syzbot

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BUG: KCSAN: data-race in __mark_inode_dirty / __writeback_single_inode

read-write to 0xffff8881007701b8 of 4 bytes by task 51 on cpu 1:
 __writeback_single_inode+0x1e3/0x7c0 fs/fs-writeback.c:1716
 writeback_sb_inodes+0x480/0xa20 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x94/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x266/0x5c0 fs/fs-writeback.c:2158
 wb_check_start_all fs/fs-writeback.c:2284 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0x4c9/0x910 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 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 to 0xffff8881007701b8 of 4 bytes by task 4165 on cpu 0:
 __mark_inode_dirty+0x52/0x760 fs/fs-writeback.c:2509
 generic_update_time fs/inode.c:2064 [inline]
 inode_update_time fs/inode.c:2077 [inline]
 __file_update_time fs/inode.c:2305 [inline]
 file_update_time+0x288/0x2b0 fs/inode.c:2335
 ext4_page_mkwrite+0x18b/0xba0 fs/ext4/inode.c:6221
 do_page_mkwrite mm/memory.c:3287 [inline]
 wp_page_shared mm/memory.c:3688 [inline]
 do_wp_page+0xe2d/0x23e0 mm/memory.c:3907
 handle_pte_fault mm/memory.c:6013 [inline]
 __handle_mm_fault mm/memory.c:6140 [inline]
 handle_mm_fault+0x6dc/0x2ae0 mm/memory.c:6309
 do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1337
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x54/0xc0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x0001002a -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4165 Comm: syz.0.231 Not tainted 6.15.0-rc6-syzkaller-00052-g9f35e33144ae #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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