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BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick

read-write to 0xffff888100e536b8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x63/0x240 kernel/workqueue.c:1474
 sched_tick+0xd2/0x110 kernel/sched/core.c:5609
 update_process_times+0x15a/0x180 kernel/time/timer.c:2524
 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:1691 [inline]
 __hrtimer_run_queues+0x20d/0x5e0 kernel/time/hrtimer.c:1755
 hrtimer_interrupt+0x210/0x7b0 kernel/time/hrtimer.c:1817
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1026 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1a0 arch/x86/kernel/apic/apic.c:1043
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
 sysvec_apic_timer_interrupt+0x6e/0x80 arch/x86/kernel/apic/apic.c:1037
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 kcsan_setup_watchpoint+0x404/0x410 kernel/kcsan/core.c:705
 max_index lib/xarray.c:435 [inline]
 xas_find_marked+0x53a/0x660 lib/xarray.c:1340
 find_get_entry+0x54/0x390 mm/filemap.c:1994
 filemap_get_folios_tag+0x9e/0x210 mm/filemap.c:2261
 mpage_prepare_extent_to_map+0x329/0xb80 fs/ext4/inode.c:2437
 ext4_do_writepages+0x6ea/0x2130 fs/ext4/inode.c:2677
 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2813
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1658
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1954
 wb_writeback+0x262/0x640 fs/fs-writeback.c:2134
 wb_do_writeback fs/fs-writeback.c:2281 [inline]
 wb_workfn+0x1a8/0x940 fs/fs-writeback.c:2321
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read-write to 0xffff888100e536b8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x63/0x240 kernel/workqueue.c:1474
 sched_tick+0xd2/0x110 kernel/sched/core.c:5609
 update_process_times+0x15a/0x180 kernel/time/timer.c:2524
 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:1691 [inline]
 __hrtimer_run_queues+0x20d/0x5e0 kernel/time/hrtimer.c:1755
 hrtimer_interrupt+0x210/0x7b0 kernel/time/hrtimer.c:1817
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1026 [inline]
 __sysvec_apic_timer_interrupt+0x5c/0x1a0 arch/x86/kernel/apic/apic.c:1043
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1037 [inline]
 sysvec_apic_timer_interrupt+0x6e/0x80 arch/x86/kernel/apic/apic.c:1037
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
 __find_get_block+0x187/0x8a0
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x139/0x3b0 fs/buffer.c:1437
 sb_getblk_gfp include/linux/buffer_head.h:392 [inline]
 __read_extent_tree_block+0xb0/0x480 fs/ext4/extents.c:565
 ext4_find_extent+0x501/0x7c0 fs/ext4/extents.c:938
 ext4_ext_map_blocks+0x11f/0x35c0 fs/ext4/extents.c:4205
 ext4_map_create_blocks fs/ext4/inode.c:516 [inline]
 ext4_map_blocks+0x592/0xcf0 fs/ext4/inode.c:702
 mpage_map_one_extent fs/ext4/inode.c:2208 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2261 [inline]
 ext4_do_writepages+0x14c3/0x2130 fs/ext4/inode.c:2724
 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2813
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1658
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1954
 wb_writeback+0x262/0x640 fs/fs-writeback.c:2134
 wb_do_writeback fs/fs-writeback.c:2281 [inline]
 wb_workfn+0x1a8/0x940 fs/fs-writeback.c:2321
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x0000000001f03740 -> 0x0000000001f05e50

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 14327 Comm: kworker/u8:21 Not tainted 6.11.0-syzkaller-12113-ge7ed34365879 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: writeback wb_workfn (flush-7:4)
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