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| author | Jack Wang <jinpu.wang@cloud.ionos.com> | 2021-01-08 15:36:34 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-01-08 08:19:18 -0700 |
| commit | 3a21777c6ee99749bac10727b3c17e5bcfebe5c1 (patch) | |
| tree | 1e52f27631ca1b27410357c8047e33fdb6b98bd4 | |
| parent | ef8048dd2345d070c41bc7df16763fd4d8fac296 (diff) | |
| download | lwn-3a21777c6ee99749bac10727b3c17e5bcfebe5c1.tar.gz lwn-3a21777c6ee99749bac10727b3c17e5bcfebe5c1.zip | |
block/rnbd-clt: avoid module unload race with close confirmation
We had kernel panic, it is caused by unload module and last
close confirmation.
call trace:
[1196029.743127] free_sess+0x15/0x50 [rtrs_client]
[1196029.743128] rtrs_clt_close+0x4c/0x70 [rtrs_client]
[1196029.743129] ? rnbd_clt_unmap_device+0x1b0/0x1b0 [rnbd_client]
[1196029.743130] close_rtrs+0x25/0x50 [rnbd_client]
[1196029.743131] rnbd_client_exit+0x93/0xb99 [rnbd_client]
[1196029.743132] __x64_sys_delete_module+0x190/0x260
And in the crashdump confirmation kworker is also running.
PID: 6943 TASK: ffff9e2ac8098000 CPU: 4 COMMAND: "kworker/4:2"
#0 [ffffb206cf337c30] __schedule at ffffffff9f93f891
#1 [ffffb206cf337cc8] schedule at ffffffff9f93fe98
#2 [ffffb206cf337cd0] schedule_timeout at ffffffff9f943938
#3 [ffffb206cf337d50] wait_for_completion at ffffffff9f9410a7
#4 [ffffb206cf337da0] __flush_work at ffffffff9f08ce0e
#5 [ffffb206cf337e20] rtrs_clt_close_conns at ffffffffc0d5f668 [rtrs_client]
#6 [ffffb206cf337e48] rtrs_clt_close at ffffffffc0d5f801 [rtrs_client]
#7 [ffffb206cf337e68] close_rtrs at ffffffffc0d26255 [rnbd_client]
#8 [ffffb206cf337e78] free_sess at ffffffffc0d262ad [rnbd_client]
#9 [ffffb206cf337e88] rnbd_clt_put_dev at ffffffffc0d266a7 [rnbd_client]
The problem is both code path try to close same session, which lead to
panic.
To fix it, just skip the sess if the refcount already drop to 0.
Fixes: f7a7a5c228d4 ("block/rnbd: client: main functionality")
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/block/rnbd/rnbd-clt.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/block/rnbd/rnbd-clt.c b/drivers/block/rnbd/rnbd-clt.c index 506e9094487f..45a470076652 100644 --- a/drivers/block/rnbd/rnbd-clt.c +++ b/drivers/block/rnbd/rnbd-clt.c @@ -1697,7 +1697,8 @@ static void rnbd_destroy_sessions(void) */ list_for_each_entry_safe(sess, sn, &sess_list, list) { - WARN_ON(!rnbd_clt_get_sess(sess)); + if (!rnbd_clt_get_sess(sess)) + continue; close_rtrs(sess); list_for_each_entry_safe(dev, tn, &sess->devs_list, list) { /* |