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BUG: KCSAN: data-race in generic_fillattr / inode_add_bytes

read-write to 0xffff88811b194ca8 of 8 bytes by task 16155 on cpu 1:
 __inode_add_bytes fs/stat.c:919 [inline]
 inode_add_bytes+0x47/0xe0 fs/stat.c:932
 __dquot_alloc_space+0x180/0x8a0 fs/quota/dquot.c:1698
 dquot_alloc_space_nodirty include/linux/quotaops.h:299 [inline]
 dquot_alloc_block_nodirty include/linux/quotaops.h:326 [inline]
 shmem_inode_acct_blocks+0x126/0x230 mm/shmem.c:236
 shmem_alloc_and_add_folio mm/shmem.c:1962 [inline]
 shmem_get_folio_gfp+0x5a7/0xd50 mm/shmem.c:2556
 shmem_get_folio mm/shmem.c:2662 [inline]
 shmem_write_begin+0xfc/0x1f0 mm/shmem.c:3315
 generic_perform_write+0x184/0x490 mm/filemap.c:4314
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3490
 iter_file_splice_write+0x66b/0xa20 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x156/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x312/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2db1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b194ca8 of 8 bytes by task 16152 on cpu 0:
 generic_fillattr+0x27d/0x340 fs/stat.c:106
 shmem_getattr+0x181/0x200 mm/shmem.c:1274
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr fs/stat.c:262 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x113/0x390 fs/stat.c:356
 vfs_fstatat fs/stat.c:375 [inline]
 vfs_lstat include/linux/fs.h:3161 [inline]
 __do_sys_newlstat fs/stat.c:528 [inline]
 __se_sys_newlstat+0x69/0x280 fs/stat.c:522
 __x64_sys_newlstat+0x31/0x40 fs/stat.c:522
 x64_sys_call+0x1f49/0x3000 arch/x86/include/generated/asm/syscalls_64.h:7
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000001cf8 -> 0x0000000000001d08

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16152 Comm: syz.8.3974 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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