syzbot

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BUG: KCSAN: data-race in generic_fillattr / inode_add_bytes

read-write to 0xffff88811ac2cca8 of 8 bytes by task 20611 on cpu 1:
 __inode_add_bytes fs/stat.c:910 [inline]
 inode_add_bytes+0x47/0xe0 fs/stat.c:923
 __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:1923 [inline]
 shmem_get_folio_gfp+0x5a7/0xd40 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0xa8/0x190 mm/shmem.c:3289
 generic_perform_write+0x181/0x490 mm/filemap.c:4103
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3464
 __kernel_write_iter+0x253/0x4c0 fs/read_write.c:617
 dump_emit_page fs/coredump.c:885 [inline]
 dump_user_range+0x5f4/0x8d0 fs/coredump.c:959
 elf_core_dump+0x1dc2/0x1f80 fs/binfmt_elf.c:2151
 do_coredump+0x1836/0x1f40 fs/coredump.c:759
 get_signal+0xd85/0xf70 kernel/signal.c:3019
 arch_do_signal_or_restart+0x97/0x480 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:329 [inline]
 irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:231
 irqentry_exit+0x12/0x50 kernel/entry/common.c:334
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff88811ac2cca8 of 8 bytes by task 3319 on cpu 0:
 generic_fillattr+0x27d/0x340 fs/stat.c:106
 shmem_getattr+0x181/0x200 mm/shmem.c:1262
 vfs_getattr_nosec+0x143/0x1e0 fs/stat.c:210
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:296 [inline]
 vfs_statx+0x11a/0x380 fs/stat.c:353
 vfs_fstatat+0xe1/0x160 fs/stat.c:372
 __do_sys_newfstatat fs/stat.c:536 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:530
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:530
 x64_sys_call+0x2c22/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000008e0 -> 0x00000000000008f8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3319 Comm: syz-executor Not tainted 6.15.0-rc6-syzkaller-00105-g088d13246a46 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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