From: ZhaoLong Wang <wangzhaolong1@xxxxxxxxxx>
[ Upstream commit f773f0a331d6c41733b17bebbc1b6cae12e016f5 ]
During the processing of the bgt, if the sync_erase() return -EBUSY
or some other error code in __erase_worker(),schedule_erase() called
again lead to the down_read(ubi->work_sem) hold twice and may get
block by down_write(ubi->work_sem) in ubi_update_fastmap(),
which cause deadlock.
ubi bgt other task
do_work
down_read(&ubi->work_sem) ubi_update_fastmap
erase_worker # Blocked by down_read
__erase_worker down_write(&ubi->work_sem)
schedule_erase
schedule_ubi_work
down_read(&ubi->work_sem)
Fix this by changing input parameter @nested of the schedule_erase() to
'true' to avoid recursively acquiring the down_read(&ubi->work_sem).
Also, fix the incorrect comment about @nested parameter of the
schedule_erase() because when down_write(ubi->work_sem) is held, the
@nested is also need be true.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217093
Fixes: 2e8f08deabbc ("ubi: Fix races around ubi_refill_pools()")
Signed-off-by: ZhaoLong Wang <wangzhaolong1@xxxxxxxxxx>
Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/mtd/ubi/wl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 2ee0e60c43c2e..4427018ad4d9b 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -575,7 +575,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
* @vol_id: the volume ID that last used this PEB
* @lnum: the last used logical eraseblock number for the PEB
* @torture: if the physical eraseblock has to be tortured
- * @nested: denotes whether the work_sem is already held in read mode
+ * @nested: denotes whether the work_sem is already held
*
* This function returns zero in case of success and a %-ENOMEM in case of
* failure.
@@ -1121,7 +1121,7 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
int err1;
/* Re-schedule the LEB for erasure */
- err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false);
+ err1 = schedule_erase(ubi, e, vol_id, lnum, 0, true);
if (err1) {
spin_lock(&ubi->wl_lock);
wl_entry_destroy(ubi, e);
--
2.39.2
