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 09FFAC433FE for ; Fri, 1 Apr 2022 12:27:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345878AbiDAM3V (ORCPT ); Fri, 1 Apr 2022 08:29:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345876AbiDAM3V (ORCPT ); Fri, 1 Apr 2022 08:29:21 -0400 Received: from mail-m2835.qiye.163.com (mail-m2835.qiye.163.com [103.74.28.35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CFFB278565 for ; Fri, 1 Apr 2022 05:27:31 -0700 (PDT) Received: from localhost.localdomain (unknown [218.94.118.90]) by mail-m2835.qiye.163.com (Hmail) with ESMTPA id 1FCC38A07D6; Fri, 1 Apr 2022 20:27:28 +0800 (CST) From: mingzhe.zou@easystack.cn To: colyli@suse.de, linux-bcache@vger.kernel.org Cc: zoumingzhe@qq.com, ZouMingzhe Subject: [PATCH 1/2] bcache: fixup btree_cache_wait list damage Date: Fri, 1 Apr 2022 20:27:24 +0800 Message-Id: <20220401122725.17725-1-mingzhe.zou@easystack.cn> X-Mailer: git-send-email 2.17.1 X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgPGg8OCBgUHx5ZQUlOS1dZCBgUCR5ZQVlLVUtZV1 kWDxoPAgseWUFZKDYvK1lXWShZQUlCN1dZLVlBSVdZDwkaFQgSH1lBWRpKSUhWHRpMTU4fTBodSk 1LVRkRExYaEhckFA4PWVdZFhoPEhUdFFlBWU9LSFVKSktISkxVS1kG X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6ODY6Tjo*ATIoFExDGDYvDhM2 KzwwFFFVSlVKTU9DQ0pNS09DT0xDVTMWGhIXVRYSFRwBEx5VARQOOx4aCAIIDxoYEFUYFUVZV1kS C1lBWUlKQ1VCT1VKSkNVQktZV1kIAVlBT0JKSzcG X-HM-Tid: 0a7fe518488e841dkuqw1fcc38a07d6 Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org From: ZouMingzhe We get a kernel crash about "list_add corruption. next->prev should be prev (ffff9c801bc01210), but was ffff9c77b688237c. (next=ffffae586d8afe68)." crash> struct list_head 0xffff9c801bc01210 struct list_head { next = 0xffffae586d8afe68, prev = 0xffffae586d8afe68 } crash> struct list_head 0xffff9c77b688237c struct list_head { next = 0x0, prev = 0x0 } crash> struct list_head 0xffffae586d8afe68 struct list_head struct: invalid kernel virtual address: ffffae586d8afe68 type: "gdb_readmem_callback" Cannot access memory at address 0xffffae586d8afe68 [230469.019492] Call Trace: [230469.032041] prepare_to_wait+0x8a/0xb0 [230469.044363] ? bch_btree_keys_free+0x6c/0xc0 [escache] [230469.056533] mca_cannibalize_lock+0x72/0x90 [escache] [230469.068788] mca_alloc+0x2ae/0x450 [escache] [230469.080790] bch_btree_node_get+0x136/0x2d0 [escache] [230469.092681] bch_btree_check_thread+0x1e1/0x260 [escache] [230469.104382] ? finish_wait+0x80/0x80 [230469.115884] ? bch_btree_check_recurse+0x1a0/0x1a0 [escache] [230469.127259] kthread+0x112/0x130 [230469.138448] ? kthread_flush_work_fn+0x10/0x10 [230469.149477] ret_from_fork+0x35/0x40 bch_btree_check_thread() and bch_dirty_init_thread() maybe call mca_cannibalize() to cannibalize other cached btree nodes. Only one thread can do it at a time, so the op of other threads will be added to the btree_cache_wait list. We must call finish_wait() to remove op from btree_cache_wait before free it's memory address. Otherwise, the list will be damaged. Also should call bch_cannibalize_unlock() to release the btree_cache_alloc_lock and wake_up other waiters. Signed-off-by: Mingzhe Zou --- drivers/md/bcache/btree.c | 10 +++++++++- drivers/md/bcache/btree.h | 2 ++ drivers/md/bcache/writeback.c | 8 ++++++++ 3 files changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index ad9f16689419..f8e6f5c7c736 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -885,7 +885,7 @@ static struct btree *mca_cannibalize(struct cache_set *c, struct btree_op *op, * cannibalize_bucket() will take. This means every time we unlock the root of * the btree, we need to release this lock if we have it held. */ -static void bch_cannibalize_unlock(struct cache_set *c) +void bch_cannibalize_unlock(struct cache_set *c) { spin_lock(&c->btree_cannibalize_lock); if (c->btree_cache_alloc_lock == current) { @@ -1968,6 +1968,14 @@ static int bch_btree_check_thread(void *arg) c->gc_stats.nodes++; bch_btree_op_init(&op, 0); ret = bcache_btree(check_recurse, p, c->root, &op); + /* The op may be added to cache_set's btree_cache_wait + * in mca_cannibalize(), must ensure it is removed from + * the list and release btree_cache_alloc_lock before + * free op memory. + * Otherwise, the btree_cache_wait will be damaged. + */ + bch_cannibalize_unlock(c); + finish_wait(&c->btree_cache_wait, &(&op)->wait); if (ret) goto out; } diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h index 50482107134f..435e82574ac3 100644 --- a/drivers/md/bcache/btree.h +++ b/drivers/md/bcache/btree.h @@ -365,6 +365,8 @@ static inline void force_wake_up_gc(struct cache_set *c) _r; \ }) +void bch_cannibalize_unlock(struct cache_set *c); + #define MAP_DONE 0 #define MAP_CONTINUE 1 diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 9ee0005874cd..5b828555bca8 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -865,6 +865,14 @@ static int bch_root_node_dirty_init(struct cache_set *c, } } while (ret == -EAGAIN); + /* The op may be added to cache_set's btree_cache_wait + * in mca_cannibalize(), must ensure it is removed from + * the list and release btree_cache_alloc_lock before + * free op memory. + * Otherwise, the btree_cache_wait will be damaged. + */ + bch_cannibalize_unlock(c); + finish_wait(&c->btree_cache_wait, &(&op.op)->wait); return ret; } -- 2.17.1