From patchwork Tue Jan 24 14:06:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikulas Patocka X-Patchwork-Id: 13114187 X-Patchwork-Delegate: song@kernel.org 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60AD1C25B4E for ; Tue, 24 Jan 2023 14:07:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233090AbjAXOHy (ORCPT ); Tue, 24 Jan 2023 09:07:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233967AbjAXOHx (ORCPT ); Tue, 24 Jan 2023 09:07:53 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC1272942F for ; Tue, 24 Jan 2023 06:06:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674569213; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=BJ8F5TngKPojOlGsdqi4nx7smy2E7/8+bokHr9VxWAY=; b=D1Fqr7MHfJXSDwynMtR8Mo12K6XXYIJDB95CrVPFXJeToVlFJbF1rxFTSI/dvZ8BWBFXG/ n7XxLUyPAhqB2ynhpbJ4m+tznJn36yNtv+V5mbqAKDO+CqNnehy2UFZuWJZ7ETQH7k6ENp 2RqlqGbId50fjuK4oASLRjOwb+u5aVc= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-668-09m3n2xNMMekUmFjUB_uRA-1; Tue, 24 Jan 2023 09:06:46 -0500 X-MC-Unique: 09m3n2xNMMekUmFjUB_uRA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B183B3811F2C; Tue, 24 Jan 2023 14:06:45 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A40F340C2004; Tue, 24 Jan 2023 14:06:45 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 30OE6jhd010122; Tue, 24 Jan 2023 09:06:45 -0500 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 30OE6jqW010118; Tue, 24 Jan 2023 09:06:45 -0500 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Tue, 24 Jan 2023 09:06:45 -0500 (EST) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Song Liu cc: linux-raid@vger.kernel.org, dm-devel@redhat.com Subject: [PATCH] md: use preallocated hashed wait queues instead of mddev->sb_wait Message-ID: User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org There's a theoretical race condition in md. super_written calls: if (atomic_dec_and_test(&mddev->pending_writes)) wake_up(&mddev->sb_wait); If the process is rescheduled just after atomic_dec_and_test and before wake_up, it may happen that the mddev structure is freed (because mddev->pending_writes is zero) and on scheduling back, wake_up(&mddev->sb_wait) would access freed memory. Fix this bug by using an array of preallocated wait_queues, so that the wait queue exist even after mddev was freed. Signed-off-by: Mikulas Patocka --- drivers/md/md.c | 56 ++++++++++++++++++++++++++--------------------- drivers/md/md.h | 10 +++++++- drivers/md/raid10.c | 4 +-- drivers/md/raid5-cache.c | 6 ++--- drivers/md/raid5.c | 8 +++--- 5 files changed, 49 insertions(+), 35 deletions(-) Index: linux-2.6/drivers/md/md.c =================================================================== --- linux-2.6.orig/drivers/md/md.c +++ linux-2.6/drivers/md/md.c @@ -89,6 +89,9 @@ static struct workqueue_struct *md_wq; static struct workqueue_struct *md_misc_wq; static struct workqueue_struct *md_rdev_misc_wq; +wait_queue_head_t md_sb_wait_table[MD_SB_WAIT_TABLE_SIZE]; +EXPORT_SYMBOL(md_sb_wait_table); + static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *this); static void mddev_detach(struct mddev *mddev); @@ -415,7 +418,7 @@ check_suspended: return; } for (;;) { - prepare_to_wait(&mddev->sb_wait, &__wait, + prepare_to_wait(md_sb_wait(mddev), &__wait, TASK_UNINTERRUPTIBLE); if (!is_suspended(mddev, bio)) break; @@ -423,19 +426,19 @@ check_suspended: schedule(); rcu_read_lock(); } - finish_wait(&mddev->sb_wait, &__wait); + finish_wait(md_sb_wait(mddev), &__wait); } atomic_inc(&mddev->active_io); rcu_read_unlock(); if (!mddev->pers->make_request(mddev, bio)) { atomic_dec(&mddev->active_io); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); goto check_suspended; } if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended) - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); } EXPORT_SYMBOL(md_handle_request); @@ -484,13 +487,13 @@ void mddev_suspend(struct mddev *mddev) if (mddev->suspended++) return; synchronize_rcu(); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); set_bit(MD_ALLOW_SB_UPDATE, &mddev->flags); smp_mb__after_atomic(); - wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0); + wait_event(*md_sb_wait(mddev), atomic_read(&mddev->active_io) == 0); mddev->pers->quiesce(mddev, 1); clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags); - wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags)); + wait_event(*md_sb_wait(mddev), !test_bit(MD_UPDATING_SB, &mddev->flags)); del_timer_sync(&mddev->safemode_timer); /* restrict memory reclaim I/O during raid array is suspend */ @@ -505,7 +508,7 @@ void mddev_resume(struct mddev *mddev) lockdep_assert_held(&mddev->reconfig_mutex); if (--mddev->suspended) return; - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); mddev->pers->quiesce(mddev, 0); set_bit(MD_RECOVERY_NEEDED, &mddev->recovery); @@ -585,7 +588,7 @@ static void md_submit_flush_data(struct mddev->prev_flush_start = mddev->start_flush; mddev->flush_bio = NULL; spin_unlock_irq(&mddev->lock); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); if (bio->bi_iter.bi_size == 0) { /* an empty barrier - all done */ @@ -609,7 +612,7 @@ bool md_flush_request(struct mddev *mdde /* flush requests wait until ongoing flush completes, * hence coalescing all the pending requests. */ - wait_event_lock_irq(mddev->sb_wait, + wait_event_lock_irq(*md_sb_wait(mddev), !mddev->flush_bio || ktime_before(req_start, mddev->prev_flush_start), mddev->lock); @@ -686,7 +689,6 @@ void mddev_init(struct mddev *mddev) atomic_set(&mddev->active_io, 0); spin_lock_init(&mddev->lock); atomic_set(&mddev->flush_pending, 0); - init_waitqueue_head(&mddev->sb_wait); init_waitqueue_head(&mddev->recovery_wait); mddev->reshape_position = MaxSector; mddev->reshape_backwards = 0; @@ -828,7 +830,7 @@ void mddev_unlock(struct mddev *mddev) */ spin_lock(&pers_lock); md_wakeup_thread(mddev->thread); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); spin_unlock(&pers_lock); } EXPORT_SYMBOL_GPL(mddev_unlock); @@ -933,7 +935,7 @@ static void super_written(struct bio *bi rdev_dec_pending(rdev, mddev); if (atomic_dec_and_test(&mddev->pending_writes)) - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); } void md_super_write(struct mddev *mddev, struct md_rdev *rdev, @@ -977,7 +979,7 @@ void md_super_write(struct mddev *mddev, int md_super_wait(struct mddev *mddev) { /* wait for all superblock writes that were scheduled to complete */ - wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0); + wait_event(*md_sb_wait(mddev), atomic_read(&mddev->pending_writes)==0); if (test_and_clear_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags)) return -EAGAIN; return 0; @@ -2681,7 +2683,7 @@ repeat: wake_up(&rdev->blocked_wait); } } - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); return; } @@ -2791,7 +2793,7 @@ rewrite: BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_CLEAN))) /* have to write it out again */ goto repeat; - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) sysfs_notify_dirent_safe(mddev->sysfs_completed); @@ -4383,7 +4385,7 @@ array_state_store(struct mddev *mddev, c restart_array(mddev); clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags); md_wakeup_thread(mddev->thread); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); } else /* st == clean */ { restart_array(mddev); if (!set_in_sync(mddev)) @@ -4456,7 +4458,7 @@ array_state_store(struct mddev *mddev, c if (err) break; clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); err = 0; } else { mddev->ro = MD_RDWR; @@ -6283,7 +6285,7 @@ static int md_set_readonly(struct mddev mddev_unlock(mddev); wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)); - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); mddev_lock_nointr(mddev); @@ -7564,7 +7566,7 @@ static int md_ioctl(struct block_device if (cmd == HOT_REMOVE_DISK) /* need to ensure recovery thread has run */ - wait_event_interruptible_timeout(mddev->sb_wait, + wait_event_interruptible_timeout(*md_sb_wait(mddev), !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery), msecs_to_jiffies(5000)); @@ -7669,7 +7671,7 @@ static int md_ioctl(struct block_device */ if (test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)) { mddev_unlock(mddev); - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags) && !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); mddev_lock_nointr(mddev); @@ -8529,7 +8531,7 @@ bool md_write_start(struct mddev *mddev, sysfs_notify_dirent_safe(mddev->sysfs_state); if (!mddev->has_superblocks) return true; - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) || mddev->suspended); if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) { @@ -8674,7 +8676,7 @@ void md_allow_write(struct mddev *mddev) md_update_sb(mddev, 0); sysfs_notify_dirent_safe(mddev->sysfs_state); /* wait for the dirty state to be recorded in the metadata */ - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); } else spin_unlock(&mddev->lock); @@ -9256,7 +9258,7 @@ void md_check_recovery(struct mddev *mdd if (test_bit(MD_ALLOW_SB_UPDATE, &mddev->flags)) md_update_sb(mddev, 0); clear_bit_unlock(MD_UPDATING_SB, &mddev->flags); - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); } if (mddev->suspended) @@ -9420,7 +9422,7 @@ void md_check_recovery(struct mddev *mdd sysfs_notify_dirent_safe(mddev->sysfs_action); } unlock: - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); mddev_unlock(mddev); } } @@ -9608,6 +9610,10 @@ static void md_geninit(void) static int __init md_init(void) { int ret = -ENOMEM; + int i; + + for (i = 0; i < MD_SB_WAIT_TABLE_SIZE; i++) + init_waitqueue_head(md_sb_wait_table + i); md_wq = alloc_workqueue("md", WQ_MEM_RECLAIM, 0); if (!md_wq) Index: linux-2.6/drivers/md/md.h =================================================================== --- linux-2.6.orig/drivers/md/md.h +++ linux-2.6/drivers/md/md.h @@ -466,7 +466,6 @@ struct mddev { * setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max}) */ spinlock_t lock; - wait_queue_head_t sb_wait; /* for waiting on superblock updates */ atomic_t pending_writes; /* number of active superblock writes */ unsigned int safemode; /* if set, update "clean" superblock @@ -584,6 +583,15 @@ static inline void md_sync_acct_bio(stru md_sync_acct(bio->bi_bdev, nr_sectors); } +#define MD_SB_WAIT_TABLE_BITS 8 +#define MD_SB_WAIT_TABLE_SIZE (1U << MD_SB_WAIT_TABLE_BITS) +extern wait_queue_head_t md_sb_wait_table[MD_SB_WAIT_TABLE_SIZE]; + +static inline wait_queue_head_t *md_sb_wait(struct mddev *md) +{ + return md_sb_wait_table + hash_long((unsigned long)md, MD_SB_WAIT_TABLE_BITS); +} + struct md_personality { char *name; Index: linux-2.6/drivers/md/raid10.c =================================================================== --- linux-2.6.orig/drivers/md/raid10.c +++ linux-2.6/drivers/md/raid10.c @@ -1446,7 +1446,7 @@ static void raid10_write_request(struct return; } raid10_log(conf->mddev, "wait reshape metadata"); - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)); conf->reshape_safe = mddev->reshape_position; @@ -4876,7 +4876,7 @@ static sector_t reshape_request(struct m conf->reshape_checkpoint = jiffies; set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags); md_wakeup_thread(mddev->thread); - wait_event(mddev->sb_wait, mddev->sb_flags == 0 || + wait_event(*md_sb_wait(mddev), mddev->sb_flags == 0 || test_bit(MD_RECOVERY_INTR, &mddev->recovery)); if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) { allow_barrier(conf); Index: linux-2.6/drivers/md/raid5-cache.c =================================================================== --- linux-2.6.orig/drivers/md/raid5-cache.c +++ linux-2.6/drivers/md/raid5-cache.c @@ -691,7 +691,7 @@ static void r5c_disable_writeback_async( mdname(mddev)); /* wait superblock change before suspend */ - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), conf->log == NULL || (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && (locked = mddev_trylock(mddev)))); @@ -1581,7 +1581,7 @@ void r5l_quiesce(struct r5l_log *log, in if (quiesce) { /* make sure r5l_write_super_and_discard_space exits */ mddev = log->rdev->mddev; - wake_up(&mddev->sb_wait); + wake_up_all(md_sb_wait(mddev)); kthread_park(log->reclaim_thread->tsk); r5l_wake_reclaim(log, MaxSector); r5l_do_reclaim(log); @@ -3165,7 +3165,7 @@ void r5l_exit_log(struct r5conf *conf) struct r5l_log *log = conf->log; /* Ensure disable_writeback_work wakes up and exits */ - wake_up(&conf->mddev->sb_wait); + wake_up_all(md_sb_wait(conf->mddev)); flush_work(&log->disable_writeback_work); md_unregister_thread(&log->reclaim_thread); Index: linux-2.6/drivers/md/raid5.c =================================================================== --- linux-2.6.orig/drivers/md/raid5.c +++ linux-2.6/drivers/md/raid5.c @@ -6346,7 +6346,7 @@ static sector_t reshape_request(struct m conf->reshape_checkpoint = jiffies; set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags); md_wakeup_thread(mddev->thread); - wait_event(mddev->sb_wait, mddev->sb_flags == 0 || + wait_event(*md_sb_wait(mddev), mddev->sb_flags == 0 || test_bit(MD_RECOVERY_INTR, &mddev->recovery)); if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) return 0; @@ -6454,7 +6454,7 @@ finish: conf->reshape_checkpoint = jiffies; set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags); md_wakeup_thread(mddev->thread); - wait_event(mddev->sb_wait, + wait_event(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags) || test_bit(MD_RECOVERY_INTR, &mddev->recovery)); if (test_bit(MD_RECOVERY_INTR, &mddev->recovery)) @@ -6703,7 +6703,7 @@ static void raid5_do_work(struct work_st if (!batch_size && !released) break; handled += batch_size; - wait_event_lock_irq(mddev->sb_wait, + wait_event_lock_irq(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags), conf->device_lock); } @@ -6792,7 +6792,7 @@ static void raid5d(struct md_thread *thr continue; } - wait_event_lock_irq(mddev->sb_wait, + wait_event_lock_irq(*md_sb_wait(mddev), !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags), conf->device_lock); }