cc:stable on this - I don't think we recently did anything to make
> this happen?

The VM_BUG_ON is new bb5b8589767a ("mm: make sure isolate_lru_page() is
never called for tail page"), but I don't think it changes the picture
much.

-- 
 Kirill A. Shutemov