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BUG: KCSAN: data-race in ext4_mb_find_by_goal / mb_free_blocks

write to 0xffff8881013f96d4 of 4 bytes by task 4774 on cpu 0:
 mb_free_blocks+0x156/0xb40 fs/ext4/mballoc.c:1798
 ext4_mb_release_inode_pa+0x2f1/0x560 fs/ext4/mballoc.c:4694
 ext4_discard_preallocations+0x7a8/0xb40 fs/ext4/mballoc.c:4958
 ext4_truncate+0x71e/0xa80 fs/ext4/inode.c:4259
 ext4_truncate_failed_write fs/ext4/truncate.h:20 [inline]
 ext4_handle_inode_extension fs/ext4/file.c:358 [inline]
 ext4_dio_write_iter fs/ext4/file.c:574 [inline]
 ext4_file_write_iter+0x106c/0x11d0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881013f96d4 of 4 bytes by task 4773 on cpu 1:
 ext4_mb_find_by_goal+0x129/0x890 fs/ext4/mballoc.c:2202
 ext4_mb_regular_allocator+0x11c/0x2520 fs/ext4/mballoc.c:2635
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5514
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4241
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4428
 ext4_zero_range+0x309/0xa40 fs/ext4/extents.c:4540
 ext4_fallocate+0x226/0x4d0 fs/ext4/extents.c:4677
 vfs_fallocate+0x463/0x660 fs/open.c:311
 ksys_fallocate fs/open.c:334 [inline]
 __do_sys_fallocate fs/open.c:342 [inline]
 __se_sys_fallocate fs/open.c:340 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:340
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000fc0 -> 0x00000fff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4773 Comm: syz-executor.1 Not tainted 5.13.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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