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BUG: KCSAN: data-race in ext4_setattr / generic_file_buffered_read

write to 0xffff8880bb672838 of 8 bytes by task 25061 on cpu 1:
 i_size_write include/linux/fs.h:896 [inline]
 ext4_setattr+0xd61/0xec0 fs/ext4/inode.c:5386
 notify_change+0x7d4/0xa20 fs/attr.c:336
 do_truncate+0xe0/0x120 fs/open.c:64
 handle_truncate fs/namei.c:2901 [inline]
 do_open fs/namei.c:3247 [inline]
 path_openat+0x1a4c/0x20e0 fs/namei.c:3360
 do_filp_open+0xbd/0x1d0 fs/namei.c:3387
 do_sys_openat2+0x33c/0x4a0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_creat fs/open.c:1263 [inline]
 __se_sys_creat fs/open.c:1261 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1261
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880bb672838 of 8 bytes by task 25104 on cpu 0:
 i_size_read include/linux/fs.h:874 [inline]
 generic_file_buffered_read+0xf71/0x1800 mm/filemap.c:2088
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2307
 ext4_file_read_iter+0x2d6/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1901 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 __vfs_read+0x2d5/0x330 fs/read_write.c:428
 integrity_kernel_read+0xb4/0x100 security/integrity/iint.c:200
 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:484 [inline]
 ima_calc_file_shash security/integrity/ima/ima_crypto.c:515 [inline]
 ima_calc_file_hash+0x9bf/0x13e0 security/integrity/ima/ima_crypto.c:580
 ima_collect_measurement+0x168/0x310 security/integrity/ima/ima_api.c:250
 process_measurement+0xa65/0x10d0 security/integrity/ima/ima_main.c:324
 ima_file_check+0x75/0xa0 security/integrity/ima/ima_main.c:492
 do_open fs/namei.c:3245 [inline]
 path_openat+0x18a2/0x20e0 fs/namei.c:3360
 do_filp_open+0xbd/0x1d0 fs/namei.c:3387
 do_sys_openat2+0x33c/0x4a0 fs/open.c:1179
 do_sys_open fs/open.c:1195 [inline]
 ksys_open include/linux/syscalls.h:1388 [inline]
 __do_sys_open fs/open.c:1201 [inline]
 __se_sys_open fs/open.c:1199 [inline]
 __x64_sys_open+0xe2/0x110 fs/open.c:1199
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25104 Comm: syz-executor.1 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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