From patchwork Thu Jan 9 06:21:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 11325087 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 992D06C1 for ; Thu, 9 Jan 2020 06:21:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76F3B2072E for ; Thu, 9 Jan 2020 06:21:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eYB6CtW9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727961AbgAIGVc (ORCPT ); Thu, 9 Jan 2020 01:21:32 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:21587 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727998AbgAIGVc (ORCPT ); Thu, 9 Jan 2020 01:21:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578550892; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tGjxHmFlju7WrnsYJiIRBK64P2R32jVIc38DBQZoWpA=; b=eYB6CtW96tEDI0Z6hceYGq7L4Qp2nHjghCncJkpYWeqWUHu355ePkG+E3LqoTKZidzJBGl BTRAjwcpS6AwDHnISv+HKSw6KuvLvk1vHYXq8iR4QL/Jw1oPgZUXYsl8BT3b9mzqVj4jx/ aG6nmAAvOqkufQSiJkcgDWg2S0aBejE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-391-5mF-0zymPxG-SB3Ndzofvg-1; Thu, 09 Jan 2020 01:21:28 -0500 X-MC-Unique: 5mF-0zymPxG-SB3Ndzofvg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 67BAF800EBF; Thu, 9 Jan 2020 06:21:27 +0000 (UTC) Received: from localhost (ovpn-8-30.pek2.redhat.com [10.72.8.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id 38CDB5DA60; Thu, 9 Jan 2020 06:21:23 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Yufen Yu , Christoph Hellwig , Hou Tao Subject: [PATCH 1/4] block: fix use-after-free on cached last_lookup partition Date: Thu, 9 Jan 2020 14:21:06 +0800 Message-Id: <20200109062109.2313-2-ming.lei@redhat.com> In-Reply-To: <20200109062109.2313-1-ming.lei@redhat.com> References: <20200109062109.2313-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org delete_partition() clears the cached last_lookup partition. However the .last_lookup cache may be overwritten by one IO path after it is cleared from delete_partition(). Then another IO path may use the cached deleting partition after __delete_partition() is called, then use-after-free is triggered on the cached partition. Fixes the issue by the following approach: 1) always get the partition's refcount via hd_struct_try_get() before setting .last_lookup 2) move clearing .last_lookup from delete_partition() to __delete_partition() which is release handle of the partition's percpu-refcount, so that no IO path can overwrite .last_lookup after it is cleared in __delete_partition(). It is one candidate approach of Yufen's patch[1] which adds overhead in fast path by indirect lookup which may introduce one extra cacheline in IO path. Also this patch relies on percpu-refcount's protection, and it is easier to understand and verify. [1] https://lore.kernel.org/linux-block/20200109013551.GB9655@ming.t460p/T/#t Reported-by: Yufen Yu Cc: Christoph Hellwig Cc: Hou Tao Signed-off-by: Ming Lei --- block/blk-core.c | 12 ------------ block/genhd.c | 6 +++++- block/partition-generic.c | 10 +++++++++- include/linux/genhd.h | 1 + 4 files changed, 15 insertions(+), 14 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 089e890ab208..79599f5fd5b7 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1365,18 +1365,6 @@ void blk_account_io_start(struct request *rq, bool new_io) part_stat_inc(part, merges[rw]); } else { part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq)); - if (!hd_struct_try_get(part)) { - /* - * The partition is already being removed, - * the request will be accounted on the disk only - * - * We take a reference on disk->part0 although that - * partition will never be deleted, so we can treat - * it as any other partition. - */ - part = &rq->rq_disk->part0; - hd_struct_get(part); - } part_inc_in_flight(rq->q, part, rw); rq->part = part; } diff --git a/block/genhd.c b/block/genhd.c index ff6268970ddc..6029c94510f0 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -286,17 +286,21 @@ struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector) ptbl = rcu_dereference(disk->part_tbl); part = rcu_dereference(ptbl->last_lookup); - if (part && sector_in_part(part, sector)) + if (part && sector_in_part(part, sector) && hd_struct_try_get(part)) return part; for (i = 1; i < ptbl->len; i++) { part = rcu_dereference(ptbl->part[i]); if (part && sector_in_part(part, sector)) { + if (!hd_struct_try_get(part)) + goto exit; rcu_assign_pointer(ptbl->last_lookup, part); return part; } } + exit: + hd_struct_get(&disk->part0); return &disk->part0; } EXPORT_SYMBOL_GPL(disk_map_sector_rcu); diff --git a/block/partition-generic.c b/block/partition-generic.c index 1d20c9cf213f..1739f750dbf2 100644 --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -262,6 +262,12 @@ static void delete_partition_work_fn(struct work_struct *work) void __delete_partition(struct percpu_ref *ref) { struct hd_struct *part = container_of(ref, struct hd_struct, ref); + struct disk_part_tbl *ptbl = + rcu_dereference_protected(part->disk->part_tbl, 1); + + rcu_assign_pointer(ptbl->last_lookup, NULL); + put_device(disk_to_dev(part->disk)); + INIT_RCU_WORK(&part->rcu_work, delete_partition_work_fn); queue_rcu_work(system_wq, &part->rcu_work); } @@ -283,8 +289,9 @@ void delete_partition(struct gendisk *disk, int partno) if (!part) return; + get_device(disk_to_dev(disk)); rcu_assign_pointer(ptbl->part[partno], NULL); - rcu_assign_pointer(ptbl->last_lookup, NULL); + kobject_put(part->holder_dir); device_del(part_to_dev(part)); @@ -349,6 +356,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno, p->nr_sects = len; p->partno = partno; p->policy = get_disk_ro(disk); + p->disk = disk; if (info) { struct partition_meta_info *pinfo = alloc_part_info(disk); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 8bb63027e4d6..1b09cfe00aa3 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -130,6 +130,7 @@ struct hd_struct { struct disk_stats dkstats; #endif struct percpu_ref ref; + struct gendisk *disk; struct rcu_work rcu_work; }; From patchwork Thu Jan 9 06:21:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 11325089 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 06CF5139A for ; Thu, 9 Jan 2020 06:21:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D9D0B2072E for ; Thu, 9 Jan 2020 06:21:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Gywq3+Bq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727916AbgAIGVi (ORCPT ); Thu, 9 Jan 2020 01:21:38 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:60360 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725893AbgAIGVi (ORCPT ); Thu, 9 Jan 2020 01:21:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578550897; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ew5IR1SLoji8W9+I8kKsPLUpLqL4mxiunsfZvG7bXYw=; b=Gywq3+BqISwtA88GGyLmXEDuIgeewxEGardfBHIJRopkmX4nEHaIqmjIo6TOzDGMn5rw8Z 1FIAQKOtw3InYrJy43OjF6+/2EtxBbHeQ5xfUaMP8RlEe8lPgn0klL4L79gZ4hEPzyokDB OCAwFkqzTc12EnVJXO7ONmFjONtJtfg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-190-HiamYrTgPZ2jFbvVMAl-AQ-1; Thu, 09 Jan 2020 01:21:33 -0500 X-MC-Unique: HiamYrTgPZ2jFbvVMAl-AQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8C482477; Thu, 9 Jan 2020 06:21:32 +0000 (UTC) Received: from localhost (ovpn-8-30.pek2.redhat.com [10.72.8.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id 858D6271AF; Thu, 9 Jan 2020 06:21:29 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Yufen Yu , Christoph Hellwig , Hou Tao Subject: [PATCH 2/4] block: only define 'nr_sects_seq' in hd_part for 32bit SMP Date: Thu, 9 Jan 2020 14:21:07 +0800 Message-Id: <20200109062109.2313-3-ming.lei@redhat.com> In-Reply-To: <20200109062109.2313-1-ming.lei@redhat.com> References: <20200109062109.2313-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The seqcount of 'nr_sects_seq' is only needed in case of 32bit SMP, so define it just for 32bit SMP. Cc: Yufen Yu Cc: Christoph Hellwig Cc: Hou Tao Signed-off-by: Ming Lei --- block/genhd.c | 2 +- block/partition-generic.c | 2 +- include/linux/genhd.h | 9 +++++++++ 3 files changed, 11 insertions(+), 2 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 6029c94510f0..bfc4148ec341 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1506,7 +1506,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) * TODO: Ideally set_capacity() and get_capacity() should be * converted to make use of bd_mutex and sequence counters. */ - seqcount_init(&disk->part0.nr_sects_seq); + hd_sects_seq_init(&disk->part0); if (hd_ref_init(&disk->part0)) { hd_free_part(&disk->part0); kfree(disk); diff --git a/block/partition-generic.c b/block/partition-generic.c index 1739f750dbf2..eb606c2c3d6c 100644 --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -345,7 +345,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno, goto out_free; } - seqcount_init(&p->nr_sects_seq); + hd_sects_seq_init(p); pdev = part_to_dev(p); p->start_sect = start; diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 1b09cfe00aa3..5f5718ce5e86 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -113,7 +113,9 @@ struct hd_struct { * can be non-atomic on 32bit machines with 64bit sector_t. */ sector_t nr_sects; +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) seqcount_t nr_sects_seq; +#endif sector_t alignment_offset; unsigned int discard_alignment; struct device __dev; @@ -713,6 +715,13 @@ static inline void hd_free_part(struct hd_struct *part) percpu_ref_exit(&part->ref); } +static inline void hd_sects_seq_init(struct hd_struct *p) +{ +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + seqcount_init(&p->nr_sects_seq); +#endif +} + /* * Any access of part->nr_sects which is not protected by partition * bd_mutex or gendisk bdev bd_mutex, should be done using this From patchwork Thu Jan 9 06:21:08 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 11325091 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 700566C1 for ; Thu, 9 Jan 2020 06:21:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44E212072E for ; Thu, 9 Jan 2020 06:21:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cNtV79Gi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727985AbgAIGVl (ORCPT ); Thu, 9 Jan 2020 01:21:41 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:54256 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725893AbgAIGVl (ORCPT ); Thu, 9 Jan 2020 01:21:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578550900; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RdOup2ZdUA6kr1X5B9TVP+fnISExoxWGQURfZsDFWLs=; b=cNtV79Gi+o/I5HeRjXxQqWa+gMRDfS79HktqePpy3CFKf7mB6M3fZWHcHP6zJ2UZOFjES7 cNB/FYd0LKcF6W/KcG1pqKq3mm45XJDweK6GssvcjWujqN5JU7MzB4sN8a/VfvB7NouewF PlLgIltyyCgY62b5ebxI5Nh6PYBhfxo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-92-Y2Sv-VUgOAujQXOEz6LUJA-1; Thu, 09 Jan 2020 01:21:39 -0500 X-MC-Unique: Y2Sv-VUgOAujQXOEz6LUJA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C3F31801E72; Thu, 9 Jan 2020 06:21:37 +0000 (UTC) Received: from localhost (ovpn-8-30.pek2.redhat.com [10.72.8.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id B32FE7FB7C; Thu, 9 Jan 2020 06:21:34 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Yufen Yu , Christoph Hellwig , Hou Tao Subject: [PATCH 3/4] block: re-organize fields of 'struct hd_part' Date: Thu, 9 Jan 2020 14:21:08 +0800 Message-Id: <20200109062109.2313-4-ming.lei@redhat.com> In-Reply-To: <20200109062109.2313-1-ming.lei@redhat.com> References: <20200109062109.2313-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Put all fields accessed in IO path together at the beginning of the struct, so that all can be fetched in single cacheline. Cc: Yufen Yu Cc: Christoph Hellwig Cc: Hou Tao Signed-off-by: Ming Lei --- include/linux/genhd.h | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 5f5718ce5e86..4c6a998a0c56 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -116,6 +116,14 @@ struct hd_struct { #if BITS_PER_LONG==32 && defined(CONFIG_SMP) seqcount_t nr_sects_seq; #endif + unsigned long stamp; +#ifdef CONFIG_SMP + struct disk_stats __percpu *dkstats; +#else + struct disk_stats dkstats; +#endif + struct percpu_ref ref; + sector_t alignment_offset; unsigned int discard_alignment; struct device __dev; @@ -125,13 +133,6 @@ struct hd_struct { #ifdef CONFIG_FAIL_MAKE_REQUEST int make_it_fail; #endif - unsigned long stamp; -#ifdef CONFIG_SMP - struct disk_stats __percpu *dkstats; -#else - struct disk_stats dkstats; -#endif - struct percpu_ref ref; struct gendisk *disk; struct rcu_work rcu_work; }; From patchwork Thu Jan 9 06:21:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 11325093 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7BB1F6C1 for ; Thu, 9 Jan 2020 06:21:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4FF2E2072E for ; Thu, 9 Jan 2020 06:21:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HU6p1ANG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727995AbgAIGVo (ORCPT ); Thu, 9 Jan 2020 01:21:44 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:48103 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725893AbgAIGVo (ORCPT ); Thu, 9 Jan 2020 01:21:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578550903; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1VDpRehaaX2VwZ6C6bv0cU3CdbWdM8MhHbEZNbnXnC8=; b=HU6p1ANGoOYtnrA76gl4Muc7bbkw0JJ0xmjYHfIitYJA6MwGG0Fj35rXY2KVVQQt0vPTDg cdgzcjGEQRTFA/Z0EHQoFK+TzGNMoEk7wmtkuvIwCde3ZANXgDI4BxgyXNr/ubh2JQyZzu 7UiY+8YU9g8ue99KVDAeQYYfykNvw2s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-204-FGycPvs2OJ-WAGZrbB7J0Q-1; Thu, 09 Jan 2020 01:21:42 -0500 X-MC-Unique: FGycPvs2OJ-WAGZrbB7J0Q-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 994A0107ACC7; Thu, 9 Jan 2020 06:21:40 +0000 (UTC) Received: from localhost (ovpn-8-30.pek2.redhat.com [10.72.8.30]) by smtp.corp.redhat.com (Postfix) with ESMTP id E2DC05DA32; Thu, 9 Jan 2020 06:21:39 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Yufen Yu , Christoph Hellwig , Hou Tao Subject: [PATCH 4/4] block: don't hold part0's refcount in IO path Date: Thu, 9 Jan 2020 14:21:09 +0800 Message-Id: <20200109062109.2313-5-ming.lei@redhat.com> In-Reply-To: <20200109062109.2313-1-ming.lei@redhat.com> References: <20200109062109.2313-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org gendisk can't be gone when there is IO activity, so not hold part0's refcount in IO path. Cc: Yufen Yu Cc: Christoph Hellwig Cc: Hou Tao Signed-off-by: Ming Lei --- block/blk-core.c | 3 ++- block/genhd.c | 1 - 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 79599f5fd5b7..a1184a59819a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1345,7 +1345,8 @@ void blk_account_io_done(struct request *req, u64 now) part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns)); part_dec_in_flight(req->q, part, rq_data_dir(req)); - hd_struct_put(part); + if (part->partno) + hd_struct_put(part); part_stat_unlock(); } } diff --git a/block/genhd.c b/block/genhd.c index bfc4148ec341..8c7c32b5dcc0 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -300,7 +300,6 @@ struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector) } } exit: - hd_struct_get(&disk->part0); return &disk->part0; } EXPORT_SYMBOL_GPL(disk_map_sector_rcu);