From patchwork Tue Oct 19 02:41:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12568501 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF966C433EF for ; Tue, 19 Oct 2021 02:29:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFC2D611BF for ; Tue, 19 Oct 2021 02:29:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229839AbhJSCbO (ORCPT ); Mon, 18 Oct 2021 22:31:14 -0400 Received: from szxga08-in.huawei.com ([45.249.212.255]:25165 "EHLO szxga08-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229733AbhJSCbN (ORCPT ); Mon, 18 Oct 2021 22:31:13 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4HYHh26nmxz1DHbH; Tue, 19 Oct 2021 10:27:14 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.15; Tue, 19 Oct 2021 10:28:57 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.15; Tue, 19 Oct 2021 10:28:56 +0800 From: Yu Kuai To: , , , , CC: , , , , Subject: [PATCH v3 -next 1/2] blk-cgroup: don't call blk_mq_freeze_queue() in blkcg_deactivate_policy() Date: Tue, 19 Oct 2021 10:41:31 +0800 Message-ID: <20211019024132.432458-2-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211019024132.432458-1-yukuai3@huawei.com> References: <20211019024132.432458-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org blkcg_deactivate_policy() can be called from either blk_cleanup_queue() for all policies or elevator_switch() for bfq policy. Thus there is no need to freeze queue in blkcg_deactivate_policy() since the caller freeze the queue aready. Signed-off-by: Yu Kuai --- block/blk-cgroup.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index cec86a705c89..ca60233c8392 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1398,9 +1398,6 @@ void blkcg_deactivate_policy(struct request_queue *q, if (!blkcg_policy_enabled(q, pol)) return; - if (queue_is_mq(q)) - blk_mq_freeze_queue(q); - spin_lock_irq(&q->queue_lock); __clear_bit(pol->plid, q->blkcg_pols); @@ -1419,9 +1416,6 @@ void blkcg_deactivate_policy(struct request_queue *q, } spin_unlock_irq(&q->queue_lock); - - if (queue_is_mq(q)) - blk_mq_unfreeze_queue(q); } EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); From patchwork Tue Oct 19 02:41:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12568503 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF1D9C433F5 for ; Tue, 19 Oct 2021 02:29:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2AAA610A1 for ; Tue, 19 Oct 2021 02:29:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231772AbhJSCbS (ORCPT ); Mon, 18 Oct 2021 22:31:18 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:14826 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231479AbhJSCbR (ORCPT ); Mon, 18 Oct 2021 22:31:17 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HYHcS0hhCz90Jb; Tue, 19 Oct 2021 10:24:08 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.15; Tue, 19 Oct 2021 10:28:58 +0800 Received: from huawei.com (10.175.127.227) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.15; Tue, 19 Oct 2021 10:28:57 +0800 From: Yu Kuai To: , , , , CC: , , , , Subject: [PATCH v3 -next 2/2] blk-cgroup: synchoronize blkg creation against policy deactivation Date: Tue, 19 Oct 2021 10:41:32 +0800 Message-ID: <20211019024132.432458-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211019024132.432458-1-yukuai3@huawei.com> References: <20211019024132.432458-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Out test report a null pointer dereference: [ 168.534653] ================================================================== [ 168.535614] Disabling lock debugging due to kernel taint [ 168.536346] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 168.537274] #PF: supervisor read access in kernel mode [ 168.537964] #PF: error_code(0x0000) - not-present page [ 168.538667] PGD 0 P4D 0 [ 168.539025] Oops: 0000 [#1] PREEMPT SMP KASAN [ 168.539656] CPU: 13 PID: 759 Comm: bash Tainted: G B 5.15.0-rc2-next-202100 [ 168.540954] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_0738364 [ 168.542736] RIP: 0010:bfq_pd_init+0x88/0x1e0 [ 168.543318] Code: 98 00 00 00 e8 c9 e4 5b ff 4c 8b 65 00 49 8d 7c 24 08 e8 bb e4 5b ff 4d0 [ 168.545803] RSP: 0018:ffff88817095f9c0 EFLAGS: 00010002 [ 168.546497] RAX: 0000000000000001 RBX: ffff888101a1c000 RCX: 0000000000000000 [ 168.547438] RDX: 0000000000000003 RSI: 0000000000000002 RDI: ffff888106553428 [ 168.548402] RBP: ffff888106553400 R08: ffffffff961bcaf4 R09: 0000000000000001 [ 168.549365] R10: ffffffffa2e16c27 R11: fffffbfff45c2d84 R12: 0000000000000000 [ 168.550291] R13: ffff888101a1c098 R14: ffff88810c7a08c8 R15: ffffffffa55541a0 [ 168.551221] FS: 00007fac75227700(0000) GS:ffff88839ba80000(0000) knlGS:0000000000000000 [ 168.552278] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 168.553040] CR2: 0000000000000008 CR3: 0000000165ce7000 CR4: 00000000000006e0 [ 168.554000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 168.554929] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 168.555888] Call Trace: [ 168.556221] [ 168.556510] blkg_create+0x1c0/0x8c0 [ 168.556989] blkg_conf_prep+0x574/0x650 [ 168.557502] ? stack_trace_save+0x99/0xd0 [ 168.558033] ? blkcg_conf_open_bdev+0x1b0/0x1b0 [ 168.558629] tg_set_conf.constprop.0+0xb9/0x280 [ 168.559231] ? kasan_set_track+0x29/0x40 [ 168.559758] ? kasan_set_free_info+0x30/0x60 [ 168.560344] ? tg_set_limit+0xae0/0xae0 [ 168.560853] ? do_sys_openat2+0x33b/0x640 [ 168.561383] ? do_sys_open+0xa2/0x100 [ 168.561877] ? __x64_sys_open+0x4e/0x60 [ 168.562383] ? __kasan_check_write+0x20/0x30 [ 168.562951] ? copyin+0x48/0x70 [ 168.563390] ? _copy_from_iter+0x234/0x9e0 [ 168.563948] tg_set_conf_u64+0x17/0x20 [ 168.564467] cgroup_file_write+0x1ad/0x380 [ 168.565014] ? cgroup_file_poll+0x80/0x80 [ 168.565568] ? __mutex_lock_slowpath+0x30/0x30 [ 168.566165] ? pgd_free+0x100/0x160 [ 168.566649] kernfs_fop_write_iter+0x21d/0x340 [ 168.567246] ? cgroup_file_poll+0x80/0x80 [ 168.567796] new_sync_write+0x29f/0x3c0 [ 168.568314] ? new_sync_read+0x410/0x410 [ 168.568840] ? __handle_mm_fault+0x1c97/0x2d80 [ 168.569425] ? copy_page_range+0x2b10/0x2b10 [ 168.570007] ? _raw_read_lock_bh+0xa0/0xa0 [ 168.570622] vfs_write+0x46e/0x630 [ 168.571091] ksys_write+0xcd/0x1e0 [ 168.571563] ? __x64_sys_read+0x60/0x60 [ 168.572081] ? __kasan_check_write+0x20/0x30 [ 168.572659] ? do_user_addr_fault+0x446/0xff0 [ 168.573264] __x64_sys_write+0x46/0x60 [ 168.573774] do_syscall_64+0x35/0x80 [ 168.574264] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 168.574960] RIP: 0033:0x7fac74915130 [ 168.575456] Code: 73 01 c3 48 8b 0d 58 ed 2c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 444 [ 168.577969] RSP: 002b:00007ffc3080e288 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 168.578986] RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007fac74915130 [ 168.579937] RDX: 0000000000000009 RSI: 000056007669f080 RDI: 0000000000000001 [ 168.580884] RBP: 000056007669f080 R08: 000000000000000a R09: 00007fac75227700 [ 168.581841] R10: 000056007655c8f0 R11: 0000000000000246 R12: 0000000000000009 [ 168.582796] R13: 0000000000000001 R14: 00007fac74be55e0 R15: 00007fac74be08c0 [ 168.583757] [ 168.584063] Modules linked in: [ 168.584494] CR2: 0000000000000008 [ 168.584964] ---[ end trace 2475611ad0f77a1a ]--- This is because blkg_alloc() is called from blkg_conf_prep() without holding 'q->queue_lock', and elevator is exited before blkg_create(): thread 1 thread 2 blkg_conf_prep spin_lock_irq(&q->queue_lock); blkg_lookup_check -> return NULL spin_unlock_irq(&q->queue_lock); blkg_alloc blkcg_policy_enabled -> true pd = ->pd_alloc_fn blkg->pd[i] = pd blk_mq_exit_sched bfq_exit_queue blkcg_deactivate_policy spin_lock_irq(&q->queue_lock); __clear_bit(pol->plid, q->blkcg_pols); spin_unlock_irq(&q->queue_lock); q->elevator = NULL; spin_lock_irq(&q->queue_lock); blkg_create if (blkg->pd[i]) ->pd_init_fn -> q->elevator is NULL spin_unlock_irq(&q->queue_lock); Because blkcg_deactivate_policy() require queue to be freezed, thus grab q_usage_counter to synchoronize blkg_conf_prep() against blkcg_deactivate_policy(). Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Yu Kuai Acked-by: Tejun Heo --- block/blk-cgroup.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index ca60233c8392..e11b7e28b1b2 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -634,6 +634,14 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, q = bdev_get_queue(bdev); + /* + * blkcg_deactivate_policy() require queue to be freezed, thus grab + * q_usage_counter to prevent concurrent with blkcg_deactivate_policy(). + */ + ret = blk_queue_enter(q, 0); + if (ret) + return ret; + rcu_read_lock(); spin_lock_irq(&q->queue_lock); @@ -703,6 +711,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, goto success; } success: + blk_queue_exit(q); ctx->bdev = bdev; ctx->blkg = blkg; ctx->body = input; @@ -715,6 +724,7 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, rcu_read_unlock(); fail: blkdev_put_no_open(bdev); + blk_queue_exit(q); /* * If queue was bypassing, we should retry. Do so after a * short msleep(). It isn't strictly necessary but queue