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authorJack Wang <jinpu.wang@cloud.ionos.com>2021-01-08 15:36:34 +0100
committerJens Axboe <axboe@kernel.dk>2021-01-08 08:19:18 -0700
commit3a21777c6ee99749bac10727b3c17e5bcfebe5c1 (patch)
tree1e52f27631ca1b27410357c8047e33fdb6b98bd4
parentef8048dd2345d070c41bc7df16763fd4d8fac296 (diff)
downloadlinux-stericsson-3a21777c6ee99749bac10727b3c17e5bcfebe5c1.tar.gz
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.c3
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) {
/*