BUG: KCSAN: data-race in mutex_spin_on_owner+0xef/0x1b0

BUG: KCSAN: data-race in mutex_spin_on_owner+0xef/0x1b0

[Naresh Kamboju]

LKFT started testing KCSAN enabled kernel from the linux next tree.
Here we have found BUG: KCSAN: data-race in mutex_spin_on_owner
and several more KCSAN BUGs.

This report is from an x86_64 machine clang-11 linux next 20201201.
Since we are running for the first time we do not call this regression.

[    4.745161] usbcore: registered new interface driver cdc_ether
[    4.751281] ==================================================================
[    4.756653] usbcore: registered new interface driver net1080
[    4.752139] BUG: KCSAN: data-race in mutex_spin_on_owner+0xef/0x1b0
[    4.752139]
[    4.752139] race at unknown origin, with read to 0xffff90a80098b034
of 4 bytes by task 252 on cpu 1:
[    4.769781] usbcore: registered new interface driver cdc_subset
[    4.752139]  mutex_spin_on_owner+0xef/0x1b0
[    4.752139]  __mutex_lock+0x69d/0x820
[    4.752139]  __mutex_lock_slowpath+0x13/0x20
[    4.781657] usbcore: registered new interface driver zaurus
[    4.752139]  mutex_lock+0x9d/0xb0
[    4.752139]  ata_eh_acquire+0x2e/0x80
[    4.752139]  ata_msleep+0x91/0xa0
[    4.792317] usbcore: registered new interface driver cdc_ncm
[    4.752139]  sata_link_debounce+0x1ad/0x2f0
[    4.752139]  sata_link_resume+0x32f/0x4a0
[    4.752139]  sata_link_hardreset+0x456/0x640
[    4.802369] usbcore: registered new interface driver r8153_ecm
[    4.752139]  ahci_do_hardreset+0x177/0x230
[    4.752139]  ahci_hardreset+0x23/0x40
[    4.752139]  ata_eh_reset+0x91e/0x1bb0
[    4.810641] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[    4.810482]  ata_eh_recover+0x79b/0x2bd0
[    4.810482]  sata_pmp_error_handler+0x7d1/0x1340
[    4.810482]  ahci_error_handler+0x7c/0xc0
[    4.819247] ehci-pci: EHCI PCI platform driver
[    4.810482]  ata_scsi_port_error_handler+0x708/0xd30
[    4.810482]  ata_scsi_error+0x128/0x160
[    4.826321] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[    4.810482]  scsi_error_handler+0x26d/0x700
[    4.810482]  kthread+0x20b/0x220
[    4.836069] ohci-pci: OHCI PCI platform driver
[    4.810482]  ret_from_fork+0x22/0x30
[    4.810482]
[    4.844397] uhci_hcd: USB Universal Host Controller Interface driver
[    4.810482] Reported by Kernel Concurrency Sanitizer on:
[    4.810482] CPU: 1 PID: 252 Comm: scsi_eh_1 Not tainted
5.10.0-rc6-next-20201201 #2
[    4.810482] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
2.2 05/23/2018
[    4.855343] xhci_hcd 0000:00:14.0: xHCI Host Controller
[    4.810482] ==================================================================

metadata:
    git_repo: https://gitlab.com/aroxell/lkft-linux-next
    target_arch: x86
    toolchain: clang-11
    git_describe: next-20201201
    kernel_version: 5.10.0-rc6
    download_url: https://builds.tuxbuild.com/1l8eiWgGMi6W4aDobjAAlOleFVl/

full test log link,
https://lkft.validation.linaro.org/scheduler/job/2002643#L831

-- 
Linaro LKFT
https://lkft.linaro.org

Re: BUG: KCSAN: data-race in mutex_spin_on_owner+0xef/0x1b0

[Peter Zijlstra]

On Fri, Dec 04, 2020 at 11:51:39PM +0530, Naresh Kamboju wrote:
> LKFT started testing KCSAN enabled kernel from the linux next tree.
> Here we have found BUG: KCSAN: data-race in mutex_spin_on_owner
> and several more KCSAN BUGs.
> 
> This report is from an x86_64 machine clang-11 linux next 20201201.
> Since we are running for the first time we do not call this regression.
> 
> [    4.745161] usbcore: registered new interface driver cdc_ether
> [    4.751281] ==================================================================
> [    4.756653] usbcore: registered new interface driver net1080
> [    4.752139] BUG: KCSAN: data-race in mutex_spin_on_owner+0xef/0x1b0

At the very least run your splat through ./scripts/decode_stacktrace.sh

It's impossible to know what the thing is complaining about. I suspect
this is one of those known KCSAN 'bugs' where it can't tell a load+cmp0
is perfectly fine.