From fb7a91746af18b2ebf596778b38a709cdbc488d3 Mon Sep 17 00:00:00 2001 From: Jack Morgenstein Date: Tue, 21 Mar 2017 12:57:06 +0200 Subject: [PATCH] IB/mlx4: Reduce SRIOV multicast cleanup warning message to debug level A warning message during SRIOV multicast cleanup should have actually been a debug level message. The condition generating the warning does no harm and can fill the message log. In some cases, during testing, some tests were so intense as to swamp the message log with these warning messages, causing a stall in the console message log output task. This stall caused an NMI to be sent to all CPUs (so that they all dumped their stacks into the message log). Aside from the message flood causing an NMI, the tests all passed. Once the message flood which caused the NMI is removed (by reducing the warning message to debug level), the NMI no longer occurs. Sample message log (console log) output illustrating the flood and resultant NMI (snippets with comments and modified with ... instead of hex digits, to satisfy checkpatch.pl): _mlx4_ib_mcg_port_cleanup: ... WARNING: group refcount 1!!!... *** About 4000 almost identical lines in less than one second *** _mlx4_ib_mcg_port_cleanup: ... WARNING: group refcount 1!!!... INFO: rcu_sched detected stalls on CPUs/tasks: { 17} (...) *** { 17} above indicates that CPU 17 was the one that stalled *** sending NMI to all CPUs: ... NMI backtrace for cpu 17 CPU: 17 PID: 45909 Comm: kworker/17:2 Hardware name: HP ProLiant DL360p Gen8, BIOS P71 09/08/2013 Workqueue: events fb_flashcursor task: ffff880478...... ti: ffff88064e...... task.ti: ffff88064e...... RIP: 0010:[ffffffff81......] [ffffffff81......] io_serial_in+0x15/0x20 RSP: 0018:ffff88064e257cb0 EFLAGS: 00000002 RAX: 0000000000...... RBX: ffffffff81...... RCX: 0000000000...... RDX: 0000000000...... RSI: 0000000000...... RDI: ffffffff81...... RBP: ffff88064e...... R08: ffffffff81...... R09: 0000000000...... R10: 0000000000...... R11: ffff88064e...... R12: 0000000000...... R13: 0000000000...... R14: ffffffff81...... R15: 0000000000...... FS: 0000000000......(0000) GS:ffff8804af......(0000) knlGS:000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080...... CR2: 00007f2a2f...... CR3: 0000000001...... CR4: 0000000000...... DR0: 0000000000...... DR1: 0000000000...... DR2: 0000000000...... DR3: 0000000000...... DR6: 00000000ff...... DR7: 0000000000...... Stack: ffff88064e...... ffffffff81...... ffffffff81...... 0000000000...... ffffffff81...... ffff88064e...... ffffffff81...... ffffffff81...... ffffffff81...... ffff88064e...... ffffffff81...... 0000000000...... Call Trace: [] wait_for_xmitr+0x3b/0xa0 [] serial8250_console_putchar+0x1c/0x30 [] ? serial8250_console_write+0x140/0x140 [] uart_console_write+0x3a/0x80 [] serial8250_console_write+0xae/0x140 [] call_console_drivers.constprop.15+0x91/0xf0 [] console_unlock+0x3bf/0x400 [] fb_flashcursor+0x5d/0x140 [] ? bit_clear+0x120/0x120 [] process_one_work+0x17b/0x470 [] worker_thread+0x11b/0x400 [] ? rescuer_thread+0x400/0x400 [] kthread+0xcf/0xe0 [] ? kthread_create_on_node+0x140/0x140 [] ret_from_fork+0x58/0x90 [] ? kthread_create_on_node+0x140/0x140 Code: 48 89 e5 d3 e6 48 63 f6 48 03 77 10 8b 06 5d c3 66 0f 1f 44 00 00 66 66 66 6 As indicated in the stack trace above, the console output task got swamped. Fixes: b9c5d6a64358 ("IB/mlx4: Add multicast group (MCG) paravirtualization for SR-IOV") Cc: # v3.6+ Signed-off-by: Jack Morgenstein Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- drivers/infiniband/hw/mlx4/mcg.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mlx4/mcg.c b/drivers/infiniband/hw/mlx4/mcg.c index e010fe459e67..8772d88d324d 100644 --- a/drivers/infiniband/hw/mlx4/mcg.c +++ b/drivers/infiniband/hw/mlx4/mcg.c @@ -1102,7 +1102,8 @@ static void _mlx4_ib_mcg_port_cleanup(struct mlx4_ib_demux_ctx *ctx, int destroy while ((p = rb_first(&ctx->mcg_table)) != NULL) { group = rb_entry(p, struct mcast_group, node); if (atomic_read(&group->refcount)) - mcg_warn_group(group, "group refcount %d!!! (pointer %p)\n", atomic_read(&group->refcount), group); + mcg_debug_group(group, "group refcount %d!!! (pointer %p)\n", + atomic_read(&group->refcount), group); force_clean_group(group); } -- 2.20.1