From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E2B2C2D0A3 for ; Mon, 9 Nov 2020 10:24:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DA86A206B2 for ; Mon, 9 Nov 2020 10:24:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604917479; bh=zYcMHIKo2Cf5RbooHK/TsMZjRH0PB1xdljGDJ8hURZ4=; h=Subject:To:Cc:From:Date:List-ID:From; b=X10YTR5xuNJWMD0xyj8kWY3A6wILQ3Enx0kGDAYX9u3gRBxZoGFax2w+mrQcmOQlN /3Fypv1Bek+aOOHbdY1FC5c7JqBV2f4PCfL7lYYR0I6WXTr+HjZdbzmvum5ekzCT0j gZ1qogJ5SBWi0YZPd9mtVSe+J3M/Za64ei8XHaEk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726535AbgKIKYj (ORCPT ); Mon, 9 Nov 2020 05:24:39 -0500 Received: from wforward3-smtp.messagingengine.com ([64.147.123.22]:60421 "EHLO wforward3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726176AbgKIKYj (ORCPT ); Mon, 9 Nov 2020 05:24:39 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.west.internal (Postfix) with ESMTP id 56820116E; Mon, 9 Nov 2020 05:24:38 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Mon, 09 Nov 2020 05:24:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=Edn5pN SXr/dru602f3zkCMU5v2L8bukCcUyLHUm5ogA=; b=b26i+MyFKOXnPgnYO2ikOL v6tAqi37SmfjvalBMzKK4PPTWVJC6D+J0hnQBg7nJ5fXg9zkX6jGd9op4ag1fzsO /X0wp784qBVMGw0HnecqyoroOvM2dZ6OEiA1EhoLQCyn/E+ZKomDhbxBjxLLTN8Z kfY6heu6Aah8Ww+F0zPvlJen9ngN7xb4brSFAf+B/QBaLihAe7nfx620RqiXoGWo vslxH7xWhjSGUaaOYp1EGQfLkt4WKoL53EsSc4MeZyT66UaQmOEm5sr/mQxh0LQ0 NEaKXSQrO9RLoZl5A/o1tmpDkd8UfD2wWX1ApvLyeM3flo/kAViwS0OXEk9VGtiw == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedrudduhedgudeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepieetveehuedvhfdtgfdvieeiheehfeelveevheejud etveeuveeludejjefgteehnecukfhppeekfedrkeeirdejgedrieegnecuvehluhhsthgv rhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghhrd gtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 0ED4B328005D; Mon, 9 Nov 2020 05:24:36 -0500 (EST) Subject: FAILED: patch "[PATCH] null_blk: Fix scheduling in atomic with zoned mode" failed to apply to 5.9-stable tree To: damien.lemoal@wdc.com, axboe@kernel.dk, hch@lst.de, lkp@intel.com Cc: From: Date: Mon, 09 Nov 2020 11:25:37 +0100 Message-ID: <160491753798199@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e1777d099728a76a8f8090f89649aac961e7e530 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Fri, 6 Nov 2020 20:01:41 +0900 Subject: [PATCH] null_blk: Fix scheduling in atomic with zoned mode Commit aa1c09cb65e2 ("null_blk: Fix locking in zoned mode") changed zone locking to using the potentially sleeping wait_on_bit_io() function. This is acceptable when memory backing is enabled as the device queue is in that case marked as blocking, but this triggers a scheduling while in atomic context with memory backing disabled. Fix this by relying solely on the device zone spinlock for zone information protection without temporarily releasing this lock around null_process_cmd() execution in null_zone_write(). This is OK to do since when memory backing is disabled, command processing does not block and the memory backing lock nullb->lock is unused. This solution avoids the overhead of having to mark a zoned null_blk device queue as blocking when memory backing is unused. This patch also adds comments to the zone locking code to explain the unusual locking scheme. Fixes: aa1c09cb65e2 ("null_blk: Fix locking in zoned mode") Reported-by: kernel test robot Signed-off-by: Damien Le Moal Reviewed-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe diff --git a/drivers/block/null_blk.h b/drivers/block/null_blk.h index cfd00ad40355..c24d9b5ad81a 100644 --- a/drivers/block/null_blk.h +++ b/drivers/block/null_blk.h @@ -47,7 +47,7 @@ struct nullb_device { unsigned int nr_zones_closed; struct blk_zone *zones; sector_t zone_size_sects; - spinlock_t zone_dev_lock; + spinlock_t zone_lock; unsigned long *zone_locks; unsigned long size; /* device size in MB */ diff --git a/drivers/block/null_blk_zoned.c b/drivers/block/null_blk_zoned.c index 8775acbb4f8f..beb34b4f76b0 100644 --- a/drivers/block/null_blk_zoned.c +++ b/drivers/block/null_blk_zoned.c @@ -46,11 +46,20 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q) if (!dev->zones) return -ENOMEM; - spin_lock_init(&dev->zone_dev_lock); - dev->zone_locks = bitmap_zalloc(dev->nr_zones, GFP_KERNEL); - if (!dev->zone_locks) { - kvfree(dev->zones); - return -ENOMEM; + /* + * With memory backing, the zone_lock spinlock needs to be temporarily + * released to avoid scheduling in atomic context. To guarantee zone + * information protection, use a bitmap to lock zones with + * wait_on_bit_lock_io(). Sleeping on the lock is OK as memory backing + * implies that the queue is marked with BLK_MQ_F_BLOCKING. + */ + spin_lock_init(&dev->zone_lock); + if (dev->memory_backed) { + dev->zone_locks = bitmap_zalloc(dev->nr_zones, GFP_KERNEL); + if (!dev->zone_locks) { + kvfree(dev->zones); + return -ENOMEM; + } } if (dev->zone_nr_conv >= dev->nr_zones) { @@ -137,12 +146,17 @@ void null_free_zoned_dev(struct nullb_device *dev) static inline void null_lock_zone(struct nullb_device *dev, unsigned int zno) { - wait_on_bit_lock_io(dev->zone_locks, zno, TASK_UNINTERRUPTIBLE); + if (dev->memory_backed) + wait_on_bit_lock_io(dev->zone_locks, zno, TASK_UNINTERRUPTIBLE); + spin_lock_irq(&dev->zone_lock); } static inline void null_unlock_zone(struct nullb_device *dev, unsigned int zno) { - clear_and_wake_up_bit(zno, dev->zone_locks); + spin_unlock_irq(&dev->zone_lock); + + if (dev->memory_backed) + clear_and_wake_up_bit(zno, dev->zone_locks); } int null_report_zones(struct gendisk *disk, sector_t sector, @@ -322,7 +336,6 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector, return null_process_cmd(cmd, REQ_OP_WRITE, sector, nr_sectors); null_lock_zone(dev, zno); - spin_lock(&dev->zone_dev_lock); switch (zone->cond) { case BLK_ZONE_COND_FULL: @@ -375,9 +388,17 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector, if (zone->cond != BLK_ZONE_COND_EXP_OPEN) zone->cond = BLK_ZONE_COND_IMP_OPEN; - spin_unlock(&dev->zone_dev_lock); + /* + * Memory backing allocation may sleep: release the zone_lock spinlock + * to avoid scheduling in atomic context. Zone operation atomicity is + * still guaranteed through the zone_locks bitmap. + */ + if (dev->memory_backed) + spin_unlock_irq(&dev->zone_lock); ret = null_process_cmd(cmd, REQ_OP_WRITE, sector, nr_sectors); - spin_lock(&dev->zone_dev_lock); + if (dev->memory_backed) + spin_lock_irq(&dev->zone_lock); + if (ret != BLK_STS_OK) goto unlock; @@ -392,7 +413,6 @@ static blk_status_t null_zone_write(struct nullb_cmd *cmd, sector_t sector, ret = BLK_STS_OK; unlock: - spin_unlock(&dev->zone_dev_lock); null_unlock_zone(dev, zno); return ret; @@ -516,9 +536,7 @@ static blk_status_t null_zone_mgmt(struct nullb_cmd *cmd, enum req_opf op, null_lock_zone(dev, i); zone = &dev->zones[i]; if (zone->cond != BLK_ZONE_COND_EMPTY) { - spin_lock(&dev->zone_dev_lock); null_reset_zone(dev, zone); - spin_unlock(&dev->zone_dev_lock); trace_nullb_zone_op(cmd, i, zone->cond); } null_unlock_zone(dev, i); @@ -530,7 +548,6 @@ static blk_status_t null_zone_mgmt(struct nullb_cmd *cmd, enum req_opf op, zone = &dev->zones[zone_no]; null_lock_zone(dev, zone_no); - spin_lock(&dev->zone_dev_lock); switch (op) { case REQ_OP_ZONE_RESET: @@ -550,8 +567,6 @@ static blk_status_t null_zone_mgmt(struct nullb_cmd *cmd, enum req_opf op, break; } - spin_unlock(&dev->zone_dev_lock); - if (ret == BLK_STS_OK) trace_nullb_zone_op(cmd, zone_no, zone->cond);