From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx117.postini.com [74.125.245.117]) by kanga.kvack.org (Postfix) with SMTP id AE43A6B00DB for ; Wed, 22 May 2013 11:23:51 -0400 (EDT) From: "Kirill A. Shutemov" In-Reply-To: References: <1368321816-17719-1-git-send-email-kirill.shutemov@linux.intel.com> <1368321816-17719-34-git-send-email-kirill.shutemov@linux.intel.com> Subject: Re: [PATCHv4 33/39] thp, mm: implement do_huge_linear_fault() Content-Transfer-Encoding: 7bit Message-Id: <20130522152615.A4E22E0090@blue.fi.intel.com> Date: Wed, 22 May 2013 18:26:15 +0300 (EEST) Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton 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" , Dave Hansen , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Hillf Danton wrote: > On Sun, May 12, 2013 at 9:23 AM, Kirill A. Shutemov > wrote: > > page = vmf.page; > > + > > + /* > > + * If we asked for huge page we expect to get it or VM_FAULT_FALLBACK. > > + * If we don't ask for huge page it must be splitted in ->fault(). > > + */ > > + BUG_ON(PageTransHuge(page) != thp); > > + > Based on the log message in 34/39( > If the area of page cache required to create huge is empty, we create a > new huge page and return it.), the above trap looks bogus. The statement in 34/39 is true for (flags & FAULT_FLAG_TRANSHUGE). For !(flags & FAULT_FLAG_TRANSHUGE) huge page must be split in ->fault. The BUG_ON() above is shortcut for two checks: if (thp) BUG_ON(!PageTransHuge(page)); if (!thp) BUG_ON(PageTransHuge(page)); -- 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