6.18-stable review patch. If anyone has any objections, please let me know.
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From: Gerd Bayer gbayer@linux.ibm.com
[ Upstream commit 6a107cfe9c99a079e578a4c5eb70038101a3599f ]
Clear hca_devcom_comp in device's private data after unregistering it in LAG teardown. Otherwise a slightly lagging second pass through mlx5_unload_one() might try to unregister it again and trip over use-after-free.
On s390 almost all PCI level recovery events trigger two passes through mxl5_unload_one() - one through the poll_health() method and one through mlx5_pci_err_detected() as callback from generic PCI error recovery. While testing PCI error recovery paths with more kernel debug features enabled, this issue reproducibly led to kernel panics with the following call chain:
Unable to handle kernel pointer dereference in virtual kernel address space Failing address: 6b6b6b6b6b6b6000 TEID: 6b6b6b6b6b6b6803 ESOP-2 FSI Fault in home space mode while using kernel ASCE. AS:00000000705c4007 R3:0000000000000024 Oops: 0038 ilc:3 [#1]SMP
CPU: 14 UID: 0 PID: 156 Comm: kmcheck Kdump: loaded Not tainted 6.18.0-20251130.rc7.git0.16131a59cab1.300.fc43.s390x+debug #1 PREEMPT
Krnl PSW : 0404e00180000000 0000020fc86aa1dc (__lock_acquire+0x5c/0x15f0) R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 0000000000000000 0000020f00000001 6b6b6b6b6b6b6c33 0000000000000000 0000000000000000 0000000000000000 0000000000000001 0000000000000000 0000000000000000 0000020fca28b820 0000000000000000 0000010a1ced8100 0000010a1ced8100 0000020fc9775068 0000018fce14f8b8 0000018fce14f7f8 Krnl Code: 0000020fc86aa1cc: e3b003400004 lg %r11,832 0000020fc86aa1d2: a7840211 brc 8,0000020fc86aa5f4 *0000020fc86aa1d6: c09000df0b25 larl %r9,0000020fca28b820 >0000020fc86aa1dc: d50790002000 clc 0(8,%r9),0(%r2) 0000020fc86aa1e2: a7840209 brc 8,0000020fc86aa5f4 0000020fc86aa1e6: c0e001100401 larl %r14,0000020fca8aa9e8 0000020fc86aa1ec: c01000e25a00 larl %r1,0000020fca2f55ec 0000020fc86aa1f2: a7eb00e8 aghi %r14,232
Call Trace: __lock_acquire+0x5c/0x15f0 lock_acquire.part.0+0xf8/0x270 lock_acquire+0xb0/0x1b0 down_write+0x5a/0x250 mlx5_detach_device+0x42/0x110 [mlx5_core] mlx5_unload_one_devl_locked+0x50/0xc0 [mlx5_core] mlx5_unload_one+0x42/0x60 [mlx5_core] mlx5_pci_err_detected+0x94/0x150 [mlx5_core] zpci_event_attempt_error_recovery+0xcc/0x388
Fixes: 5a977b5833b7 ("net/mlx5: Lag, move devcom registration to LAG layer") Signed-off-by: Gerd Bayer gbayer@linux.ibm.com Reviewed-by: Moshe Shemesh moshe@nvidia.com Acked-by: Tariq Toukan tariqt@nvidia.com Link: https://patch.msgid.link/20251202-fix_lag-v1-1-59e8177ffce0@linux.ibm.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c index 3db0387bf6dcb..8ec04a5f434dd 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lag/lag.c @@ -1413,6 +1413,7 @@ static int __mlx5_lag_dev_add_mdev(struct mlx5_core_dev *dev) static void mlx5_lag_unregister_hca_devcom_comp(struct mlx5_core_dev *dev) { mlx5_devcom_unregister_component(dev->priv.hca_devcom_comp); + dev->priv.hca_devcom_comp = NULL; }
static int mlx5_lag_register_hca_devcom_comp(struct mlx5_core_dev *dev)