This is a note to let you know that I've just added the patch titled IB/cm: Fix a recently introduced deadlock to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ib-cm-fix-a-recently-introduced-deadlock.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 4bfdf635c668869c69fd18ece37ec66fb6f38fcf Mon Sep 17 00:00:00 2001 From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> Date: Fri, 1 Jan 2016 13:17:46 +0100 Subject: IB/cm: Fix a recently introduced deadlock From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> commit 4bfdf635c668869c69fd18ece37ec66fb6f38fcf upstream. ib_send_cm_drep() calls cm_enter_timewait() while holding a spinlock that can be locked from inside an interrupt handler. Hence do not enable interrupts inside cm_enter_timewait() if called with interrupts disabled. This patch fixes e.g. the following deadlock: Acked-by: Erez Shitrit <erezsh@xxxxxxxxxxxx> ================================= [ INFO: inconsistent lock state ] 4.4.0-rc7+ #1 Tainted: G E --------------------------------- inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. swapper/8/0 [HC1[1]:SC0[0]:HE0:SE1] takes: (&(&cm_id_priv->lock)->rlock){?.+...}, at: [<ffffffffa036eec4>] cm_establish+0x 74/0x1b0 [ib_cm] {HARDIRQ-ON-W} state was registered at: [<ffffffff810a3c11>] mark_held_locks+0x71/0x90 [<ffffffff810a3e87>] trace_hardirqs_on_caller+0xa7/0x1c0 [<ffffffff810a3fad>] trace_hardirqs_on+0xd/0x10 [<ffffffff8151c40b>] _raw_spin_unlock_irq+0x2b/0x40 [<ffffffffa036ea8e>] cm_enter_timewait+0xae/0x100 [ib_cm] [<ffffffffa036ff76>] ib_send_cm_drep+0xb6/0x190 [ib_cm] [<ffffffffa052ed08>] srp_cm_handler+0x128/0x1a0 [ib_srp] [<ffffffffa0370340>] cm_process_work+0x20/0xf0 [ib_cm] [<ffffffffa0371335>] cm_dreq_handler+0x135/0x2c0 [ib_cm] [<ffffffffa03733c5>] cm_work_handler+0x75/0xd0 [ib_cm] [<ffffffff8107184d>] process_one_work+0x1bd/0x460 [<ffffffff81073148>] worker_thread+0x118/0x420 [<ffffffff81078454>] kthread+0xe4/0x100 [<ffffffff8151cbbf>] ret_from_fork+0x3f/0x70 irq event stamp: 1672286 hardirqs last enabled at (1672283): [<ffffffff81408ec0>] poll_idle+0x10/0x80 hardirqs last disabled at (1672284): [<ffffffff8151d304>] common_interrupt+0x84/0x89 softirqs last enabled at (1672286): [<ffffffff8105b4dc>] _local_bh_enable+0x1c/0x50 softirqs last disabled at (1672285): [<ffffffff8105b697>] irq_enter+0x47/0x70 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&cm_id_priv->lock)->rlock); <Interrupt> lock(&(&cm_id_priv->lock)->rlock); *** DEADLOCK *** no locks held by swapper/8/0. stack backtrace: CPU: 8 PID: 0 Comm: swapper/8 Tainted: G E 4.4.0-rc7+ #1 Hardware name: Dell Inc. PowerEdge R430/03XKDV, BIOS 1.0.2 11/17/2014 ffff88045af5e950 ffff88046e503a88 ffffffff81251c1b 0000000000000007 0000000000000006 0000000000000003 ffff88045af5ddc0 ffff88046e503ad8 ffffffff810a32f4 0000000000000000 0000000000000000 0000000000000001 Call Trace: <IRQ> [<ffffffff81251c1b>] dump_stack+0x4f/0x74 [<ffffffff810a32f4>] print_usage_bug+0x184/0x190 [<ffffffff810a36e2>] mark_lock_irq+0xf2/0x290 [<ffffffff810a3995>] mark_lock+0x115/0x1b0 [<ffffffff810a3b8c>] mark_irqflags+0x15c/0x170 [<ffffffff810a4fef>] __lock_acquire+0x1ef/0x560 [<ffffffff810a53c2>] lock_acquire+0x62/0x80 [<ffffffff8151bd33>] _raw_spin_lock_irqsave+0x43/0x60 [<ffffffffa036eec4>] cm_establish+0x74/0x1b0 [ib_cm] [<ffffffffa036f031>] ib_cm_notify+0x31/0x100 [ib_cm] [<ffffffffa0637f24>] srpt_qp_event+0x54/0xd0 [ib_srpt] [<ffffffffa0196052>] mlx4_ib_qp_event+0x72/0xc0 [mlx4_ib] [<ffffffffa00775b9>] mlx4_qp_event+0x69/0xd0 [mlx4_core] [<ffffffffa006000e>] mlx4_eq_int+0x51e/0xd50 [mlx4_core] [<ffffffffa006084f>] mlx4_msi_x_interrupt+0xf/0x20 [mlx4_core] [<ffffffff810b67b0>] handle_irq_event_percpu+0x40/0x110 [<ffffffff810b68bf>] handle_irq_event+0x3f/0x70 [<ffffffff810ba7f9>] handle_edge_irq+0x79/0x120 [<ffffffff81007f3d>] handle_irq+0x5d/0x130 [<ffffffff810071fd>] do_IRQ+0x6d/0x130 [<ffffffff8151d309>] common_interrupt+0x89/0x89 <EOI> [<ffffffff8140895f>] cpuidle_enter_state+0xcf/0x200 [<ffffffff81408aa2>] cpuidle_enter+0x12/0x20 [<ffffffff810990d6>] call_cpuidle+0x36/0x60 [<ffffffff81099163>] cpuidle_idle_call+0x63/0x110 [<ffffffff8109930a>] cpu_idle_loop+0xfa/0x130 [<ffffffff8109934e>] cpu_startup_entry+0xe/0x10 [<ffffffff8103c443>] start_secondary+0x83/0x90 Fixes: commit be4b499323bf ("IB/cm: Do not queue work to a device that's going away") Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> Cc: Erez Shitrit <erezsh@xxxxxxxxxxxx> Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/infiniband/core/cm.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -782,11 +782,11 @@ static void cm_enter_timewait(struct cm_ wait_time = cm_convert_to_ms(cm_id_priv->av.timeout); /* Check if the device started its remove_one */ - spin_lock_irq(&cm.lock); + spin_lock_irqsave(&cm.lock, flags); if (!cm_dev->going_down) queue_delayed_work(cm.wq, &cm_id_priv->timewait_info->work.work, msecs_to_jiffies(wait_time)); - spin_unlock_irq(&cm.lock); + spin_unlock_irqrestore(&cm.lock, flags); cm_id_priv->timewait_info = NULL; } Patches currently in stable-queue which might be from bart.vanassche@xxxxxxxxxxx are queue-4.4/ib-cm-fix-a-recently-introduced-deadlock.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html