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BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick

read-write to 0xffff88810107f4b8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x63/0x240 kernel/workqueue.c:1474
 sched_tick+0x116/0x260 kernel/sched/core.c:5677
 update_process_times+0x161/0x190 kernel/time/timer.c:2520
 tick_sched_handle kernel/time/tick-sched.c:276 [inline]
 tick_nohz_handler+0x250/0x2d0 kernel/time/tick-sched.c:297
 __run_hrtimer kernel/time/hrtimer.c:1791 [inline]
 __hrtimer_run_queues+0x221/0x5f0 kernel/time/hrtimer.c:1855
 hrtimer_interrupt+0x235/0x4a0 kernel/time/hrtimer.c:1917
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x6e/0x80 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 ext4_map_blocks+0x95/0xdf0 fs/ext4/inode.c:619
 mpage_map_one_extent fs/ext4/inode.c:2221 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2274 [inline]
 ext4_do_writepages+0x14ef/0x21d0 fs/ext4/inode.c:2736
 ext4_writepages+0x183/0x320 fs/ext4/inode.c:2826
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2687
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x458/0xa10 fs/fs-writeback.c:1976
 wb_writeback+0x264/0x650 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x1aa/0x960 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff88810107f4b8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x63/0x240 kernel/workqueue.c:1474
 sched_tick+0x116/0x260 kernel/sched/core.c:5677
 update_process_times+0x161/0x190 kernel/time/timer.c:2520
 tick_sched_handle kernel/time/tick-sched.c:276 [inline]
 tick_nohz_handler+0x250/0x2d0 kernel/time/tick-sched.c:297
 __run_hrtimer kernel/time/hrtimer.c:1791 [inline]
 __hrtimer_run_queues+0x221/0x5f0 kernel/time/hrtimer.c:1855
 hrtimer_interrupt+0x235/0x4a0 kernel/time/hrtimer.c:1917
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1d0 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x6e/0x80 arch/x86/kernel/apic/apic.c:1049
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 should_watch kernel/kcsan/core.c:280 [inline]
 check_access kernel/kcsan/core.c:752 [inline]
 __tsan_read8+0x116/0x180 kernel/kcsan/core.c:1025
 xas_find_marked+0x92/0x660 lib/xarray.c:1337
 find_get_entry+0x54/0x390 mm/filemap.c:2039
 filemap_get_folios_tag+0x13e/0x220 mm/filemap.c:2306
 mpage_prepare_extent_to_map+0x332/0xb80 fs/ext4/inode.c:2450
 ext4_do_writepages+0x705/0x21d0 fs/ext4/inode.c:2689
 ext4_writepages+0x183/0x320 fs/ext4/inode.c:2826
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2687
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x458/0xa10 fs/fs-writeback.c:1976
 wb_writeback+0x264/0x650 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x1aa/0x960 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x000000001a3941c0 -> 0x000000001a3968d0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 1608 Comm: kworker/u8:5 Not tainted 6.14.0-syzkaller-10764-gaa918db707fb #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:2)
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