From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id 0D1CA6B0044 for ; Tue, 8 May 2012 19:10:15 -0400 (EDT) Received: by obbwd18 with SMTP id wd18so14324946obb.14 for ; Tue, 08 May 2012 16:10:15 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <20120502081705.GB16976@quack.suse.cz> <20120502091837.GC16976@quack.suse.cz> <20120502192325.GA18339@quack.suse.cz> Date: Wed, 9 May 2012 09:10:15 +1000 Message-ID: Subject: Re: [PATCH] Describe race of direct read and fork for unaligned buffers From: Nick Piggin Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: mtk.manpages@gmail.com, Jan Kara , Jeff Moyer , LKML , linux-man@vger.kernel.org, linux-mm@kvack.org, mgorman@suse.de, Andrea Arcangeli , Woodman On 6 May 2012 01:29, KOSAKI Motohiro wrote: >> So, am I correct to assume that right text to add to the page is as belo= w? >> >> Nick, can you clarify what you mean by "quiesced"? > > finished? Yes exactly. That might be a simpler word. Thanks! > >> >> [[ >> O_DIRECT IOs should never be run concurrently with fork(2) system call, >> when the memory buffer is anonymous memory, or comes from mmap(2) >> with MAP_PRIVATE. >> >> Any such IOs, whether submitted with asynchronous IO interface or from >> another thread in the process, should be quiesced before fork(2) is call= ed. >> Failure to do so can result in data corruption and undefined behavior in >> parent and child processes. >> >> This restriction does not apply when the memory buffer for the O_DIRECT >> IOs comes from mmap(2) with MAP_SHARED or from shmat(2). >> Nor does this restriction apply when the memory buffer has been advised >> as MADV_DONTFORK with madvise(2), ensuring that it will not be available >> to the child after fork(2). >> ]] > > I don't have good English and I can't make editorial check. But at least, > I don't find any technical incorrect explanation here. > > =C2=A0Acked-by: KOSAKI Motohiro -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org