From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f47.google.com (mail-qg0-f47.google.com [209.85.192.47]) by kanga.kvack.org (Postfix) with ESMTP id F24076B0038 for ; Tue, 11 Aug 2015 17:14:06 -0400 (EDT) Received: by qgdd90 with SMTP id d90so48274005qgd.3 for ; Tue, 11 Aug 2015 14:14:06 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id w74si5774059qha.69.2015.08.11.14.14.05 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Aug 2015 14:14:06 -0700 (PDT) Date: Tue, 11 Aug 2015 14:14:04 -0700 From: Andrew Morton Subject: Re: [PATCH] mm/hwpoison: fix panic due to split huge zero page Message-Id: <20150811141404.ecb19c1a66c32abf60d6663c@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Wanpeng Li Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Naoya Horiguchi On Tue, 11 Aug 2015 18:47:57 +0800 Wanpeng Li wrote: > > ... > > Huge zero page is allocated if page fault w/o FAULT_FLAG_WRITE flag. > The get_user_pages_fast() which called in madvise_hwpoison() will get > huge zero page if the page is not allocated before. Huge zero page is > a tranparent huge page, however, it is not an anonymous page. memory_failure > will split the huge zero page and trigger BUG_ON(is_huge_zero_page(page)); > After commit (98ed2b0: mm/memory-failure: give up error handling for > non-tail-refcounted thp), memory_failure will not catch non anon thp > from madvise_hwpoison path and this bug occur. So I'm assuming this patch is needed for 4.2 but not in earlier kernels. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org