From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id E0F706B0069 for ; Mon, 2 Oct 2017 18:45:29 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id j73so1646314lfg.4 for ; Mon, 02 Oct 2017 15:45:29 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id s197sor2648683wmd.16.2017.10.02.15.45.28 for (Google Transport Security); Mon, 02 Oct 2017 15:45:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20170927233224.31676-1-nicolas.pitre@linaro.org> <20170927233224.31676-5-nicolas.pitre@linaro.org> <20171001083052.GB17116@infradead.org> From: Richard Weinberger Date: Tue, 3 Oct 2017 00:45:27 +0200 Message-ID: Subject: Re: [PATCH v4 4/5] cramfs: add mmap support Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Nicolas Pitre Cc: Christoph Hellwig , Alexander Viro , "linux-mm@kvack.org" , linux-fsdevel , "linux-embedded@vger.kernel.org" , LKML , Chris Brandt On Mon, Oct 2, 2017 at 12:29 AM, Nicolas Pitre wrote: > On Sun, 1 Oct 2017, Christoph Hellwig wrote: > >> up_read(&mm->mmap_sem) in the fault path is a still a complete >> no-go, >> >> NAK > > Care to elaborate? > > What about mm/filemap.c:__lock_page_or_retry() then? As soon you up_read() in the page fault path other tasks will race with you before you're able to grab the write lock. HTH -- Thanks, //richard -- 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