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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_single_inode

write to 0xffff8881066869a8 of 4 bytes by task 6006 on cpu 0:
 writeback_single_inode+0x14f/0x3f0 fs/fs-writeback.c:1798
 sync_inode_metadata+0x60/0x90 fs/fs-writeback.c:2883
 generic_buffers_fsync_noflush+0xd8/0x120 fs/buffer.c:610
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1c3/0x6c0 fs/ext4/fsync.c:147
 vfs_fsync_range+0x116/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:2976 [inline]
 ext4_buffered_write_iter+0x358/0x3c0 fs/ext4/file.c:305
 ext4_file_write_iter+0x3b2/0xf80 include/linux/fs.h:-1
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x79b/0x950 fs/read_write.c:684
 ksys_write+0xeb/0x1b0 fs/read_write.c:736
 __do_sys_write fs/read_write.c:747 [inline]
 __se_sys_write fs/read_write.c:744 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:744
 x64_sys_call+0x2a45/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881066869a8 of 4 bytes by task 6022 on cpu 1:
 __mark_inode_dirty+0x198/0x7e0 fs/fs-writeback.c:2549
 block_dirty_folio+0xf4/0x110 fs/buffer.c:746
 ext4_dirty_folio+0x7e/0xa0 fs/ext4/inode.c:3598
 folio_mark_dirty+0x7d/0xe0 mm/page-writeback.c:2874
 fault_dirty_shared_page+0x99/0x3b0 mm/memory.c:3317
 wp_page_shared mm/memory.c:3704 [inline]
 do_wp_page+0xf10/0x24e0 mm/memory.c:3907
 handle_pte_fault mm/memory.c:6013 [inline]
 __handle_mm_fault mm/memory.c:6140 [inline]
 handle_mm_fault+0xc6c/0x2e80 mm/memory.c:6309
 do_user_addr_fault arch/x86/mm/fault.c:1388 [inline]
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x296/0x6a0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
 rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:68
 copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline]
 copy_to_user_iter lib/iov_iter.c:25 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:300 [inline]
 iterate_and_advance include/linux/iov_iter.h:328 [inline]
 _copy_to_iter+0x144/0xd10 lib/iov_iter.c:185
 copy_to_iter include/linux/uio.h:220 [inline]
 get_random_bytes_user+0x131/0x290 drivers/char/random.c:472
 __do_sys_getrandom drivers/char/random.c:1414 [inline]
 __se_sys_getrandom drivers/char/random.c:1388 [inline]
 __x64_sys_getrandom+0xba/0x190 drivers/char/random.c:1388
 x64_sys_call+0x29cd/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:319
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000038 -> 0x00000022

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6022 Comm: syz.0.871 Not tainted 6.15.0-rc1-syzkaller-00325-g7cdabafc0012 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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