syzbot

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BUG: KCSAN: data-race in iput / writeback_single_inode

write to 0xffff8881047ef428 of 4 bytes by task 7691 on cpu 1:
 writeback_single_inode+0x14f/0x3f0 fs/fs-writeback.c:1776
 sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2849
 __generic_file_fsync+0xed/0x140 fs/libfs.c:1539
 fat_file_fsync+0x46/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x116/0x130 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2870 [inline]
 generic_file_write_iter+0x185/0x1c0 mm/filemap.c:4156
 __kernel_write_iter+0x24b/0x4e0 fs/read_write.c:616
 __kernel_write+0x90/0xc0 fs/read_write.c:636
 __dump_emit fs/coredump.c:816 [inline]
 dump_emit+0x1a8/0x270 fs/coredump.c:853
 writenote+0x10a/0x190 fs/binfmt_elf.c:1458
 write_note_info fs/binfmt_elf.c:1951 [inline]
 elf_core_dump+0x18c0/0x1c60 fs/binfmt_elf.c:2103
 do_coredump+0xfa7/0x1800 fs/coredump.c:767
 get_signal+0xdc0/0x1070 kernel/signal.c:2902
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x9a/0x130 kernel/entry/common.c:231
 irqentry_exit+0x12/0x50 kernel/entry/common.c:334
 exc_general_protection+0x33d/0x4d0 arch/x86/kernel/traps.c:693
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

read to 0xffff8881047ef428 of 4 bytes by task 4062 on cpu 0:
 iput+0x32/0x5b0 fs/inode.c:1899
 __fat_readdir+0xa33/0xd70 fs/fat/dir.c:686
 fat_readdir+0x2f/0x40 fs/fat/dir.c:716
 iterate_dir+0x11d/0x310 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:407 [inline]
 __se_sys_getdents64+0x88/0x1a0 fs/readdir.c:392
 __x64_sys_getdents64+0x43/0x50 fs/readdir.c:392
 x64_sys_call+0x29b3/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:218
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000038 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4062 Comm: syz-executor Not tainted 6.11.0-syzkaller-04744-gbdf56c7580d2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
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