git bisect start
# bad: [0ecfebd2b52404ae0c54a878c872bb93363ada36] Linux 5.2
git bisect bad 0ecfebd2b52404ae0c54a878c872bb93363ada36
# good: [e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd] Linux 5.1
git bisect good e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd
# bad: [a2d635decbfa9c1e4ae15cb05b68b2559f7f827c] Merge tag 'drm-next-2019-05-09' of git://anongit.freedesktop.org/drm/drm
git bisect bad a2d635decbfa9c1e4ae15cb05b68b2559f7f827c
# bad: [82efe439599439a5e1e225ce5740e6cfb777a7dd] Merge tag 'devicetree-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
git bisect bad 82efe439599439a5e1e225ce5740e6cfb777a7dd
# bad: [78438ce18f26dbcaa8993bb45d20ffb0cec3bc3e] Merge branch 'stable-fodder' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
git bisect bad 78438ce18f26dbcaa8993bb45d20ffb0cec3bc3e
# bad: [275b103a26e218b3d739e5ab15be6b40303a1428] Merge tag 'edac_for_5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp
git bisect bad 275b103a26e218b3d739e5ab15be6b40303a1428
# bad: [0bc40e549aeea2de20fc571749de9bbfc099fb34] Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 0bc40e549aeea2de20fc571749de9bbfc099fb34
# good: [007dc78fea62610bf06829e38f1d8c69b6ea5af6] Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 007dc78fea62610bf06829e38f1d8c69b6ea5af6
# bad: [a0e928ed7c603a47dca8643e58db224a799ff2c5] Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad a0e928ed7c603a47dca8643e58db224a799ff2c5
# good: [f447e4eb3ad1e60d173ca997fcb2ef2a66f12574] perf/x86/intel: Force resched when TFA sysctl is modified
git bisect good f447e4eb3ad1e60d173ca997fcb2ef2a66f12574
# bad: [08ae95f4fd3b38b257f5dc7e6507e071c27ba0d5] nohz_full: Allow the boot CPU to be nohz_full
git bisect bad 08ae95f4fd3b38b257f5dc7e6507e071c27ba0d5
# bad: [bee9853932e90ce94bce4276ec6b7b06bc48070b] sched/core: Fix typo in comment
git bisect bad bee9853932e90ce94bce4276ec6b7b06bc48070b
# good: [d8743230c9f4e92f370ecd2a90c680ddcede6ae5] sched/topology: Fix build_sched_groups() comment
git bisect good d8743230c9f4e92f370ecd2a90c680ddcede6ae5
# bad: [6d25be5782e482eb93e3de0c94d0a517879377d0] sched/core, workqueues: Distangle worker accounting from rq lock
git bisect bad 6d25be5782e482eb93e3de0c94d0a517879377d0
# good: [e2abb398115e9c33f3d1e25bf6d1d08badc58b13] sched/fair: Remove unneeded prototype of capacity_of()
git bisect good e2abb398115e9c33f3d1e25bf6d1d08badc58b13
# first bad commit: [6d25be5782e482eb93e3de0c94d0a517879377d0] sched/core, workqueues: Distangle worker accounting from rq lock

In each bisection step I first ran `make oldconfig' using the 5.1.0
config and accepting the defaults of all new options, then built and
installed the kernel.  I tested by booting the kernel, then running
startx (openbox), emacs and firefox, exiting all of these and then
running `shutdown -h now' in the tty.  Here's a summary of the results:

1st test: power off 45 seconds after the message "Bringing down the loopback
 interface" (the last thing done in LFS by `shutdown' before it runs `halt -d
 -f -i -p'); I told git this is bad, though it was a shorter hang than most
 others I've experienced.
2nd test: power off 1'56" after loopback message (bad).
3rd test: power off 2'03" after loopback message (bad).
4th test: power off 1'47" after loopback message (bad).
5th test: waited more than 3 minutes after loopback message, no power
 off, pressed restart button (bad). 
6th test: power off within 4 seconds after loopback message (good). 
7th test: power off after 1'28" after loopback message (bad).
8th test: power off within 4 seconds after loopback message (good).
9th test: power off 2'50" after loopback message (bad).
10th test: power off 2'06" after loopback message (bad).
11th test: power off within 4 seconds after loopback message (good).
12th test: power off 2'23" after loopback message (bad).
13th test: power off within 4 seconds after loopback message (good).