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Date: Mon, 30 Nov 2020 19:21:37 +0800
From: Yi Li <yili@...hong.com>
To: colyli@...e.de
Cc: yilikernel@...il.com, kent.overstreet@...il.com,
linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
Yi Li <yili@...hong.com>, Guo Chao <guochao@...hong.com>
Subject: [PATCH] bcache: fix panic due to cache_set is null
bcache_device_detach will release the cache_set after hotunplug cache
disk. update_writeback_rate should check validate of cache_set.
IP: [<ffffffffa03730c9>] update_writeback_rate+0x59/0x3a0 [bcache]
PGD 879620067 PUD 8755d3067 PMD 0
Oops: 0000 [#1] SMP
CPU: 8 PID: 1005702 Comm: kworker/8:0 Tainted: G 4.4.0+10 #1
Hardware name: Intel BIOS SE5C610.86B.01.01.0021.032120170601 03/21/2017
Workqueue: events update_writeback_rate [bcache]
task: ffff8808786f3800 ti: ffff88077082c000 task.ti: ffff88077082c000
RIP: e030:[<ffffffffa03730c9>] update_writeback_rate+0x59/0x3a0 [bcache]
RSP: e02b:ffff88077082fde0 EFLAGS: 00010202
RAX: 0000000000000018 RBX: ffff8808047f0b08 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff88088170dab8 RDI: ffff88088170dab8
RBP: ffff88077082fe18 R08: 000000000000000a R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000017bc8 R12: 0000000000000000
R13: ffff8808047f0000 R14: 0000000000000200 R15: ffff8808047f0b08
FS: 00007f157b6d6700(0000) GS:ffff880881700000(0000) knlGS:0000000000000000
CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000368 CR3: 0000000875c05000 CR4: 0000000000040660
Stack:
0000000000000001 0000000000007ff0 ffff88085ff600c0 ffff880881714e80
ffff880881719500 0000000000000200 ffff8808047f0b08 ffff88077082fe60
ffffffff81088c0c 0000000081714e80 0000000000000000 ffff880881714e80
Call Trace:
[<ffffffff81088c0c>] process_one_work+0x1fc/0x3b0
[<ffffffff81089575>] worker_thread+0x2a5/0x470
[<ffffffff815a2f58>] ? __schedule+0x648/0x870
[<ffffffff810892d0>] ? rescuer_thread+0x300/0x300
[<ffffffff8108e3d5>] kthread+0xd5/0xe0
[<ffffffff8108e300>] ? kthread_stop+0x110/0x110
[<ffffffff815a704f>] ret_from_fork+0x3f/0x70
[<ffffffff8108e300>] ? kthread_stop+0x110/0x110
Reported-by: Guo Chao <guochao@...hong.com>
Signed-off-by: Guo Chao <guochao@...hong.com>
Signed-off-by: Yi Li <yili@...hong.com>
---
drivers/md/bcache/writeback.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 3c74996978da..186c4c6e1607 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -175,7 +175,15 @@ static void update_writeback_rate(struct work_struct *work)
struct cached_dev *dc = container_of(to_delayed_work(work),
struct cached_dev,
writeback_rate_update);
- struct cache_set *c = dc->disk.c;
+ struct cache_set *c = NULL;
+
+ mutex_lock(&bch_register_lock);
+ c = dc->disk.c;
+
+ if (c == NULL) {
+ mutex_unlock(&bch_register_lock);
+ return;
+ }
/*
* should check BCACHE_DEV_RATE_DW_RUNNING before calling
@@ -194,6 +202,7 @@ static void update_writeback_rate(struct work_struct *work)
clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
smp_mb__after_atomic();
+ mutex_unlock(&bch_register_lock);
return;
}
@@ -230,6 +239,7 @@ static void update_writeback_rate(struct work_struct *work)
clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
smp_mb__after_atomic();
+ mutex_unlock(&bch_register_lock);
}
static unsigned int writeback_delay(struct cached_dev *dc,
--
2.25.3
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