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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E180C433EF for ; Mon, 27 Dec 2021 03:12:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235102AbhL0DMr (ORCPT ); Sun, 26 Dec 2021 22:12:47 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:15981 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235062AbhL0DMP (ORCPT ); Sun, 26 Dec 2021 22:12:15 -0500 Received: from kwepemi500010.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JMjLL13VSzZdpR; Mon, 27 Dec 2021 11:08:58 +0800 (CST) Received: from kwepemm600013.china.huawei.com (7.193.23.68) by kwepemi500010.china.huawei.com (7.221.188.191) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 27 Dec 2021 11:12:13 +0800 Received: from huawei.com (10.175.127.227) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 27 Dec 2021 11:12:12 +0800 From: Zhihao Cheng To: , , , , , CC: , Subject: [PATCH v6 15/15] ubi: fastmap: Fix high cpu usage of ubi_bgt by making sure wl_pool not empty Date: Mon, 27 Dec 2021 11:22:46 +0800 Message-ID: <20211227032246.2886878-16-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211227032246.2886878-1-chengzhihao1@huawei.com> References: <20211227032246.2886878-1-chengzhihao1@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemm600013.china.huawei.com (7.193.23.68) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There at least 6 PEBs reserved on UBI device: 1. EBA_RESERVED_PEBS[1] 2. WL_RESERVED_PEBS[1] 3. UBI_LAYOUT_VOLUME_EBS[2] 4. MIN_FASTMAP_RESERVED_PEBS[2] When all ubi volumes take all their PEBs, there are 3 (EBA_RESERVED_PEBS + WL_RESERVED_PEBS + MIN_FASTMAP_RESERVED_PEBS - MIN_FASTMAP_TAKEN_PEBS[1]) free PEBs. Since f9c34bb529975fe ("ubi: Fix producing anchor PEBs") and 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs considering wear level rules") applied, there is only 1 (3 - FASTMAP_ANCHOR_PEBS[1] - FASTMAP_NEXT_ANCHOR_PEBS[1]) free PEB to fill pool and wl_pool, after filling pool, wl_pool is always empty. So, UBI could be stuck in an infinite loop: ubi_thread system_wq wear_leveling_worker <-------------------------------------------------- get_peb_for_wl | // fm_wl_pool, used = size = 0 | schedule_work(&ubi->fm_work) | | update_fastmap_work_fn | ubi_update_fastmap | ubi_refill_pools | // ubi->free_count - ubi->beb_rsvd_pebs < 5 | // wl_pool is not filled with any PEBs | schedule_erase(old_fm_anchor) | ubi_ensure_anchor_pebs | __schedule_ubi_work(wear_leveling_worker) | | __erase_worker | ensure_wear_leveling | __schedule_ubi_work(wear_leveling_worker) -------------------------- , which cause high cpu usage of ubi_bgt: top - 12:10:42 up 5 min, 2 users, load average: 1.76, 0.68, 0.27 Tasks: 123 total, 3 running, 54 sleeping, 0 stopped, 0 zombie PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1589 root 20 0 0 0 0 R 45.0 0.0 0:38.86 ubi_bgt0d 319 root 20 0 0 0 0 I 15.2 0.0 0:15.29 kworker/0:3-eve 371 root 20 0 0 0 0 I 14.9 0.0 0:12.85 kworker/3:3-eve 20 root 20 0 0 0 0 I 11.3 0.0 0:05.33 kworker/1:0-eve 202 root 20 0 0 0 0 I 11.3 0.0 0:04.93 kworker/2:3-eve The fm_next_anchor always takes one free PEB to prepare for updating fastmap, fm_anchor and fm_next_anchor are always allocated first of pool and wl_pool, so UBI can regard these two PEBs as reserved PEBs. Fix it by: 1) Adding 2 PEBs reserved for fm_anchor and fm_next_anchor. 2) Abandoning filling wl_pool until free count belows beb_rsvd_pebs. Then, there are at least 2(EBA_RESERVED_PEBS + MIN_FASTMAP_RESERVED_PEBS - MIN_FASTMAP_TAKEN_PEBS[1]) PEBs in pool and 1(WL_RESERVED_PEBS) PEB in wl_pool after calling ubi_refill_pools() with all erase works done. This modification will cause a compatibility problem with old UBI image. If UBI volumes take the maximun number of PEBs for one certain UBI device, there are no available PEBs to satisfy 2 new reserved PEBs, bad reserved PEBs are taken firstly, if still not enough, ENOSPC will returned from ubi initialization. Fetch a reproducer in [Link]. Fixes: f9c34bb529975fe ("ubi: Fix producing anchor PEBs") Fixes: 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs ... rules") Link: https://bugzilla.kernel.org/show_bug.cgi?id=215407 Signed-off-by: Zhihao Cheng --- drivers/mtd/ubi/fastmap-wl.c | 5 +++-- drivers/mtd/ubi/wl.h | 11 +++++++++-- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c index 28f55f9cf715..18f23e76fee9 100644 --- a/drivers/mtd/ubi/fastmap-wl.c +++ b/drivers/mtd/ubi/fastmap-wl.c @@ -134,7 +134,8 @@ void ubi_refill_pools(struct ubi_device *ubi) for (;;) { enough = 0; if (pool->size < pool->max_size) { - if (!ubi->free.rb_node) + if (!ubi->free.rb_node || + (ubi->free_count <= ubi->beb_rsvd_pebs)) break; e = wl_get_wle(ubi); @@ -148,7 +149,7 @@ void ubi_refill_pools(struct ubi_device *ubi) if (wl_pool->size < wl_pool->max_size) { if (!ubi->free.rb_node || - (ubi->free_count - ubi->beb_rsvd_pebs < 5)) + (ubi->free_count <= ubi->beb_rsvd_pebs)) break; e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF); diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h index c93a53293786..e6c8f68d5ffb 100644 --- a/drivers/mtd/ubi/wl.h +++ b/drivers/mtd/ubi/wl.h @@ -2,14 +2,21 @@ #ifndef UBI_WL_H #define UBI_WL_H #ifdef CONFIG_MTD_UBI_FASTMAP + +/* Number of physical eraseblocks for fm anchor */ +#define FASTMAP_ANCHOR_PEBS 1 +/* Number of physical eraseblocks for next fm anchor */ +#define FASTMAP_NEXT_ANCHOR_PEBS 1 + static void update_fastmap_work_fn(struct work_struct *wrk); static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root); static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi); static void ubi_fastmap_close(struct ubi_device *ubi); static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count) { - /* Reserve enough LEBs to store two fastmaps. */ - *count += (ubi->fm_size / ubi->leb_size) * 2; + /* Reserve enough LEBs to store two fastmaps and anchor fm pebs */ + *count += (ubi->fm_size / ubi->leb_size) * 2 + + FASTMAP_ANCHOR_PEBS + FASTMAP_NEXT_ANCHOR_PEBS; INIT_WORK(&ubi->fm_work, update_fastmap_work_fn); } static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi, -- 2.31.1 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7C0FFC433F5 for ; Mon, 27 Dec 2021 03:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:CC:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; 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Mon, 27 Dec 2021 11:12:13 +0800 Received: from huawei.com (10.175.127.227) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Mon, 27 Dec 2021 11:12:12 +0800 From: Zhihao Cheng To: , , , , , CC: , Subject: [PATCH v6 15/15] ubi: fastmap: Fix high cpu usage of ubi_bgt by making sure wl_pool not empty Date: Mon, 27 Dec 2021 11:22:46 +0800 Message-ID: <20211227032246.2886878-16-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211227032246.2886878-1-chengzhihao1@huawei.com> References: <20211227032246.2886878-1-chengzhihao1@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemm600013.china.huawei.com (7.193.23.68) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211226_191215_457502_28D27CDC X-CRM114-Status: GOOD ( 12.26 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org There at least 6 PEBs reserved on UBI device: 1. EBA_RESERVED_PEBS[1] 2. WL_RESERVED_PEBS[1] 3. UBI_LAYOUT_VOLUME_EBS[2] 4. MIN_FASTMAP_RESERVED_PEBS[2] When all ubi volumes take all their PEBs, there are 3 (EBA_RESERVED_PEBS + WL_RESERVED_PEBS + MIN_FASTMAP_RESERVED_PEBS - MIN_FASTMAP_TAKEN_PEBS[1]) free PEBs. Since f9c34bb529975fe ("ubi: Fix producing anchor PEBs") and 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs considering wear level rules") applied, there is only 1 (3 - FASTMAP_ANCHOR_PEBS[1] - FASTMAP_NEXT_ANCHOR_PEBS[1]) free PEB to fill pool and wl_pool, after filling pool, wl_pool is always empty. So, UBI could be stuck in an infinite loop: ubi_thread system_wq wear_leveling_worker <-------------------------------------------------- get_peb_for_wl | // fm_wl_pool, used = size = 0 | schedule_work(&ubi->fm_work) | | update_fastmap_work_fn | ubi_update_fastmap | ubi_refill_pools | // ubi->free_count - ubi->beb_rsvd_pebs < 5 | // wl_pool is not filled with any PEBs | schedule_erase(old_fm_anchor) | ubi_ensure_anchor_pebs | __schedule_ubi_work(wear_leveling_worker) | | __erase_worker | ensure_wear_leveling | __schedule_ubi_work(wear_leveling_worker) -------------------------- , which cause high cpu usage of ubi_bgt: top - 12:10:42 up 5 min, 2 users, load average: 1.76, 0.68, 0.27 Tasks: 123 total, 3 running, 54 sleeping, 0 stopped, 0 zombie PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1589 root 20 0 0 0 0 R 45.0 0.0 0:38.86 ubi_bgt0d 319 root 20 0 0 0 0 I 15.2 0.0 0:15.29 kworker/0:3-eve 371 root 20 0 0 0 0 I 14.9 0.0 0:12.85 kworker/3:3-eve 20 root 20 0 0 0 0 I 11.3 0.0 0:05.33 kworker/1:0-eve 202 root 20 0 0 0 0 I 11.3 0.0 0:04.93 kworker/2:3-eve The fm_next_anchor always takes one free PEB to prepare for updating fastmap, fm_anchor and fm_next_anchor are always allocated first of pool and wl_pool, so UBI can regard these two PEBs as reserved PEBs. Fix it by: 1) Adding 2 PEBs reserved for fm_anchor and fm_next_anchor. 2) Abandoning filling wl_pool until free count belows beb_rsvd_pebs. Then, there are at least 2(EBA_RESERVED_PEBS + MIN_FASTMAP_RESERVED_PEBS - MIN_FASTMAP_TAKEN_PEBS[1]) PEBs in pool and 1(WL_RESERVED_PEBS) PEB in wl_pool after calling ubi_refill_pools() with all erase works done. This modification will cause a compatibility problem with old UBI image. If UBI volumes take the maximun number of PEBs for one certain UBI device, there are no available PEBs to satisfy 2 new reserved PEBs, bad reserved PEBs are taken firstly, if still not enough, ENOSPC will returned from ubi initialization. Fetch a reproducer in [Link]. Fixes: f9c34bb529975fe ("ubi: Fix producing anchor PEBs") Fixes: 4b68bf9a69d22dd ("ubi: Select fastmap anchor PEBs ... rules") Link: https://bugzilla.kernel.org/show_bug.cgi?id=215407 Signed-off-by: Zhihao Cheng --- drivers/mtd/ubi/fastmap-wl.c | 5 +++-- drivers/mtd/ubi/wl.h | 11 +++++++++-- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c index 28f55f9cf715..18f23e76fee9 100644 --- a/drivers/mtd/ubi/fastmap-wl.c +++ b/drivers/mtd/ubi/fastmap-wl.c @@ -134,7 +134,8 @@ void ubi_refill_pools(struct ubi_device *ubi) for (;;) { enough = 0; if (pool->size < pool->max_size) { - if (!ubi->free.rb_node) + if (!ubi->free.rb_node || + (ubi->free_count <= ubi->beb_rsvd_pebs)) break; e = wl_get_wle(ubi); @@ -148,7 +149,7 @@ void ubi_refill_pools(struct ubi_device *ubi) if (wl_pool->size < wl_pool->max_size) { if (!ubi->free.rb_node || - (ubi->free_count - ubi->beb_rsvd_pebs < 5)) + (ubi->free_count <= ubi->beb_rsvd_pebs)) break; e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF); diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h index c93a53293786..e6c8f68d5ffb 100644 --- a/drivers/mtd/ubi/wl.h +++ b/drivers/mtd/ubi/wl.h @@ -2,14 +2,21 @@ #ifndef UBI_WL_H #define UBI_WL_H #ifdef CONFIG_MTD_UBI_FASTMAP + +/* Number of physical eraseblocks for fm anchor */ +#define FASTMAP_ANCHOR_PEBS 1 +/* Number of physical eraseblocks for next fm anchor */ +#define FASTMAP_NEXT_ANCHOR_PEBS 1 + static void update_fastmap_work_fn(struct work_struct *wrk); static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root); static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi); static void ubi_fastmap_close(struct ubi_device *ubi); static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count) { - /* Reserve enough LEBs to store two fastmaps. */ - *count += (ubi->fm_size / ubi->leb_size) * 2; + /* Reserve enough LEBs to store two fastmaps and anchor fm pebs */ + *count += (ubi->fm_size / ubi->leb_size) * 2 + + FASTMAP_ANCHOR_PEBS + FASTMAP_NEXT_ANCHOR_PEBS; INIT_WORK(&ubi->fm_work, update_fastmap_work_fn); } static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi, -- 2.31.1 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/