bcache: fixup multiple threads crash

commit 887554ab96588de2917b6c8c73e552da082e5368 upstream.

When multiple threads to check btree nodes in parallel, the main
thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag:

wait_event_interruptible(check_state->wait,
                         atomic_read(&check_state->started) == 0 ||
                         test_bit(CACHE_SET_IO_DISABLE, &c->flags));

However, the bch_btree_node_read and bch_btree_node_read_done
maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE
will be set. If the flag already set, the main thread return
error. At the same time, maybe some threads still running and
read NULL pointer, the kernel will crash.

This patch change the event wait condition, the main thread must
wait for all threads to stop.

Fixes: 8e7102273f597 ("bcache: make bch_btree_check() to be multithreaded")
Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 88c573eeb59823bd38ddb38d51b14099fec0f935..ad9f16689419d31bc614e2546d9d5f18a82e72e3 100644 (file)
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -2060,9 +2060,11 @@ int bch_btree_check(struct cache_set *c)
                }
        }
 
+       /*
+        * Must wait for all threads to stop.
+        */
        wait_event_interruptible(check_state->wait,
-                                atomic_read(&check_state->started) == 0 ||
-                                 test_bit(CACHE_SET_IO_DISABLE, &c->flags));
+                                atomic_read(&check_state->started) == 0);
 
        for (i = 0; i < check_state->total_threads; i++) {
                if (check_state->infos[i].result) {

diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index c7560f66dca88ad4c2f9582cdbc7b674ae44a9fb..68d3dd6b4f1190460a41feee8e9e46a495b4ce73 100644 (file)
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -998,9 +998,11 @@ void bch_sectors_dirty_init(struct bcache_device *d)
                }
        }
 
+       /*
+        * Must wait for all threads to stop.
+        */
        wait_event_interruptible(state->wait,
-                atomic_read(&state->started) == 0 ||
-                test_bit(CACHE_SET_IO_DISABLE, &c->flags));
+                atomic_read(&state->started) == 0);
 
 out:
        kfree(state);