linux-kernel - Re: could you clarify mm/mempolicy: fix !vma in new_vma

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Message-ID: <20140106141827.GB27602@dhcp22.suse.cz>
Date:	Mon, 6 Jan 2014 15:18:27 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Bob Liu <lliubbo@...il.com>
Cc:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Bob Liu <bob.liu@...cle.com>, Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: could you clarify mm/mempolicy: fix !vma in new_vma_page()

On Mon 06-01-14 20:45:54, Bob Liu wrote:
[...]
>  544         if (PageAnon(page)) {
>  545                 struct anon_vma *page__anon_vma = page_anon_vma(page);
>  546                 /*
>  547                  * Note: swapoff's unuse_vma() is more efficient with this
>  548                  * check, and needs it to match anon_vma when KSM is active.
>  549                  */
>  550                 if (!vma->anon_vma || !page__anon_vma ||
>  551                     vma->anon_vma->root != page__anon_vma->root)
>  552                         return -EFAULT;
>  553         } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
>  554                 if (!vma->vm_file ||
>  555                     vma->vm_file->f_mapping != page->mapping)
>  556                         return -EFAULT;
>  557         } else
>  558                 return -EFAULT;
> 
> That's the "other conditions" and the reason why we can't use
> BUG_ON(!vma) in new_vma_page().

Sorry, I wasn't clear with my question. I was interested in which of
these triggered and why only for hugetlb pages?

-- 
Michal Hocko
SUSE Labs
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