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KCSAN: data-race in mnt_want_write / umount_tree

Status: auto-closed as invalid on 2021/06/10 21:09
Subsystems: fs
[Documentation on labels]
First crash: 1057d, last: 1057d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in mnt_want_write / umount_tree

write to 0xffff8881335e5e30 of 4 bytes by task 2049 on cpu 0:
 umount_tree+0x89/0x8f0 fs/namespace.c:1509
 dissolve_on_fput+0xaf/0x200 fs/namespace.c:1922
 __fput+0x4b1/0x4e0 fs/file_table.c:295
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881335e5e30 of 4 bytes by task 2067 on cpu 1:
 __mnt_is_readonly fs/namespace.c:269 [inline]
 mnt_is_readonly fs/namespace.c:313 [inline]
 __mnt_want_write fs/namespace.c:353 [inline]
 mnt_want_write+0x117/0x220 fs/namespace.c:376
 filename_create+0x92/0x3c0 fs/namei.c:3587
 user_path_create fs/namei.c:3650 [inline]
 do_mknodat+0xbf/0x320 fs/namei.c:3731
 __do_sys_mknodat fs/namei.c:3770 [inline]
 __se_sys_mknodat fs/namei.c:3767 [inline]
 __x64_sys_mknodat+0x4e/0x60 fs/namei.c:3767
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2067 Comm: syz-executor.0 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/05/06 21:06 upstream 8404c9fbc84b 06585184 .config console log report info ci2-upstream-kcsan-gce KCSAN: data-race in mnt_want_write / umount_tree
* Struck through repros no longer work on HEAD.