Comment 5 for bug 1535307

I tested with linux-headers-4.4.0-040400 / linux-headers-4.4.0-040400-generic / linux-image-4.4.0-040400-generic 4.4.0-040400.201601101930. The kernel lockups did *not* reproduce.

Two caveats:

(1) I did get this kernel warning in the log:
Jan 21 18:00:08 e104462 kernel: [ 171.577000] ------------[ cut here ]------------
Jan 21 18:00:08 e104462 kernel: [ 171.577005] WARNING: CPU: 6 PID: 14136 at /home/kernel/COD/linux/kernel/signal.c:2072 get_signal+0x597/0x600()
Jan 21 18:00:08 e104462 kernel: [ 171.577006] Modules linked in: rfcomm bnep bluetooth nfsd auth_rpcgss nfs_acl nfs binfmt_misc lockd grace sunrpc fscache drbg ansi_cprng snd_hda_codec_hdmi intel_rapl x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm dm_crypt irqbypass crct10dif_pclmul crc32_pclmul aesni_intel aes_x86_64 lrw snd_hda_codec_realtek snd_hda_codec_generic gf128mul glue_helper ablk_helper snd_hda_intel cryptd snd_hda_codec snd_hda_core snd_hwdep input_leds pl2303 snd_pcm usbserial snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd 8250_fintek soundcore mei_me mei shpchp ie31200_edac lpc_ich ppdev edac_core serio_raw mac_hid parport_pc lp parport hid_generic usbhid hid uas usb_storage nouveau mxm_wmi i2c_algo_bit ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops e1000e drm ahci psmouse libahci ptp pps_core wmi fjes video
Jan 21 18:00:08 e104462 kernel: [ 171.577037] CPU: 6 PID: 14136 Comm: block-z8iSdZiRK Not tainted 4.4.0-040400-generic #201601101930
Jan 21 18:00:08 e104462 kernel: [ 171.577038] Hardware name: LENOVO 32281S1/MAHOBAY, BIOS 9SKT71AUS 07/02/2013
Jan 21 18:00:08 e104462 kernel: [ 171.577039] 0000000000000000 00000000a495bf0f ffff88040afdbd20 ffffffff813c8d94
Jan 21 18:00:08 e104462 kernel: [ 171.577040] 0000000000000000 ffff88040afdbd58 ffffffff8107dba2 0000000000000000
Jan 21 18:00:08 e104462 kernel: [ 171.577042] ffff88040afdbe38 0000000000008000 ffff88040afdbf58 ffff880405d58000
Jan 21 18:00:08 e104462 kernel: [ 171.577043] Call Trace:
Jan 21 18:00:08 e104462 kernel: [ 171.577046] [<ffffffff813c8d94>] dump_stack+0x44/0x60
Jan 21 18:00:08 e104462 kernel: [ 171.577049] [<ffffffff8107dba2>] warn_slowpath_common+0x82/0xc0
Jan 21 18:00:08 e104462 kernel: [ 171.577050] [<ffffffff8107dcea>] warn_slowpath_null+0x1a/0x20
Jan 21 18:00:08 e104462 kernel: [ 171.577051] [<ffffffff8108d0e7>] get_signal+0x597/0x600
Jan 21 18:00:08 e104462 kernel: [ 171.577053] [<ffffffff81016517>] do_signal+0x37/0x6f0
Jan 21 18:00:08 e104462 kernel: [ 171.577055] [<ffffffff817f9925>] ? schedule+0x35/0x80
Jan 21 18:00:08 e104462 kernel: [ 171.577057] [<ffffffff81080b96>] ? do_exit+0x736/0xab0
Jan 21 18:00:08 e104462 kernel: [ 171.577058] [<ffffffff81021272>] ? __switch_to_xtra+0xe2/0x1b0
Jan 21 18:00:08 e104462 kernel: [ 171.577061] [<ffffffff8100320c>] exit_to_usermode_loop+0x8c/0xd0
Jan 21 18:00:08 e104462 kernel: [ 171.577062] [<ffffffff81003c2e>] syscall_return_slowpath+0x4e/0x60
Jan 21 18:00:08 e104462 kernel: [ 171.577064] [<ffffffff817fdb18>] int_ret_from_sys_call+0x25/0x8f
Jan 21 18:00:08 e104462 kernel: [ 171.577065] ---[ end trace 1c1af43c0c2249f3 ]---

but it seems to be a completely different thing from the lockup back traces seen with the 3.13 kernel.

(2) rr complains:
1134: [FATAL /home/petmay01/src/rr/src/Monkeypatcher.cc:660:patch_after_exec_arch<rr::X86Arch>() errno: 0 'Success']
1134: -> Failed to monkeypatch vdso: your __kernel_vsyscall() wasn't recognized.
1134: Syscall buffering is now effectively disabled. If you're OK with
1134: running rr without syscallbuf, then run the recorder passing the
1134: --no-syscall-buffer arg.
1134: If you're *not* OK with that, file an issue.

which indicates that it's not happy with running under a 4.4 kernel in some way, and the code being run won't be the same as it was under the 3.13 kernel. (I filed https://github.com/mozilla/rr/issues/1627 against rr about that.)