Date: Thu, 5 Nov 2015 10:50:33 +0200
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: yalin wang <yalin.wang2010@gmail.com>, akpm@linux-foundation.org,
        kirill.shutemov@linux.intel.com, jmarchan@redhat.com,
        mgorman@techsingularity.net, ebru.akagunduz@gmail.com,
        willy@linux.intel.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] mm: fix kernel crash in khugepaged thread
Message-ID: <20151105085033.GB7614@node.shutemov.name>
References: <1445855960-28677-1-git-send-email-yalin.wang2010@gmail.com>
 <20151029003551.GB12018@node.shutemov.name>
 <563B0F72.5030908@suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <563B0F72.5030908@suse.cz>
User-Agent: Mutt/1.5.23.1 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1112
Lines: 28

On Thu, Nov 05, 2015 at 09:12:34AM +0100, Vlastimil Babka wrote:
> On 10/29/2015 01:35 AM, Kirill A. Shutemov wrote:
> >> @@ -2605,9 +2603,9 @@ out_unmap:
> >>  		/* collapse_huge_page will return with the mmap_sem released */
> >>  		collapse_huge_page(mm, address, hpage, vma, node);
> >>  	}
> >> -out:
> >> -	trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced,
> >> -				     none_or_zero, result, unmapped);
> >> +	trace_mm_khugepaged_scan_pmd(mm, pte_present(pteval) ?
> >> +			pte_pfn(pteval) : -1, writable, referenced,
> >> +			none_or_zero, result, unmapped);
> > 
> > maybe passing down pte instead of pfn?
> 
> Maybe just pass the page, and have tracepoint's fast assign check for !NULL and
> do page_to_pfn itself? That way the complexity and overhead is only in the
> tracepoint and when enabled.

Agreed.

-- 
 Kirill A. Shutemov
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/