syzbot

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BUG: KCSAN: data-race in ext4_mpage_readpages / file_remove_privs

write to 0xffff88808b09e0f4 of 4 bytes by task 9979 on cpu 0:
 inode_has_no_xattr include/linux/fs.h:3574 [inline]
 file_remove_privs+0x2e0/0x370 fs/inode.c:1943
 file_modified+0x16/0x80 fs/inode.c:2006
 ext4_write_checks fs/ext4/file.c:249 [inline]
 ext4_buffered_write_iter+0x1d0/0x3b0 fs/ext4/file.c:265
 ext4_file_write_iter+0x76f/0x1010 include/linux/fs.h:805
 call_write_iter include/linux/fs.h:1908 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x607/0x690 fs/read_write.c:578
 ksys_write+0xce/0x180 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:640
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88808b09e0f4 of 4 bytes by task 9967 on cpu 1:
 ext4_readpage_limit fs/ext4/readpage.c:218 [inline]
 ext4_mpage_readpages+0x3d5/0x1380 fs/ext4/readpage.c:263
 ext4_readahead+0x93/0xa0 fs/ext4/inode.c:3242
 read_pages+0xa0/0x6b0 mm/readahead.c:130
 page_cache_readahead_unbounded+0x3ef/0x440 mm/readahead.c:244
 ondemand_readahead+0x4e4/0x6e0 mm/readahead.c:273
 page_cache_async_readahead+0x1c6/0x1e0 mm/readahead.c:631
 generic_file_buffered_read+0x35a/0x19e0 mm/filemap.c:2045
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2326
 ext4_file_read_iter+0x2d6/0x420 fs/ext4/file.c:74
 call_read_iter include/linux/fs.h:1902 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 __kernel_read+0x511/0x580 fs/read_write.c:438
 integrity_kernel_read+0x4c/0x70 security/integrity/iint.c:191
 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:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9967 Comm: syz-executor.1 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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