From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx124.postini.com [74.125.245.124]) by kanga.kvack.org (Postfix) with SMTP id 870F06B0027 for ; Thu, 28 Mar 2013 11:30:05 -0400 (EDT) From: "Kirill A. Shutemov" In-Reply-To: <514CA325.3010104@sr71.net> References: <1363283435-7666-1-git-send-email-kirill.shutemov@linux.intel.com> <1363283435-7666-19-git-send-email-kirill.shutemov@linux.intel.com> <514CA325.3010104@sr71.net> Subject: Re: [PATCHv2, RFC 18/30] thp, mm: truncate support for transparent huge page cache Content-Transfer-Encoding: 7bit Message-Id: <20130328153152.54DDAE0085@blue.fi.intel.com> Date: Thu, 28 Mar 2013 17:31:52 +0200 (EET) Sender: owner-linux-mm@kvack.org List-ID: To: Dave Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andrew Morton , Al Viro , Hugh Dickins , Wu Fengguang , Jan Kara , Mel Gorman , linux-mm@kvack.org, Andi Kleen , Matthew Wilcox , "Kirill A. Shutemov" , Hillf Danton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Dave wrote: > On 03/14/2013 10:50 AM, Kirill A. Shutemov wrote: > > @@ -280,6 +291,7 @@ void truncate_inode_pages_range(struct address_space *mapping, > > if (index > end) > > break; > > > > + VM_BUG_ON(PageTransHuge(page)); > > lock_page(page); > > WARN_ON(page->index != index); > > wait_on_page_writeback(page); > > This looks to be during the second truncate pass where things are > allowed to block. What's the logic behind it not being possible to > encounter TransHugePage()s here? Good question. The only way how the page can be created from under us is collapsing, but it's not implemented for file pages and I'm not sure yet how to implement it... Probably, I'll replace the BUG with if (PageTransHuge(page)) split_huge_page(page); It should be good enough. -- Kirill A. Shutemov -- 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