drbd: narrow rcu_read_lock in drbd_sync_handshake (d29e89e3) · Commits · 戴 / test

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>

drivers/block/drbd/drbd_receiver.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -3364,7 +3364,7 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device,
		enum drbd_conns rv = C_MASK;
		enum drbd_disk_state mydisk;
		struct net_conf *nc;
		int hg, rule_nr, rr_conflict, tentative;
		int hg, rule_nr, rr_conflict, tentative, always_asbp;

		mydisk = device->state.disk;
		if (mydisk == D_NEGOTIATING)
		@@ -3415,8 +3415,12 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device,

		rcu_read_lock();
		nc = rcu_dereference(peer_device->connection->net_conf);
		always_asbp = nc->always_asbp;
		rr_conflict = nc->rr_conflict;
		tentative = nc->tentative;
		rcu_read_unlock();

		if (hg == 100 \|\| (hg == -100 && nc->always_asbp)) {
		if (hg == 100 \|\| (hg == -100 && always_asbp)) {
		int pcount = (device->state.role == R_PRIMARY)
		+ (peer_role == R_PRIMARY);
		int forced = (hg == -100);
		@@ -3455,9 +3459,6 @@ static enum drbd_conns drbd_sync_handshake(struct drbd_peer_device *peer_device,
		"Sync from %s node\n",
		(hg < 0) ? "peer" : "this");
		}
		rr_conflict = nc->rr_conflict;
		tentative = nc->tentative;
		rcu_read_unlock();

		if (hg == -100) {
		/* FIXME this log message is not correct if we end up here

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