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BUG: KCSAN: data-race in ktime_get / timekeeping_update_from_shadow

write to 0xffffffff893d24c8 of 304 bytes by interrupt on cpu 0:
 timekeeping_update_from_shadow+0x40d/0x440 kernel/time/timekeeping.c:835
 __timekeeping_advance+0xa68/0xc10 kernel/time/timekeeping.c:2614
 timekeeping_advance kernel/time/timekeeping.c:2622 [inline]
 update_wall_time+0x21/0x50 kernel/time/timekeeping.c:2632
 tick_do_update_jiffies64+0x169/0x1c0 kernel/time/tick-sched.c:149
 tick_sched_do_timer kernel/time/tick-sched.c:253 [inline]
 tick_nohz_handler+0x88/0x380 kernel/time/tick-sched.c:310
 __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
 __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096
 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 __import_iovec+0x0/0x530 lib/iov_iter.c:1255
 import_iovec+0x60/0x80 lib/iov_iter.c:1440
 copy_msghdr_from_user net/socket.c:2621 [inline]
 recvmsg_copy_msghdr net/socket.c:2870 [inline]
 ___sys_recvmsg+0x385/0x3a0 net/socket.c:2942
 do_recvmmsg+0x1e5/0x560 net/socket.c:3041
 __sys_recvmmsg net/socket.c:3115 [inline]
 __do_sys_recvmmsg net/socket.c:3138 [inline]
 __se_sys_recvmmsg net/socket.c:3131 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3131
 x64_sys_call+0x80f/0x3020 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff893d24d8 of 8 bytes by task 21829 on cpu 1:
 timekeeping_cycles_to_ns kernel/time/timekeeping.c:432 [inline]
 timekeeping_get_ns kernel/time/timekeeping.c:455 [inline]
 ktime_get+0xcf/0x240 kernel/time/timekeeping.c:973
 ktime_get_ns include/linux/timekeeping.h:175 [inline]
 blk_time_get_ns block/blk.h:722 [inline]
 blk_account_io_start+0x18c/0x450 block/blk-mq.c:1100
 blk_mq_bio_to_request block/blk-mq.c:2676 [inline]
 blk_mq_submit_bio+0xbb2/0x1150 block/blk-mq.c:3182
 __submit_bio+0x54/0x3d0 block/blk-core.c:673
 __submit_bio_noacct_mq block/blk-core.c:756 [inline]
 submit_bio_noacct_nocheck+0x153/0x620 block/blk-core.c:790
 submit_bio_noacct+0x700/0x920 block/blk-core.c:921
 submit_bio+0x2a4/0x2c0 block/blk-core.c:962
 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline]
 __bh_submit+0x2db/0x310 fs/buffer.c:1225
 bh_submit fs/buffer.c:1239 [inline]
 write_dirty_buffer+0xe0/0x110 fs/buffer.c:2778
 fat_sync_bhs+0x49/0x130 fs/fat/misc.c:354
 fat_alloc_clusters+0xac7/0xc40 fs/fat/fatent.c:546
 fat_add_cluster fs/fat/inode.c:108 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x252/0x5e0 fs/fat/inode.c:190
 __block_write_begin_int+0x400/0xf90 fs/buffer.c:2123
 block_write_begin fs/buffer.c:2234 [inline]
 cont_write_begin+0x5bf/0x920 fs/buffer.c:2596
 fat_write_begin+0x52/0xe0 fs/fat/inode.c:230
 generic_perform_write+0x186/0x490 mm/filemap.c:4358
 __generic_file_write_iter+0x9e/0x120 mm/filemap.c:4475
 generic_file_write_iter+0x77/0x1f0 mm/filemap.c:4501
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57d/0x990 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+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000235094b800d -> 0x000002350a9b3a38

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 21829 Comm: syz.6.4388 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
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