From: Íñigo Huguet ihuguet@redhat.com
[ Upstream commit ada74c5539eba06cf8b47d068f92e0b3963a9a6e ]
When creating VFs a kernel panic can happen when calling to efx_ef10_try_update_nic_stats_vf.
When releasing a DMA coherent buffer, sometimes, I don't know in what specific circumstances, it has to unmap memory with vunmap. It is disallowed to do that in IRQ context or with BH disabled. Otherwise, we hit this line in vunmap, causing the crash: BUG_ON(in_interrupt());
This patch reenables BH to release the buffer.
Log messages when the bug is hit: kernel BUG at mm/vmalloc.c:2727! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI CPU: 6 PID: 1462 Comm: NetworkManager Kdump: loaded Tainted: G I --------- --- 5.14.0-119.el9.x86_64 #1 Hardware name: Dell Inc. PowerEdge R740/06WXJT, BIOS 2.8.2 08/27/2020 RIP: 0010:vunmap+0x2e/0x30 ...skip... Call Trace: __iommu_dma_free+0x96/0x100 efx_nic_free_buffer+0x2b/0x40 [sfc] efx_ef10_try_update_nic_stats_vf+0x14a/0x1c0 [sfc] efx_ef10_update_stats_vf+0x18/0x40 [sfc] efx_start_all+0x15e/0x1d0 [sfc] efx_net_open+0x5a/0xe0 [sfc] __dev_open+0xe7/0x1a0 __dev_change_flags+0x1d7/0x240 dev_change_flags+0x21/0x60 ...skip...
Fixes: d778819609a2 ("sfc: DMA the VF stats only when requested") Reported-by: Ma Yuying yuma@redhat.com Signed-off-by: Íñigo Huguet ihuguet@redhat.com Acked-by: Edward Cree ecree.xilinx@gmail.com Link: https://lore.kernel.org/r/20220713092116.21238-1-ihuguet@redhat.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/sfc/ef10.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c index 4f0da3963b01..1dfb14a035f9 100644 --- a/drivers/net/ethernet/sfc/ef10.c +++ b/drivers/net/ethernet/sfc/ef10.c @@ -1896,7 +1896,10 @@ static int efx_ef10_try_update_nic_stats_vf(struct efx_nic *efx)
efx_update_sw_stats(efx, stats); out: + /* releasing a DMA coherent buffer with BH disabled can panic */ + spin_unlock_bh(&efx->stats_lock); efx_nic_free_buffer(efx, &stats_buf); + spin_lock_bh(&efx->stats_lock); return rc; }