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BUG: KCSAN: data-race in ps2_do_sendbyte / ps2_interrupt

write to 0xffff888103d8ce48 of 8 bytes by interrupt on cpu 0:
 ps2_interrupt+0x50d/0x550 drivers/input/serio/libps2.c:-1
 serio_interrupt+0x66/0xf0 drivers/input/serio/serio.c:967
 i8042_handle_data+0x388/0x680 drivers/input/serio/i8042.c:598
 i8042_interrupt+0x15/0x90 drivers/input/serio/i8042.c:605
 __handle_irq_event_percpu+0x8b/0x480 kernel/irq/handle.c:209
 handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
 handle_irq_event+0x64/0xf0 kernel/irq/handle.c:263
 handle_edge_irq+0x155/0x440 kernel/irq/chip.c:859
 generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
 handle_irq arch/x86/kernel/irq.c:209 [inline]
 call_irq_handler arch/x86/kernel/irq.c:-1 [inline]
 __common_interrupt+0x60/0xb0 arch/x86/kernel/irq.c:280
 common_interrupt+0x7e/0x90 arch/x86/kernel/irq.c:273
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
 is_atomic kernel/kcsan/core.c:264 [inline]
 should_watch kernel/kcsan/core.c:277 [inline]
 check_access kernel/kcsan/core.c:760 [inline]
 __tsan_read8+0x102/0x190 kernel/kcsan/core.c:1033
 folio_mark_dirty+0x70/0xd0 mm/page-writeback.c:2790
 shmem_write_end+0x34a/0x3c0 mm/shmem.c:3300
 generic_perform_write+0x314/0x490 mm/filemap.c:4395
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3443
 __kernel_write_iter+0x30f/0x590 fs/read_write.c:621
 dump_write_iter fs/coredump.c:1358 [inline]
 dump_emit_page fs/coredump.c:1531 [inline]
 dump_user_range+0x761/0x920 fs/coredump.c:1599
 elf_core_dump+0x2183/0x2310 fs/binfmt_elf.c:2106
 coredump_write fs/coredump.c:1150 [inline]
 do_coredump fs/coredump.c:1235 [inline]
 vfs_coredump+0x42a5/0x4860 fs/coredump.c:1310
 get_signal+0xd33/0xf10 kernel/signal.c:3097
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x14d/0x610 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

read to 0xffff888103d8ce48 of 8 bytes by task 3564 on cpu 1:
 ps2_do_sendbyte+0x17e/0x320 drivers/input/serio/libps2.c:65
 __ps2_command+0x364/0xaa0 drivers/input/serio/libps2.c:322
 ps2_command+0x52/0x90 drivers/input/serio/libps2.c:403
 synaptics_detect+0x6e/0x130 drivers/input/mouse/synaptics.c:103
 psmouse_do_detect drivers/input/mouse/psmouse-base.c:995 [inline]
 psmouse_extensions+0x4df/0x960 drivers/input/mouse/psmouse-base.c:1090
 __psmouse_reconnect+0x3dd/0x880 drivers/input/mouse/psmouse-base.c:1685
 psmouse_reconnect+0x23/0x40 drivers/input/mouse/psmouse-base.c:1723
 serio_reconnect_driver drivers/input/serio/serio.c:52 [inline]
 serio_reconnect_port drivers/input/serio/serio.c:558 [inline]
 serio_reconnect_subtree drivers/input/serio/serio.c:578 [inline]
 drvctl_store+0x2ac/0xc20 drivers/input/serio/serio.c:364
 dev_attr_store+0x4a/0x70 drivers/base/core.c:2509
 sysfs_kf_write+0xfe/0x120 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x1d2/0x2e0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57f/0x9a0 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000001 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3564 Comm: syz.1.15 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
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