syzbot

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BUG: KCSAN: data-race in drop_nlink / vfs_coredump

write to 0xffff888101601520 of 4 bytes by task 8062 on cpu 1:
 drop_nlink+0x3d/0xa0 fs/inode.c:418
 __simple_unlink fs/libfs.c:792 [inline]
 simple_unlink+0x60/0x80 fs/libfs.c:806
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 vfs_unlink+0x28b/0x440 fs/namei.c:5378
 do_unlinkat+0x1e2/0x4b0 fs/namei.c:5448
 coredump_file fs/coredump.c:902 [inline]
 do_coredump fs/coredump.c:1099 [inline]
 vfs_coredump+0x1553/0x3120 fs/coredump.c:1200
 get_signal+0xd7b/0xf60 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0xf7/0x510 kernel/entry/common.c:196
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

read to 0xffff888101601520 of 4 bytes by task 8061 on cpu 0:
 coredump_file fs/coredump.c:937 [inline]
 do_coredump fs/coredump.c:1099 [inline]
 vfs_coredump+0x165f/0x3120 fs/coredump.c:1200
 get_signal+0xd7b/0xf60 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x450 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0xf7/0x510 kernel/entry/common.c:196
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8061 Comm: syz.0.1117 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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