Seems to be rather sporadic, but does happen occasionally on various tests on bsw-nuc-2. See http://benchsrv.fi.intel.com/archive/results/CI_IGT_test/igt@kms_pipe_crc_basic@suspend-read-crc-pipe-c.html Might be related to bug #93294, but that one is fixed. [ 424.350873] ====================================================== [ 424.350874] [ INFO: possible circular locking dependency detected ] [ 424.350878] 4.5.0-rc6-gfxbench+ #1 Tainted: G U [ 424.350879] ------------------------------------------------------- [ 424.350881] rtcwake/7413 is trying to acquire lock: [ 424.350895] (s_active#43){++++.+}, at: [<ffffffff8124ec70>] kernfs_remove_by_name_ns+0x40/0xa0 [ 424.350896] but task is already holding lock: [ 424.350903] (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81078c4d>] cpu_hotplug_begin+0x6d/0xc0 [ 424.350904] which lock already depends on the new lock. [ 424.350905] the existing dependency chain (in reverse order) is: [ 424.350908] -> #3 (cpu_hotplug.lock){+.+.+.}: [ 424.350913] [<ffffffff810cd09b>] lock_acquire+0xdb/0x1f0 [ 424.350918] [<ffffffff817be562>] mutex_lock_nested+0x62/0x3b0 [ 424.350920] [<ffffffff81078911>] get_online_cpus+0x61/0x80 [ 424.350924] [<ffffffff81117f1b>] stop_machine+0x1b/0xe0 [ 424.350929] [<ffffffffa016079d>] 0xffffffffa016079d [ 424.350931] [<ffffffffa0164d86>] 0xffffffffa0164d86 [ 424.350933] [<ffffffffa0166589>] 0xffffffffa0166589 [ 424.350935] [<ffffffffa016de47>] 0xffffffffa016de47 [ 424.350937] [<ffffffffa016e0d8>] 0xffffffffa016e0d8 [ 424.350939] [<ffffffffa0181d9e>] 0xffffffffa0181d9e [ 424.350942] [<ffffffffa017edc2>] 0xffffffffa017edc2 [ 424.350944] [<ffffffffa016eb73>] 0xffffffffa016eb73 [ 424.350946] [<ffffffffa01f2a21>] 0xffffffffa01f2a21 [ 424.350951] [<ffffffff81515ea4>] drm_dev_register+0xa4/0xb0 [ 424.350954] [<ffffffff815180ae>] drm_get_pci_dev+0xce/0x1e0 [ 424.350956] [<ffffffffa012e2ff>] 0xffffffffa012e2ff [ 424.350961] [<ffffffff814430f7>] pci_device_probe+0x87/0xf0 [ 424.350965] [<ffffffff81539999>] driver_probe_device+0x229/0x450 [ 424.350968] [<ffffffff81539c43>] __driver_attach+0x83/0x90 [ 424.350971] [<ffffffff81537671>] bus_for_each_dev+0x61/0xa0 [ 424.350974] [<ffffffff81539289>] driver_attach+0x19/0x20 [ 424.350977] [<ffffffff81538d6f>] bus_add_driver+0x1ef/0x290 [ 424.350980] [<ffffffff8153a90b>] driver_register+0x5b/0xe0 [ 424.350983] [<ffffffff8144202b>] __pci_register_driver+0x5b/0x60 [ 424.350986] [<ffffffff81518296>] drm_pci_init+0xd6/0x100 [ 424.350988] [<ffffffffa0265094>] 0xffffffffa0265094 [ 424.350993] [<ffffffff810003de>] do_one_initcall+0xae/0x1d0 [ 424.350996] [<ffffffff8115a5a5>] do_init_module+0x5b/0x1c6 [ 424.351000] [<ffffffff81106f80>] load_module+0x1c20/0x2490 [ 424.351003] [<ffffffff811079de>] SyS_finit_module+0x7e/0xa0 [ 424.351006] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 424.351010] -> #2 (&dev->struct_mutex){+.+.+.}: [ 424.351013] [<ffffffff810cd09b>] lock_acquire+0xdb/0x1f0 [ 424.351016] [<ffffffff815113e7>] drm_gem_mmap+0x1c7/0x270 [ 424.351020] [<ffffffff81197ec4>] mmap_region+0x334/0x580 [ 424.351023] [<ffffffff81198474>] do_mmap+0x364/0x410 [ 424.351027] [<ffffffff8117c65d>] vm_mmap_pgoff+0x6d/0xa0 [ 424.351030] [<ffffffff811965a4>] SyS_mmap_pgoff+0x184/0x220 [ 424.351033] [<ffffffff8100a1ed>] SyS_mmap+0x1d/0x20 [ 424.351037] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 424.351040] -> #1 (&mm->mmap_sem){++++++}: [ 424.351043] [<ffffffff810cd09b>] lock_acquire+0xdb/0x1f0 [ 424.351046] [<ffffffff8118d0e5>] __might_fault+0x75/0xa0 [ 424.351049] [<ffffffff8124f67a>] kernfs_fop_write+0x8a/0x180 [ 424.351052] [<ffffffff811d2653>] __vfs_write+0x23/0xe0 [ 424.351055] [<ffffffff811d33b4>] vfs_write+0xa4/0x190 [ 424.351058] [<ffffffff811d4254>] SyS_write+0x44/0xb0 [ 424.351061] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 424.351065] -> #0 (s_active#43){++++.+}: [ 424.351068] [<ffffffff810cc659>] __lock_acquire+0x1fc9/0x20f0 [ 424.351070] [<ffffffff810cd09b>] lock_acquire+0xdb/0x1f0 [ 424.351073] [<ffffffff8124dca0>] __kernfs_remove+0x210/0x2f0 [ 424.351076] [<ffffffff8124ec70>] kernfs_remove_by_name_ns+0x40/0xa0 [ 424.351079] [<ffffffff8125101d>] sysfs_unmerge_group+0x3d/0x60 [ 424.351083] [<ffffffff81541704>] dpm_sysfs_remove+0x34/0x60 [ 424.351086] [<ffffffff81535204>] device_del+0x44/0x250 [ 424.351088] [<ffffffff81535429>] device_unregister+0x19/0x60 [ 424.351091] [<ffffffff8153fac1>] cpu_cache_sysfs_exit+0x51/0xb0 [ 424.351094] [<ffffffff81540098>] cacheinfo_cpu_callback+0x38/0x70 [ 424.351098] [<ffffffff8109b499>] notifier_call_chain+0x39/0xa0 [ 424.351100] [<ffffffff8109b509>] __raw_notifier_call_chain+0x9/0x10 [ 424.351103] [<ffffffff81078b2e>] cpu_notify+0x1e/0x40 [ 424.351106] [<ffffffff81078bc9>] cpu_notify_nofail+0x9/0x20 [ 424.351109] [<ffffffff81078f13>] _cpu_down+0x233/0x340 [ 424.351112] [<ffffffff81079469>] disable_nonboot_cpus+0xc9/0x380 [ 424.351116] [<ffffffff810d36fe>] suspend_devices_and_enter+0x58e/0xbb0 [ 424.351118] [<ffffffff810d42ec>] pm_suspend+0x5cc/0x970 [ 424.351121] [<ffffffff810d2447>] state_store+0x77/0xe0 [ 424.351125] [<ffffffff813fdc1f>] kobj_attr_store+0xf/0x20 [ 424.351128] [<ffffffff81250370>] sysfs_kf_write+0x40/0x50 [ 424.351131] [<ffffffff8124f72c>] kernfs_fop_write+0x13c/0x180 [ 424.351133] [<ffffffff811d2653>] __vfs_write+0x23/0xe0 [ 424.351136] [<ffffffff811d33b4>] vfs_write+0xa4/0x190 [ 424.351139] [<ffffffff811d4254>] SyS_write+0x44/0xb0 [ 424.351142] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 424.351143] other info that might help us debug this: [ 424.351148] Chain exists of: s_active#43 --> &dev->struct_mutex --> cpu_hotplug.lock [ 424.351149] Possible unsafe locking scenario: [ 424.351150] CPU0 CPU1 [ 424.351151] ---- ---- [ 424.351153] lock(cpu_hotplug.lock); [ 424.351155] lock(&dev->struct_mutex); [ 424.351157] lock(cpu_hotplug.lock); [ 424.351159] lock(s_active#43); [ 424.351160] *** DEADLOCK *** [ 424.351162] 8 locks held by rtcwake/7413: [ 424.351168] #0: (sb_writers#6){.+.+.+}, at: [<ffffffff811d69e4>] __sb_start_write+0xd4/0xf0 [ 424.351174] #1: (&of->mutex){+.+.+.}, at: [<ffffffff8124f651>] kernfs_fop_write+0x61/0x180 [ 424.351180] #2: (s_active#227){.+.+.+}, at: [<ffffffff8124f659>] kernfs_fop_write+0x69/0x180 [ 424.351185] #3: (pm_mutex){+.+...}, at: [<ffffffff810d3fbe>] pm_suspend+0x29e/0x970 [ 424.351192] #4: (acpi_scan_lock){+.+.+.}, at: [<ffffffff814762fb>] acpi_scan_lock_acquire+0x12/0x14 [ 424.351198] #5: (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff810793c4>] disable_nonboot_cpus+0x24/0x380 [ 424.351203] #6: (cpu_hotplug.dep_map){++++++}, at: [<ffffffff81078be0>] cpu_hotplug_begin+0x0/0xc0 [ 424.351208] #7: (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81078c4d>] cpu_hotplug_begin+0x6d/0xc0 [ 424.351209] stack backtrace: [ 424.351212] CPU: 0 PID: 7413 Comm: rtcwake Tainted: G U 4.5.0-rc6-gfxbench+ #1 [ 424.351213] Hardware name: /NUC5CPYB, BIOS PYBSWCEL.86A.0040.2015.0814.1353 08/14/2015 [ 424.351219] 0000000000000000 ffff88003668b820 ffffffff813fba95 ffffffff825f5670 [ 424.351222] ffffffff825a1220 ffff88003668b860 ffffffff810c8cac ffff88003668b8c0 [ 424.351226] ffff88017b3c2ec0 ffff88017b3c2580 0000000000000008 ffff88017b3c2ee8 [ 424.351227] Call Trace: [ 424.351231] [<ffffffff813fba95>] dump_stack+0x67/0x92 [ 424.351233] [<ffffffff810c8cac>] print_circular_bug+0x1fc/0x310 [ 424.351235] [<ffffffff810cc659>] __lock_acquire+0x1fc9/0x20f0 [ 424.351238] [<ffffffff810cd09b>] lock_acquire+0xdb/0x1f0 [ 424.351241] [<ffffffff8124ec70>] ? kernfs_remove_by_name_ns+0x40/0xa0 [ 424.351243] [<ffffffff8124dca0>] __kernfs_remove+0x210/0x2f0 [ 424.351246] [<ffffffff8124ec70>] ? kernfs_remove_by_name_ns+0x40/0xa0 [ 424.351248] [<ffffffff8124deb8>] ? kernfs_find_ns+0x78/0x130 [ 424.351250] [<ffffffff8124ec70>] kernfs_remove_by_name_ns+0x40/0xa0 [ 424.351253] [<ffffffff8125101d>] sysfs_unmerge_group+0x3d/0x60 [ 424.351255] [<ffffffff81541704>] dpm_sysfs_remove+0x34/0x60 [ 424.351258] [<ffffffff81535204>] device_del+0x44/0x250 [ 424.351260] [<ffffffff81535429>] device_unregister+0x19/0x60 [ 424.351262] [<ffffffff8153fac1>] cpu_cache_sysfs_exit+0x51/0xb0 [ 424.351265] [<ffffffff81540098>] cacheinfo_cpu_callback+0x38/0x70 [ 424.351267] [<ffffffff8109b499>] notifier_call_chain+0x39/0xa0 [ 424.351270] [<ffffffff8109b509>] __raw_notifier_call_chain+0x9/0x10 [ 424.351272] [<ffffffff81078b2e>] cpu_notify+0x1e/0x40 [ 424.351274] [<ffffffff81078bc9>] cpu_notify_nofail+0x9/0x20 [ 424.351276] [<ffffffff81078f13>] _cpu_down+0x233/0x340 [ 424.351279] [<ffffffff810e4940>] ? __call_rcu.constprop.61+0x2f0/0x2f0 [ 424.351281] [<ffffffff810e49a0>] ? call_rcu_bh+0x20/0x20 [ 424.351285] [<ffffffff810e0430>] ? trace_raw_output_rcu_utilization+0x60/0x60 [ 424.351288] [<ffffffff810e0430>] ? trace_raw_output_rcu_utilization+0x60/0x60 [ 424.351291] [<ffffffff81079469>] disable_nonboot_cpus+0xc9/0x380 [ 424.351293] [<ffffffff810d36fe>] suspend_devices_and_enter+0x58e/0xbb0 [ 424.351296] [<ffffffff810c7939>] ? __lock_is_held+0x49/0x70 [ 424.351299] [<ffffffff810d42ec>] pm_suspend+0x5cc/0x970 [ 424.351301] [<ffffffff810d2447>] state_store+0x77/0xe0 [ 424.351304] [<ffffffff813fdc1f>] kobj_attr_store+0xf/0x20 [ 424.351306] [<ffffffff81250370>] sysfs_kf_write+0x40/0x50 [ 424.351309] [<ffffffff8124f72c>] kernfs_fop_write+0x13c/0x180 [ 424.351311] [<ffffffff811d2653>] __vfs_write+0x23/0xe0 [ 424.351314] [<ffffffff810c6332>] ? percpu_down_read+0x52/0x90 [ 424.351316] [<ffffffff811d69e4>] ? __sb_start_write+0xd4/0xf0 [ 424.351318] [<ffffffff811d69e4>] ? __sb_start_write+0xd4/0xf0 [ 424.351320] [<ffffffff811d33b4>] vfs_write+0xa4/0x190 [ 424.351324] [<ffffffff811f1b2a>] ? __fget_light+0x6a/0x90 [ 424.351326] [<ffffffff811d4254>] SyS_write+0x44/0xb0 [ 424.351329] [<ffffffff817c2e1b>] entry_SYSCALL_64_fastpath+0x16/0x73 [ 424.360008] cache: parent cpu1 should not be sleeping [ 425.501876] sd 0:0:0:0: [sda] Starting disk
*** This bug has been marked as a duplicate of bug 94350 ***
Note that CI *should* be catching another lockdep chain not involving kernfs. A real worry that they are not.
Closing as duplicate of closed+fixed.
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.