From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757479AbbFPXFn (ORCPT ); Tue, 16 Jun 2015 19:05:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752469AbbFPXFe (ORCPT ); Tue, 16 Jun 2015 19:05:34 -0400 Date: Wed, 17 Jun 2015 01:04:26 +0200 From: Oleg Nesterov To: Al Viro , Andrew Morton , Benjamin LaHaise , Jeff Moyer Cc: linux-aio@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/3] aio_ring_remap: turn the ctx->dead check into WARN_ON() Message-ID: <20150616230426.GA15790@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150616230414.GA15776@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org atomic_read(&ctx->dead) in aio_ring_remap() looks confusing. kill_ioctx() sets ctx->dead and removes ctx from ->ioctx_table "atomically" under mm->ioctx_lock, so aio_ring_remap() can never see a dead ctx. If we really want this check, we should put it under WARN_ON() and it should not depend on aio_ring_file == file. Signed-off-by: Oleg Nesterov --- fs/aio.c | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 480440f..0693333 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -325,14 +325,14 @@ static int aio_ring_remap(struct file *file, struct vm_area_struct *vma) rcu_read_lock(); table = rcu_dereference(mm->ioctx_table); for (i = 0; i < table->nr; i++) { - struct kioctx *ctx; - - ctx = table->table[i]; - if (ctx && ctx->aio_ring_file == file) { - if (!atomic_read(&ctx->dead)) { - ctx->user_id = ctx->mmap_base = vma->vm_start; - res = 0; - } + struct kioctx *ctx = table->table[i]; + + if (!ctx || WARN_ON(atomic_read(&ctx->dead))) + continue; + + if (ctx->aio_ring_file == file) { + ctx->user_id = ctx->mmap_base = vma->vm_start; + res = 0; break; } } -- 1.5.5.1