syzbot

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BUG: KCSAN: data-race in generic_fillattr / inode_add_bytes

read-write to 0xffff8881268d8f90 of 8 bytes by task 11125 on cpu 0:
 __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:1695
 dquot_alloc_space_nodirty include/linux/quotaops.h:299 [inline]
 dquot_alloc_block_nodirty include/linux/quotaops.h:326 [inline]
 shmem_inode_acct_blocks+0x129/0x240 mm/shmem.c:237
 shmem_alloc_and_add_folio mm/shmem.c:1977 [inline]
 shmem_get_folio_gfp+0x5a7/0xd60 mm/shmem.c:2597
 shmem_get_folio mm/shmem.c:2703 [inline]
 shmem_write_begin+0xa8/0x190 mm/shmem.c:3353
 generic_perform_write+0x184/0x490 mm/filemap.c:4175
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3528
 __kernel_write_iter+0x2d6/0x540 fs/read_write.c:619
 dump_emit_page fs/coredump.c:1296 [inline]
 dump_user_range+0x61e/0x8f0 fs/coredump.c:1370
 elf_core_dump+0x1e00/0x1f90 fs/binfmt_elf.c:2085
 coredump_write+0xb0d/0xe30 fs/coredump.c:1049
 vfs_coredump+0x142f/0x20c0 fs/coredump.c:1168
 get_signal+0xd85/0xf70 kernel/signal.c:3019
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881268d8f90 of 8 bytes by task 3315 on cpu 1:
 generic_fillattr+0x27d/0x340 fs/stat.c:106
 shmem_getattr+0x181/0x200 mm/shmem.c:1294
 vfs_getattr_nosec+0x143/0x1e0 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+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:536
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
 x64_sys_call+0x135a/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000006e8 -> 0x0000000000000700

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3315 Comm: syz-executor Tainted: G        W           6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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