From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Weimer Subject: Re: [PATCH for 5.5 1/2] rseq: Fix: Clarify rseq.h UAPI rseq_cs memory reclaim requirements Date: Fri, 20 Dec 2019 21:37:59 +0100 Message-ID: <87imman36g.fsf@mid.deneb.enyo.de> References: <20191220201207.17389-1-mathieu.desnoyers@efficios.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20191220201207.17389-1-mathieu.desnoyers@efficios.com> (Mathieu Desnoyers's message of "Fri, 20 Dec 2019 15:12:06 -0500") Sender: linux-kernel-owner@vger.kernel.org To: Mathieu Desnoyers Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , "H . Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, stable@vger.kernel.org, Dmitry Vyukov , Neel Natu List-Id: linux-api@vger.kernel.org * Mathieu Desnoyers: > diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h > index 9a402fdb60e9..6f26b0b148a6 100644 > --- a/include/uapi/linux/rseq.h > +++ b/include/uapi/linux/rseq.h > @@ -100,7 +100,9 @@ struct rseq { > * instruction sequence block, as well as when the kernel detects that > * it is preempting or delivering a signal outside of the range > * targeted by the rseq_cs. Also needs to be set to NULL by user-space > - * before reclaiming memory that contains the targeted struct rseq_cs. > + * before reclaiming memory that contains the targeted struct rseq_cs > + * or reclaiming memory that contains the code refered to by the > + * start_ip and post_commit_offset fields of struct rseq_cs. Maybe mention that it's good practice to clear rseq_cs before returning from a function that contains a restartable sequence? That will deal with the dlclose issue because even if the function calls dlclose itself, unmapping something on call stack for dlclose is already undefined.