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BUG: KCSAN: data-race in ext4_mb_find_by_goal / mb_free_blocks

write to 0xffff888101790a94 of 4 bytes by task 13876 on cpu 1:
 mb_free_blocks+0x156/0xb40 fs/ext4/mballoc.c:1798
 ext4_mb_release_inode_pa+0x2f1/0x560 fs/ext4/mballoc.c:4695
 ext4_discard_preallocations+0x7a8/0xb40 fs/ext4/mballoc.c:4959
 ext4_move_extents+0x5cc/0x2250 fs/ext4/move_extent.c:690
 __ext4_ioctl fs/ext4/ioctl.c:988 [inline]
 ext4_ioctl+0x14d5/0x2100 fs/ext4/ioctl.c:1277
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101790a94 of 4 bytes by task 13868 on cpu 0:
 ext4_mb_find_by_goal+0x129/0x890 fs/ext4/mballoc.c:2203
 ext4_mb_regular_allocator+0x11c/0x2520 fs/ext4/mballoc.c:2636
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5515
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4712
 vfs_fallocate+0x463/0x660 fs/open.c:311
 file_ioctl fs/ioctl.c:497 [inline]
 do_vfs_ioctl+0x1322/0x1410 fs/ioctl.c:1048
 __do_sys_ioctl fs/ioctl.c:1067 [inline]
 __se_sys_ioctl+0x83/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000001da -> 0x000001e9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13868 Comm: syz-executor.1 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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