loop1: detected capacity change from 0 to 8192
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BUG: KCSAN: data-race in __mark_inode_dirty / __writeback_single_inode

read-write to 0xffff8881004c10b8 of 4 bytes by task 158 on cpu 1:
 __writeback_single_inode+0x1f4/0x850 fs/fs-writeback.c:1716
 writeback_sb_inodes+0x458/0xa10 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x276/0x650 fs/fs-writeback.c:2158
 wb_check_start_all fs/fs-writeback.c:2284 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0x510/0x960 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff8881004c10b8 of 4 bytes by task 5269 on cpu 0:
 __mark_inode_dirty+0x198/0x7e0 fs/fs-writeback.c:2549
 mark_buffer_dirty+0x149/0x230 fs/buffer.c:1199
 mark_buffer_dirty_inode+0x4c/0x1c0 fs/buffer.c:672
 fat16_ent_put+0x4f/0x60 fs/fat/fatent.c:184
 fat_alloc_clusters+0x4cb/0xa90 fs/fat/fatent.c:503
 fat_add_cluster fs/fat/inode.c:107 [inline]
 __fat_get_block fs/fat/inode.c:154 [inline]
 fat_get_block+0x25f/0x5e0 fs/fat/inode.c:189
 __block_write_begin_int+0x419/0xf90 fs/buffer.c:2116
 block_write_begin fs/buffer.c:2226 [inline]
 cont_write_begin+0x548/0x860 fs/buffer.c:2565
 fat_write_begin+0x51/0xe0 fs/fat/inode.c:228
 cont_expand_zero fs/buffer.c:2492 [inline]
 cont_write_begin+0x18d/0x860 fs/buffer.c:2555
 fat_write_begin+0x51/0xe0 fs/fat/inode.c:228
 generic_cont_expand_simple+0xaf/0x150 fs/buffer.c:2456
 fat_cont_expand+0x3a/0x160 fs/fat/file.c:223
 fat_setattr+0x2aa/0x840 fs/fat/file.c:513
 notify_change+0x85c/0x8e0 fs/attr.c:552
 do_truncate fs/open.c:65 [inline]
 do_ftruncate+0x32c/0x440 fs/open.c:192
 do_sys_ftruncate fs/open.c:207 [inline]
 __do_sys_ftruncate fs/open.c:212 [inline]
 __se_sys_ftruncate fs/open.c:210 [inline]
 __x64_sys_ftruncate+0x68/0xc0 fs/open.c:210
 x64_sys_call+0xa17/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:78
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00010022 -> 0x00000020

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5269 Comm: syz.1.671 Not tainted 6.14.0-syzkaller-10892-g4e82c87058f4 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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