From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750948AbeBPX5z (ORCPT ); Fri, 16 Feb 2018 18:57:55 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38282 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750824AbeBPX5x (ORCPT ); Fri, 16 Feb 2018 18:57:53 -0500 Date: Fri, 16 Feb 2018 15:57:52 -0800 From: Andrew Morton To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Naoya Horiguchi , Michal Hocko , Linus Torvalds , "Kirill A. Shutemov" , Nicholas Piggin Subject: Re: [PATCH] proc/kpageflags: add KPF_WAITERS Message-Id: <20180216155752.4a17cfd41875911c79807585@linux-foundation.org> In-Reply-To: <151834540184.176427.12174649162560874101.stgit@buzz> References: <151834540184.176427.12174649162560874101.stgit@buzz> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 11 Feb 2018 13:36:41 +0300 Konstantin Khlebnikov wrote: > KPF_WAITERS indicates tasks are waiting for a page lock or writeback. > This might be false-positive, in this case next unlock will clear it. Well, kpageflags is full of potential false-positives. Or do you think this flag is especially vulnerable? In other words, under what circumstances will we have KPF_WAITERS set when PG_locked and PG-writeback are clear? > This looks like worth information not only for kernel hacking. Why? What are the use-cases, in detail? How are we to justify this modification? > In tool page-types in non-raw mode treat KPF_WAITERS without > KPF_LOCKED and KPF_WRITEBACK as false-positive and hide it. > fs/proc/page.c | 1 + > include/uapi/linux/kernel-page-flags.h | 1 + > tools/vm/page-types.c | 7 +++++++ Please update Documentation/vm/pagemap.txt.