syzbot

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BUG: KCSAN: data-race in ext4_remount / new_sync_read

read to 0xffff888126f66050 of 8 bytes by task 12001 on cpu 1:
 iocb_flags include/linux/fs.h:3396 [inline]
 init_sync_kiocb include/linux/fs.h:2075 [inline]
 new_sync_read+0x1a3/0x4f0 fs/read_write.c:410
 __vfs_read+0xb1/0xc0 fs/read_write.c:427
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 kernel_read+0x79/0xb0 fs/read_write.c:440
 elf_read fs/binfmt_elf.c:411 [inline]
 load_elf_binary+0x423/0x2ef0 fs/binfmt_elf.c:772
 search_binary_handler fs/exec.c:1658 [inline]
 search_binary_handler+0x127/0x420 fs/exec.c:1635
 exec_binprm fs/exec.c:1701 [inline]
 __do_execve_file.isra.0+0xb6a/0x1140 fs/exec.c:1821
 do_execveat_common fs/exec.c:1867 [inline]
 do_execve fs/exec.c:1884 [inline]
 __do_sys_execve fs/exec.c:1960 [inline]
 __se_sys_execve fs/exec.c:1955 [inline]
 __x64_sys_execve+0x62/0x80 fs/exec.c:1955
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888126f66050 of 8 bytes by task 11991 on cpu 0:
 ext4_remount+0x331/0x13a0 fs/ext4/super.c:5511
 legacy_reconfigure+0x9a/0xc0 fs/fs_context.c:670
 reconfigure_super+0x36a/0x570 fs/super.c:955
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1136/0x14f0 fs/namespace.c:3133
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11991 Comm: syz-executor.2 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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