linux-kernel - BUG: KCSAN: data-race in ext4_fill_raw_inode / setattr

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Message-ID: <8de8a931-e9a8-82f7-337f-d60ac80602fc@molgen.mpg.de>
Date:   Mon, 7 Feb 2022 20:13:51 +0100
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     "Theodore Y. Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-ext4@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org
Subject: BUG: KCSAN: data-race in ext4_fill_raw_inode / setattr_copy

Dear Linux folks,


Running Linux 5.17-rc2+ in QEMU 6.2.0, while running `apt install bluez 
bluez-obexd bash-completion` in the VM the Kernel Concurrency Sanitizer 
reports the race below.

     qemu-system-x86_64 -cpu host -smp cpus=3 -m 2G -enable-kvm -usb 
-device usb-host,vendorid=0x8087,productid=0x0a2a -drive 
file=/dev/shm/debian-64.img,format=raw,if=virtio -net nic -net 
user,hostfwd=tcp::22223-:22 -kernel /dev/shm/bzImage -append 
"root=/dev/vda1 rw quiet"

```
[  283.432792] 
==================================================================
[  283.433607] BUG: KCSAN: data-race in ext4_fill_raw_inode / setattr_copy

[  283.434585] read to 0xffffa07f951c9c50 of 8 bytes by task 7 on cpu 1:
[  283.435145]  ext4_fill_raw_inode+0x2d9/0xa40
[  283.435161]  ext4_mark_iloc_dirty+0x25b/0xbf0
[  283.435177]  __ext4_mark_inode_dirty+0xb3/0x3a0
[  283.435194]  __ext4_ext_dirty+0x115/0x130
[  283.435212]  ext4_ext_map_blocks+0x1a12/0x2740
[  283.435230]  ext4_map_blocks+0x2e1/0x9e0
[  283.435245]  ext4_convert_unwritten_extents+0x210/0x320
[  283.435265]  ext4_convert_unwritten_io_end_vec+0xad/0x130
[  283.435283]  ext4_end_io_rsv_work+0x180/0x310
[  283.435296]  process_one_work+0x477/0x7d0
[  283.435304]  worker_thread+0x2ec/0x810
[  283.435312]  kthread+0x16d/0x1a0
[  283.435322]  ret_from_fork+0x22/0x30

[  283.435599] write to 0xffffa07f951c9c50 of 16 bytes by task 1509 on 
cpu 0:
[  283.436138]  setattr_copy+0x94/0x160
[  283.436156]  ext4_setattr+0x30f/0xf20
[  283.436170]  notify_change+0x34d/0x640
[  283.436187]  vfs_utimes+0x225/0x3d0
[  283.436205]  do_utimes+0xab/0x110
[  283.436221]  __x64_sys_utimensat+0xa9/0x100
[  283.436240]  do_syscall_64+0x39/0x80
[  283.436257]  entry_SYSCALL_64_after_hwframe+0x44/0xae

[  283.436634] Reported by Kernel Concurrency Sanitizer on:
[  283.437154] CPU: 0 PID: 1509 Comm: dpkg Not tainted 
5.17.0-rc3-00369-gc67afd79c7ba #35
[  283.437173] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), 
BIOS 1.15.0-1 04/01/2014
[  283.437184] 
==================================================================
```

Please find the output of `dmesg` attached.


Kind regards,

Paul
View attachment "linux-5.17-rc3+-ext4_fill_raw_inode.txt" of type "text/plain" (63652 bytes)