From: ZhaoLong Wang wangzhaolong1@huawei.com
[ 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@huawei.com Reviewed-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Sasha Levin sashal@kernel.org --- 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 28110cd4400b5..fd0e8f948c3da 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -576,7 +576,7 @@ 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. @@ -1110,7 +1110,7 @@ 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);