drbd: narrow rcu_read_lock in drbd_sync_handshake
[ Upstream commit d29e89e34952a9ad02c77109c71a80043544296e ]
So far there was the possibility that we called
genlmsg_new(GFP_NOIO)/mutex_lock() while holding an rcu_read_lock().
This included cases like:
drbd_sync_handshake (acquire the RCU lock)
drbd_asb_recover_1p
drbd_khelper
drbd_bcast_event
genlmsg_new(GFP_NOIO) --> may sleep
drbd_sync_handshake (acquire the RCU lock)
drbd_asb_recover_1p
drbd_khelper
notify_helper
genlmsg_new(GFP_NOIO) --> may sleep
drbd_sync_handshake (acquire the RCU lock)
drbd_asb_recover_1p
drbd_khelper
notify_helper
mutex_lock --> may sleep
While using GFP_ATOMIC whould have been possible in the first two cases,
the real fix is to narrow the rcu_read_lock.
Reported-by: Jia-Ju Bai <baijiaju1990@163.com>
Reviewed-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Roland Kammerer <roland.kammerer@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
1 file changed