From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161028Ab3BNWf6 (ORCPT ); Thu, 14 Feb 2013 17:35:58 -0500 Received: from kanga.kvack.org ([205.233.56.17]:58208 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759164Ab3BNWf5 (ORCPT ); Thu, 14 Feb 2013 17:35:57 -0500 Date: Thu, 14 Feb 2013 17:35:56 -0500 From: Benjamin LaHaise To: Andrew Morton , Kent Overstreet Cc: linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, Linux Kernel Subject: [PATCH] aio: v2: fix kioctx not being freed after cancellation at exit time Message-ID: <20130214223556.GA10806@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This v2 patch replaces both "aio: fix kioctx not being freed after cancellation at exit time" and "aio: only suppress events from cancelled kiocbs if free_ioctx() is in progress". Kent's feedback is indeed correct. The recent changes overhauling fs/aio.c introduced a bug that results in the kioctx not being freed when outstanding kiocbs are cancelled at exit_aio() time. Specifically, a kiocb that is cancelled has its completion events discarded by batch_complete_aio(), which then fails to wake up the process stuck in free_ioctx(). Fix this by removing the event suppression in batch_complete_aio() and modify the wait_event() condition in free_ioctx() appropriately. This patch was tested with the cancel operation in the thread based code posted yesterday. Signed-off-by: Benjamin LaHaise --- fs/aio.c | 15 +++------------ 1 files changed, 3 insertions(+), 12 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index dc52b0c..6ea766c 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -335,7 +335,9 @@ static void free_ioctx(struct kioctx *ctx) kunmap_atomic(ring); while (atomic_read(&ctx->reqs_available) < ctx->nr) { - wait_event(ctx->wait, head != ctx->shadow_tail); + wait_event(ctx->wait, + (head != ctx->shadow_tail) || + (atomic_read(&ctx->reqs_available) >= ctr->nr)); avail = (head <= ctx->shadow_tail ? ctx->shadow_tail : ctx->nr) - head; @@ -747,17 +749,6 @@ void batch_complete_aio(struct batch_complete *batch) n = rb_parent(n); } - if (unlikely(xchg(&req->ki_cancel, - KIOCB_CANCELLED) == KIOCB_CANCELLED)) { - /* - * Can't use the percpu reqs_available here - could race - * with free_ioctx() - */ - atomic_inc(&req->ki_ctx->reqs_available); - aio_put_req(req); - continue; - } - if (unlikely(req->ki_eventfd != eventfd)) { if (eventfd) { /* Make event visible */ -- 1.7.4.1 -- "Thought is the essence of where you are now."