Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752647AbbGRQ2v (ORCPT ); Sat, 18 Jul 2015 12:28:51 -0400 Received: from mail-pa0-f53.google.com ([209.85.220.53]:35233 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752518AbbGRQ2t (ORCPT ); Sat, 18 Jul 2015 12:28:49 -0400 From: Akinobu Mita To: linux-kernel@vger.kernel.org Cc: Akinobu Mita , Keith Busch , Jens Axboe , Ming Lei Subject: [PATCH v3 1/7] blk-mq: avoid access hctx->tags->cpumask before allocation Date: Sun, 19 Jul 2015 01:28:17 +0900 Message-Id: <1437236903-31617-2-git-send-email-akinobu.mita@gmail.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437236903-31617-1-git-send-email-akinobu.mita@gmail.com> References: <1437236903-31617-1-git-send-email-akinobu.mita@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1631 Lines: 51 When unmapped hw queue is remapped after CPU topology is changed, hctx->tags->cpumask is set before hctx->tags is allocated in blk_mq_map_swqueue(). In order to fix this null pointer dereference, hctx->tags must be allocated before configuring hctx->tags->cpumask. Fixes: f26cdc8536 ("blk-mq: Shared tag enhancements") Signed-off-by: Akinobu Mita Cc: Keith Busch Cc: Jens Axboe Cc: Ming Lei --- block/blk-mq.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 7d842db..f29f766 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1821,7 +1821,6 @@ static void blk_mq_map_swqueue(struct request_queue *q) hctx = q->mq_ops->map_queue(q, i); cpumask_set_cpu(i, hctx->cpumask); - cpumask_set_cpu(i, hctx->tags->cpumask); ctx->index_hw = hctx->nr_ctx; hctx->ctxs[hctx->nr_ctx++] = ctx; } @@ -1861,6 +1860,14 @@ static void blk_mq_map_swqueue(struct request_queue *q) hctx->next_cpu = cpumask_first(hctx->cpumask); hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; } + + queue_for_each_ctx(q, ctx, i) { + if (!cpu_online(i)) + continue; + + hctx = q->mq_ops->map_queue(q, i); + cpumask_set_cpu(i, hctx->tags->cpumask); + } } static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/