WARNING in arch_install_hw

WARNING in arch_install_hw_breakpoint
Status: upstream: reported syz repro on 2019/07/19 00:15
Reported-by: syzbot+bf749e036a2ef83f7175@syzkaller.appspotmail.com
First crash: 384d, last: 54d

Fix bisection: the fix commit could be any of (bisect log):

aea8526edf59 Linux 4.14.133
56dfe6252c68 Linux 4.14.188

similar bugs (3):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
android-414	WARNING in arch_install_hw_breakpoint	syz		2	502d	481d	0/1	public: reported syz repro on 2019/04/13 00:01
upstream	WARNING in arch_install_hw_breakpoint	C	cause+fix	8	384d	501d	0/17	upstream: reported C repro on 2019/03/24 06:22
android-49	WARNING in arch_install_hw_breakpoint	syz		3	384d	480d	0/3	public: reported syz repro on 2019/04/14 09:28

Sample crash report:

Can't find any breakpoint slot
------------[ cut here ]------------
WARNING: CPU: 0 PID: 27774 at arch/x86/kernel/hw_breakpoint.c:121 arch_install_hw_breakpoint.cold+0x13/0x1f /arch/x86/kernel/hw_breakpoint.c:121
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 27774 Comm: syz-executor.5 Not tainted 4.14.133 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack /lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x19c /lib/dump_stack.c:53
 panic+0x1f2/0x426 /kernel/panic.c:182
 __warn.cold+0x2f/0x36 /kernel/panic.c:546
 report_bug+0x216/0x254 /lib/bug.c:186
 fixup_bug /arch/x86/kernel/traps.c:177 [inline]
 fixup_bug /arch/x86/kernel/traps.c:172 [inline]
 do_error_trap+0x1bb/0x310 /arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 /arch/x86/kernel/traps.c:314
 invalid_op+0x1b/0x40 /arch/x86/entry/entry_64.S:960
RIP: 0010:arch_install_hw_breakpoint.cold+0x13/0x1f /arch/x86/kernel/hw_breakpoint.c:121
RSP: 0018:ffff8881f3f9f818 EFLAGS: 00010082
RAX: 000000000000001e RBX: ffff8880aee1ecf8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffed103e7f3ef9
RBP: ffff8881f3f9f858 R08: 000000000000001e R09: 0000000000000000
R10: 0000000000000000 R11: ffff8880808ae180 R12: ffff88808a05d2c0
R13: dffffc0000000000 R14: 0000000000000004 R15: 000000000001ed00
 hw_breakpoint_add+0x90/0x120 /kernel/events/hw_breakpoint.c:574
 event_sched_in.isra.0+0x3c7/0xba0 /kernel/events/core.c:2128
 group_sched_in+0x110/0x450 /kernel/events/core.c:2168
 ctx_flexible_sched_in /kernel/events/core.c:3193 [inline]
 ctx_sched_in+0x909/0x1700 /kernel/events/core.c:3239
 perf_event_sched_in+0x6e/0xa0 /kernel/events/core.c:2326
 perf_event_context_sched_in /kernel/events/core.c:3279 [inline]
 __perf_event_task_sched_in+0x574/0x7c0 /kernel/events/core.c:3318
 perf_event_task_sched_in /./include/linux/perf_event.h:1087 [inline]
 finish_task_switch+0x3e7/0x650 /kernel/sched/core.c:2663
 context_switch /kernel/sched/core.c:2810 [inline]
 __schedule+0x7c0/0x1cd0 /kernel/sched/core.c:3383
 schedule+0x92/0x1c0 /kernel/sched/core.c:3427
 freezable_schedule /./include/linux/freezer.h:172 [inline]
 ptrace_stop+0x41a/0x950 /kernel/signal.c:1942
 do_jobctl_trap /kernel/signal.c:2161 [inline]
 get_signal+0x1401/0x1cd0 /kernel/signal.c:2288
 do_signal+0x86/0x19a0 /arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x15c/0x220 /arch/x86/entry/common.c:160
 prepare_exit_to_usermode /arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath /arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4bc/0x640 /arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459819
RSP: 002b:00007fadbba62c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000129
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000459819
RDX: 0000000000000016 RSI: 0000000000000b17 RDI: 0000000000000b17
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000100 R11: 0000000000000246 R12: 00007fadbba636d4
R13: 00000000004c6cd6 R14: 00000000004dbf68 R15: 00000000ffffffff

======================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci2-linux-4-14	2019/07/18 23:14	linux-4.14.y	aea8526e	7bb222f7	.config	log	report	syz		hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@redhat.com, natechancellor@gmail.com, ndesaulniers@google.com, sashal@kernel.org, tglx@linutronix.de, x86@kernel.org