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BUG: KCSAN: data-race in __d_instantiate / path_lookupat

read-write to 0xffff8881004f23c0 of 4 bytes by task 3644 on cpu 0:
 fsnotify_update_flags include/linux/fsnotify_backend.h:-1 [inline]
 __d_instantiate+0x2a8/0x390 fs/dcache.c:2158
 d_instantiate_new+0x68/0xf0 fs/dcache.c:2204
 ext4_add_nondir+0x187/0x1b0 fs/ext4/namei.c:2796
 ext4_symlink+0x58f/0x660 fs/ext4/namei.c:3435
 vfs_symlink+0xfd/0x220 fs/namei.c:5794
 filename_symlinkat+0xe8/0x2b0 fs/namei.c:5819
 __do_sys_symlink fs/namei.c:5846 [inline]
 __se_sys_symlink+0x42/0x1b0 fs/namei.c:5842
 __x64_sys_symlink+0x31/0x40 fs/namei.c:5842
 x64_sys_call+0x211f/0x2550 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881004f23c0 of 4 bytes by task 3645 on cpu 1:
 d_managed include/linux/dcache.h:433 [inline]
 step_into fs/namei.c:2140 [inline]
 walk_component fs/namei.c:2288 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x19b/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x1d41/0x2550 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00040040 -> 0x00340040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3645 Comm: syz-executor101 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88810061c600 of 4 bytes by task 3644 on cpu 0:
 fsnotify_update_flags include/linux/fsnotify_backend.h:-1 [inline]
 __d_instantiate+0x2a8/0x390 fs/dcache.c:2158
 d_instantiate_new+0x68/0xf0 fs/dcache.c:2204
 ext4_add_nondir+0x187/0x1b0 fs/ext4/namei.c:2796
 ext4_symlink+0x58f/0x660 fs/ext4/namei.c:3435
 vfs_symlink+0xfd/0x220 fs/namei.c:5794
 filename_symlinkat+0xe8/0x2b0 fs/namei.c:5819
 __do_sys_symlink fs/namei.c:5846 [inline]
 __se_sys_symlink+0x42/0x1b0 fs/namei.c:5842
 __x64_sys_symlink+0x31/0x40 fs/namei.c:5842
 x64_sys_call+0x211f/0x2550 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810061c600 of 4 bytes by task 3645 on cpu 1:
 d_revalidate fs/namei.c:1034 [inline]
 lookup_fast+0xf1/0x320 fs/namei.c:1868
 walk_component fs/namei.c:2278 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x120/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x1d41/0x2550 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00040040 -> 0x00340040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3645 Comm: syz-executor101 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================
==================================================================
BUG: KCSAN: data-race in dont_mount / path_lookupat

read-write to 0xffff888105d61000 of 4 bytes by task 3644 on cpu 0:
 dont_mount+0x2a/0x40 include/linux/dcache.h:412
 vfs_unlink+0x202/0x490 fs/namei.c:5651
 filename_unlinkat+0x1dc/0x410 fs/namei.c:5719
 __do_sys_unlink fs/namei.c:5754 [inline]
 __se_sys_unlink+0x2b/0xe0 fs/namei.c:5751
 __x64_sys_unlink+0x1f/0x30 fs/namei.c:5751
 x64_sys_call+0x18ee/0x2550 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105d61000 of 4 bytes by task 3645 on cpu 1:
 d_managed include/linux/dcache.h:433 [inline]
 step_into fs/namei.c:2140 [inline]
 walk_component fs/namei.c:2288 [inline]
 lookup_last fs/namei.c:2789 [inline]
 path_lookupat+0x19b/0x4c0 fs/namei.c:2813
 filename_lookup+0x18f/0x390 fs/namei.c:2842
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x1d41/0x2550 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00340040 -> 0x00040040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3645 Comm: syz-executor101 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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