From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id BD4D16B004D for ; Fri, 27 Jan 2012 22:33:10 -0500 (EST) Received: by dake40 with SMTP id e40so2410212dak.14 for ; Fri, 27 Jan 2012 19:33:09 -0800 (PST) Date: Fri, 27 Jan 2012 19:32:49 -0800 (PST) From: Hugh Dickins Subject: Re: kernel bug: mmap, XIP, page faults, multiple threads In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Louis Alex Eisner Cc: Andrew Morton , Nick Piggin , linux-mm@kvack.org, Carsten Otte On Thu, 26 Jan 2012, Louis Alex Eisner wrote: > > I hope I'm sending this to the right people, but I wasn't sure who to > send it to, since I'm not entirely sure exactly where the bug lives. > Without further ado: > > Summary: > When multiple threads simultaneously attempt to write to the same page of a > file which has been mmapped using XIP for the first time, an unhandled > EBUSY signal causes the kernel to panic. Thanks a lot for your report, and all the info you carefully gathered. I confess that I haven't looked at it at all! Because I was thinking maybe I should take a look, and when did we last hear from Carsten? And though I now see more recent postings from him in other fields, what came first to my eye was this nugget below. It was white-space-damaged and wouldn't apply (I bet that's why it got lost), so I've fixed that up and reformatted the description, and added you as a Reporter - but otherwise it's as Carsten posted. Hugh