Greetings, 0day kernel testing robot got the below dmesg and the first bad commit is https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git master commit d57108d4f6791291e89d980e7f7a3566c32ab188 Author: Thomas Gleixner AuthorDate: Tue Sep 12 21:37:11 2017 +0200 Commit: Ingo Molnar CommitDate: Thu Sep 14 11:41:06 2017 +0200 watchdog/core: Get rid of the thread teardown/setup dance The lockup detector reconfiguration tears down all watchdog threads when the watchdog is disabled and sets them up again when its enabled. That's a pointless exercise. The watchdog threads are not consuming an insane amount of resources, so it's enough to set them up at init time and keep them in parked position when the watchdog is disabled and unpark them when it is reenabled. The smpboot thread infrastructure takes care of keeping the force parked threads in place even across cpu hotplug. Aside of that the code implements the park/unpark facility of smp hotplug threads on its own, which is even more pointless. We have functionality in the smpboot thread code to do so. Use the new thread management functions and get rid of the unholy mess. Signed-off-by: Thomas Gleixner Reviewed-by: Don Zickus Cc: Andrew Morton Cc: Borislav Petkov Cc: Chris Metcalf Cc: Linus Torvalds Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Sebastian Siewior Cc: Ulrich Obergfell Link: http://lkml.kernel.org/r/20170912194147.470370113@linutronix.de Signed-off-by: Ingo Molnar 2eb2527f84 watchdog/core: Create new thread handling infrastructure d57108d4f6 watchdog/core: Get rid of the thread teardown/setup dance 57f9efe285 Merge branch 'WIP.x86/fpu' +------------------------------------------+------------+------------+------------+ | | 2eb2527f84 | d57108d4f6 | 57f9efe285 | +------------------------------------------+------------+------------+------------+ | boot_successes | 35 | 0 | 0 | | boot_failures | 0 | 15 | 9 | | BUG:unable_to_handle_kernel | 0 | 15 | 9 | | Oops:#[##] | 0 | 15 | 9 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 15 | 9 | +------------------------------------------+------------+------------+------------+ [ 0.030029] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes) [ 0.033296] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0 [ 0.034018] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0, 1GB 0 [ 0.035023] CPU: Intel Common KVM processor (family: 0xf, model: 0x6, stepping: 0x1) [ 0.042302] Performance Events: unsupported Netburst CPU model 6 no PMU driver, software events only. [ 0.051650] BUG: unable to handle kernel NULL pointer dereference at 0000000000000208 [ 0.052000] IP: perf_event_release_kernel+0x14/0x1ed [ 0.052000] PGD 0 P4D 0 [ 0.052000] Oops: 0000 [#1] [ 0.052000] CPU: 0 PID: 1 Comm: swapper Not tainted 4.13.0-11828-gd57108d #1 [ 0.052000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014 [ 0.052000] task: ffff88001e532000 task.stack: ffffc90000008000 [ 0.052000] RIP: 0010:perf_event_release_kernel+0x14/0x1ed [ 0.052000] RSP: 0000:ffffc9000000be38 EFLAGS: 00010292 [ 0.052000] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 000000000313fa45 [ 0.052000] RDX: 0000000000000001 RSI: ffffffff828265e0 RDI: 0000000000000000 [ 0.052000] RBP: ffffc9000000beb8 R08: ffffc9000000bdc8 R09: 0000000000000000 [ 0.052000] R10: ffff88001e532000 R11: ffffc9000000bd68 R12: 0000000000000000 [ 0.052000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.052000] FS: 0000000000000000(0000) GS:ffffffff8262f000(0000) knlGS:0000000000000000 [ 0.052000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.052000] CR2: 0000000000000208 CR3: 0000000002618000 CR4: 00000000000006b0 [ 0.052000] Call Trace: [ 0.052000] ? trace_hardirqs_on_caller+0x162/0x198 [ 0.052000] hardlockup_detector_perf_cleanup+0x20/0x2d [ 0.052000] __lockup_detector_cleanup+0x2c/0x2e [ 0.052000] softlockup_update_smpboot_threads+0x48/0x4a [ 0.052000] softlockup_reconfigure_threads+0x21/0x5a [ 0.052000] lockup_detector_init+0x75/0x83 [ 0.052000] kernel_init_freeable+0x67/0xf0 [ 0.052000] ? rest_init+0x13a/0x13a [ 0.052000] kernel_init+0xe/0xf8 [ 0.052000] ret_from_fork+0x2a/0x40 [ 0.052000] Code: df e8 0c b2 ff ff 4c 89 e7 e8 89 13 bd 00 41 5b 5b 41 5c 41 5d c9 c3 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 89 fb 48 83 ec 58 <48> 83 bf 08 02 00 00 00 75 14 f6 87 8c 00 00 00 03 0f 84 9b 01 [ 0.052000] RIP: perf_event_release_kernel+0x14/0x1ed RSP: ffffc9000000be38 [ 0.052000] CR2: 0000000000000208 [ 0.052000] ---[ end trace ed0d2c92e47d08db ]--- [ 0.052000] Kernel panic - not syncing: Fatal exception # HH:MM RESULT GOOD BAD GOOD_BUT_DIRTY DIRTY_NOT_BAD git bisect start f2e99ca8b77c273bbdfdb8fde244eac3c906ac85 569dbb88e80deb68974ef6fdd6a13edb9d686261 -- git bisect good 05fbbb5abe5b8960120ec537339cdc4d670ed86b # 23:51 G 11 0 0 0 Merge 'rockchip/v4.14-armsoc/fixes64' into devel-catchup-201709141913 git bisect good 769ab76856cc29ad3c700b038689d39ef07de0cc # 00:42 G 11 0 0 0 Merge 'ipsec/master' into devel-catchup-201709141913 git bisect bad 209a6f71dbcae51351811b4ea0712b2705e64b68 # 01:06 B 0 3 15 0 Merge 'tip/master' into devel-catchup-201709141913 git bisect good 7f4be2d15edbc94fda928a05cdb2692cf6ce1109 # 03:08 G 11 0 0 0 Merge branch 'WIP.x86/fpu' git bisect good 2eb2527f847d1bd8d8fb9db1e8139db5d6eddb36 # 03:34 G 10 0 0 0 watchdog/core: Create new thread handling infrastructure git bisect bad 178b9f7a36d2c74a38274b66dd89f53611298a19 # 03:45 B 0 2 14 0 watchdog/hardlockup/perf: Implement init time perf validation git bisect bad 51d4052b01ca555e0d1d5fe297b309beb6c64aa0 # 03:59 B 0 5 17 0 watchdog/sysctl: Get rid of the #ifdeffery git bisect bad e8b62b2dd14f8f2427856ba24cb7db922bda9bfd # 04:29 B 0 5 19 2 watchdog/core: Further simplify sysctl handling git bisect bad d57108d4f6791291e89d980e7f7a3566c32ab188 # 04:45 B 0 2 15 1 watchdog/core: Get rid of the thread teardown/setup dance # first bad commit: [d57108d4f6791291e89d980e7f7a3566c32ab188] watchdog/core: Get rid of the thread teardown/setup dance git bisect good 2eb2527f847d1bd8d8fb9db1e8139db5d6eddb36 # 05:06 G 30 0 0 0 watchdog/core: Create new thread handling infrastructure # extra tests with CONFIG_DEBUG_INFO_REDUCED git bisect bad d57108d4f6791291e89d980e7f7a3566c32ab188 # 05:19 B 0 4 18 2 watchdog/core: Get rid of the thread teardown/setup dance # extra tests on HEAD of linux-devel/devel-catchup-201709141913 git bisect bad f2e99ca8b77c273bbdfdb8fde244eac3c906ac85 # 05:24 B 0 31 46 0 0day head guard for 'devel-catchup-201709141913' # extra tests on tree/branch tip/master git bisect bad 57f9efe2850368ea37ef1ed430dd948d0d143afe # 05:39 B 0 5 19 2 Merge branch 'WIP.x86/fpu' --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/lkp Intel Corporation