bisecting fixing commit since aea8526edf59da3ff5306ca408e13d8f6ab89b34
building syzkaller on 7bb222f7bcce6f16c2e110f4c3270e009aaf55e7
testing commit aea8526edf59da3ff5306ca408e13d8f6ab89b34 with gcc (GCC) 8.1.0
kernel signature: ac7bdbd7caeb3ef8ec63cbf1a8aa551cbf6e2a67ef5a9846f51116f4ef0ba739
all runs: crashed: WARNING in arch_install_hw_breakpoint
testing current HEAD 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14
testing commit 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14 with gcc (GCC) 8.1.0
kernel signature: 07e486063fd4f736e9b59cd2a657d17a925c4fe1f471d666aa5a94f5bc0d0aa1
run #0: crashed: WARNING in arch_install_hw_breakpoint
run #1: crashed: WARNING in arch_install_hw_breakpoint
run #2: crashed: WARNING in arch_install_hw_breakpoint
run #3: crashed: WARNING in arch_install_hw_breakpoint
run #4: crashed: WARNING in arch_install_hw_breakpoint
run #5: crashed: WARNING in arch_install_hw_breakpoint
run #6: crashed: WARNING in arch_install_hw_breakpoint
run #7: crashed: WARNING in arch_install_hw_breakpoint
run #8: crashed: WARNING in arch_install_hw_breakpoint
run #9: OK
revisions tested: 2, total time: 36m31.829152911s (build: 18m0.744940568s, test: 17m32.269070264s)
the crash still happens on HEAD
commit msg: Linux 4.14.173
crash: WARNING in arch_install_hw_breakpoint
Can't find any breakpoint slot
------------[ cut here ]------------
WARNING: CPU: 0 PID: 27060 at arch/x86/kernel/hw_breakpoint.c:121 arch_install_hw_breakpoint.cold.3+0x13/0x1a arch/x86/kernel/hw_breakpoint.c:121
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 27060 Comm: syz-executor.4 Not tainted 4.14.173-syzkaller #0
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+0xf7/0x13b lib/dump_stack.c:58
 panic+0x1b0/0x358 kernel/panic.c:183
 __warn.cold.8+0x25/0x2c kernel/panic.c:547
 report_bug+0x1a4/0x1f3 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 do_error_trap+0x1bd/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:963
RIP: 0010:arch_install_hw_breakpoint.cold.3+0x13/0x1a arch/x86/kernel/hw_breakpoint.c:121
RSP: 0018:ffff8881ff29f7f8 EFLAGS: 00010082
RAX: 000000000000001e RBX: 00000000fffffff0 RCX: 0000000000000000
RDX: 000000000000001e RSI: 0000000000000001 RDI: ffffed103fe53ef6
RBP: ffff8881ff29f838 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff8684fb86 R11: dffffc0000000000 R12: dffffc0000000000
R13: 0000000000000004 R14: 000000000001ecf8 R15: 000000000001ed00
 hw_breakpoint_add+0x75/0x100 kernel/events/hw_breakpoint.c:574
 event_sched_in.isra.107+0x3a1/0xb00 kernel/events/core.c:2128
 group_sched_in+0x101/0x450 kernel/events/core.c:2168
 ctx_flexible_sched_in kernel/events/core.c:3193 [inline]
 ctx_sched_in+0x84d/0x17b0 kernel/events/core.c:3239
 perf_event_sched_in+0x60/0x80 kernel/events/core.c:2326
 perf_event_context_sched_in kernel/events/core.c:3279 [inline]
 __perf_event_task_sched_in+0x4bc/0x7c0 kernel/events/core.c:3318
 perf_event_task_sched_in include/linux/perf_event.h:1087 [inline]
 finish_task_switch+0x1c2/0x650 kernel/sched/core.c:2664
 context_switch kernel/sched/core.c:2811 [inline]
 __schedule+0x788/0x1d20 kernel/sched/core.c:3384
 schedule+0x7f/0x1b0 kernel/sched/core.c:3428
 freezable_schedule include/linux/freezer.h:172 [inline]
 ptrace_stop+0x3a9/0x860 kernel/signal.c:1951
 do_jobctl_trap kernel/signal.c:2170 [inline]
 get_signal+0xbf5/0x1b30 kernel/signal.c:2297
 do_signal+0x7f/0x19a0 arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x114/0x1b0 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+0x416/0x5b0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459819
RSP: 002b:00007fb4bcfc5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000129
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000459819
RDX: 0000000000000016 RSI: 0000000000000a6e RDI: 0000000000000a6e
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000100 R11: 0000000000000246 R12: 00007fb4bcfc66d4
R13: 00000000004c6cd6 R14: 00000000004dbf68 R15: 00000000ffffffff

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