Re: [syzbot] [kernel?] KMSAN: uninit-value in __flush_smp_call_function_queue

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in __flush_smp_call_function_queue

=====================================================
BUG: KMSAN: uninit-value in __flush_smp_call_function_queue+0x362/0x18e0 kernel/smp.c:535
 __flush_smp_call_function_queue+0x362/0x18e0 kernel/smp.c:535
 generic_smp_call_function_single_interrupt+0x1c/0x30 kernel/smp.c:463
 __sysvec_call_function_single+0x4b/0x3e0 arch/x86/kernel/smp.c:271
 instr_sysvec_call_function_single arch/x86/kernel/smp.c:266 [inline]
 sysvec_call_function_single+0x7c/0x90 arch/x86/kernel/smp.c:266
 asm_sysvec_call_function_single+0x1f/0x30 arch/x86/include/asm/idtentry.h:704
 native_irq_enable arch/x86/include/asm/irqflags.h:42 [inline]
 arch_local_irq_enable arch/x86/include/asm/irqflags.h:119 [inline]
 raw_spin_rq_unlock_irq kernel/sched/sched.h:1629 [inline]
 finish_lock_switch kernel/sched/core.c:5032 [inline]
 finish_task_switch+0x11b/0x8b0 kernel/sched/core.c:5150
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x2607/0x8640 kernel/sched/core.c:6908
 preempt_schedule_common+0x33/0x80 kernel/sched/core.c:7092
 preempt_schedule+0x30/0x40 kernel/sched/core.c:7116
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
 _raw_spin_unlock_irqrestore+0x57/0x60 kernel/locking/spinlock.c:194
 unlock_hrtimer_base kernel/time/hrtimer.c:1021 [inline]
 hrtimer_try_to_cancel+0x8b0/0xae0 kernel/time/hrtimer.c:1368
 hrtimer_cancel+0x33/0xf0 kernel/time/hrtimer.c:1489
 schedule_hrtimeout_range_clock+0x16d/0x2f0 kernel/time/sleep_timeout.c:218
 schedule_hrtimeout_range+0x42/0x50 kernel/time/sleep_timeout.c:263
 poll_schedule_timeout fs/select.c:241 [inline]
 do_select+0x282b/0x2aa0 fs/select.c:603
 core_sys_select+0xa5a/0x10e0 fs/select.c:677
 do_pselect fs/select.c:759 [inline]
 __do_sys_pselect6 fs/select.c:798 [inline]
 __se_sys_pselect6+0x554/0x6b0 fs/select.c:789
 __x64_sys_pselect6+0x114/0x1a0 fs/select.c:789
 x64_sys_call+0xa5d/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:271
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable mmap_event created at:
 perf_event_mmap+0x47/0x2fe0 kernel/events/core.c:9894
 __mmap_complete mm/vma.c:2585 [inline]
 __mmap_region mm/vma.c:2768 [inline]
 mmap_region+0x4a79/0x6220 mm/vma.c:2837

CPU: 1 UID: 0 PID: 6279 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================


Tested on:

commit:         1f318b96 Linux 7.0-rc3
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d4694a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=242f02fcd3fbc8f3
dashboard link: https://syzkaller.appspot.com/bug?extid=4b1bd55fba6260160779
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1227175a580000