intel-iommu: possible circular locking dependency?
From: Jan Kiszka
Date: Mon Jul 24 2017 - 07:59:13 EST
Hi,
this trigger for this is out-of-tree [1], but my understanding so far is
that this is an in-tree issue:
[ 14.841871] ======================================================
[ 14.841874] WARNING: possible circular locking dependency detected
[ 14.841878] 4.13.0-rc2-dbg+ #174 Tainted: G O
[ 14.841881] ------------------------------------------------------
[ 14.841884] jailhouse/6120 is trying to acquire lock:
[ 14.841887] (dmar_global_lock){++++..}, at: [<ffffffff814d6e43>] dmar_pci_bus_notifier+0x4f/0xcb
[ 14.841907]
[ 14.841907] but task is already holding lock:
[ 14.841910] (&(&priv->bus_notifier)->rwsem){++++..}, at: [<ffffffff8106d853>] __blocking_notifier_call_chain+0x31/0x65
[ 14.841925]
[ 14.841925] which lock already depends on the new lock.
[ 14.841925]
[ 14.841930]
[ 14.841930] the existing dependency chain (in reverse order) is:
[ 14.841933]
[ 14.841933] -> #1 (&(&priv->bus_notifier)->rwsem){++++..}:
[ 14.841943] lock_acquire+0x148/0x1f6
[ 14.841951] down_write+0x3b/0x6a
[ 14.841954] blocking_notifier_chain_register+0x33/0x53
[ 14.841960] bus_register_notifier+0x1c/0x1e
[ 14.841972] dmar_dev_scope_init+0x2c6/0x2db
[ 14.841976] intel_iommu_init+0xeb/0x12cb
[ 14.841983] pci_iommu_init+0x17/0x41
[ 14.841989] do_one_initcall+0x90/0x143
[ 14.841994] kernel_init_freeable+0x1cc/0x256
[ 14.841999] kernel_init+0xe/0xf8
[ 14.842004] ret_from_fork+0x2a/0x40
[ 14.842008]
[ 14.842008] -> #0 (dmar_global_lock){++++..}:
[ 14.842017] __lock_acquire+0xfe4/0x1521
[ 14.842021] lock_acquire+0x148/0x1f6
[ 14.842026] down_write+0x3b/0x6a
[ 14.842031] dmar_pci_bus_notifier+0x4f/0xcb
[ 14.842036] notifier_call_chain+0x3c/0x5e
[ 14.842041] __blocking_notifier_call_chain+0x4c/0x65
[ 14.842046] blocking_notifier_call_chain+0x14/0x16
[ 14.842051] device_add+0x40c/0x522
[ 14.842062] pci_device_add+0x1c0/0x1ce
[ 14.842066] pci_scan_single_device+0x92/0x9d
[ 14.842071] pci_scan_slot+0x59/0xff
[ 14.842078] jailhouse_pci_do_all_devices+0x74/0x263 [jailhouse]
[ 14.842084] jailhouse_pci_virtual_root_devices_add+0x40/0x42 [jailhouse]
[ 14.842090] jailhouse_cmd_enable+0x4fd/0x5e3 [jailhouse]
[ 14.842096] jailhouse_ioctl+0x28/0x70 [jailhouse]
[ 14.842106] vfs_ioctl+0x18/0x34
[ 14.842111] do_vfs_ioctl+0x512/0x5da
[ 14.842116] SyS_ioctl+0x50/0x7b
[ 14.842121] entry_SYSCALL_64_fastpath+0x1f/0xbe
[ 14.842125]
[ 14.842125] other info that might help us debug this:
[ 14.842125]
[ 14.842134] Possible unsafe locking scenario:
[ 14.842134]
[ 14.842140] CPU0 CPU1
[ 14.842144] ---- ----
[ 14.842148] lock(&(&priv->bus_notifier)->rwsem);
[ 14.842155] lock(dmar_global_lock);
[ 14.842160] lock(&(&priv->bus_notifier)->rwsem);
[ 14.842166] lock(dmar_global_lock);
[ 14.842170]
[ 14.842170] *** DEADLOCK ***
[ 14.842170]
[ 14.842179] 2 locks held by jailhouse/6120:
[ 14.842183] #0: (jailhouse_lock){+.+.+.}, at: [<ffffffffa03c1fd3>] jailhouse_cmd_enable+0x130/0x5e3 [jailhouse]
[ 14.842194] #1: (&(&priv->bus_notifier)->rwsem){++++..}, at: [<ffffffff8106d853>] __blocking_notifier_call_chain+0x31/0x65
[ 14.842204]
[ 14.842204] stack backtrace:
[ 14.842211] CPU: 0 PID: 6120 Comm: jailhouse Tainted: G O 4.13.0-rc2-dbg+ #174
[ 14.842217] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.10.1-0-g8891697-prebuilt.qemu-project.org 04/01/2014
[ 14.842225] Call Trace:
[ 14.842232] dump_stack+0x85/0xbe
[ 14.842237] print_circular_bug+0x29b/0x2a9
[ 14.842243] __lock_acquire+0xfe4/0x1521
[ 14.842248] ? save_trace+0x3b/0x9b
[ 14.842253] lock_acquire+0x148/0x1f6
[ 14.842257] ? lock_acquire+0x148/0x1f6
[ 14.842262] ? dmar_pci_bus_notifier+0x4f/0xcb
[ 14.842268] down_write+0x3b/0x6a
[ 14.842272] ? dmar_pci_bus_notifier+0x4f/0xcb
[ 14.842277] dmar_pci_bus_notifier+0x4f/0xcb
[ 14.842282] notifier_call_chain+0x3c/0x5e
[ 14.842287] __blocking_notifier_call_chain+0x4c/0x65
[ 14.842292] blocking_notifier_call_chain+0x14/0x16
[ 14.842297] device_add+0x40c/0x522
[ 14.842302] pci_device_add+0x1c0/0x1ce
[ 14.842306] pci_scan_single_device+0x92/0x9d
[ 14.842311] pci_scan_slot+0x59/0xff
[ 14.842316] jailhouse_pci_do_all_devices+0x74/0x263 [jailhouse]
[ 14.842322] jailhouse_pci_virtual_root_devices_add+0x40/0x42 [jailhouse]
[ 14.842329] jailhouse_cmd_enable+0x4fd/0x5e3 [jailhouse]
[ 14.842337] jailhouse_ioctl+0x28/0x70 [jailhouse]
[ 14.842342] vfs_ioctl+0x18/0x34
[ 14.842346] do_vfs_ioctl+0x512/0x5da
[ 14.842352] ? kmem_cache_free+0x15b/0x1fa
[ 14.842357] ? entry_SYSCALL_64_fastpath+0x5/0xbe
[ 14.842362] ? trace_hardirqs_on_caller+0x180/0x19c
[ 14.842367] SyS_ioctl+0x50/0x7b
[ 14.842372] entry_SYSCALL_64_fastpath+0x1f/0xbe
Didn't see this with 4.12, so a 4.13 regression?
Jan
[1] https://github.com/siemens/jailhouse/blob/7ef4b98ebe04f49f63985b6547a09875dcbe28ec/driver/pci.c#L75--
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