Re: Futex crash in Normal 4.9 Kernel

Re: Futex crash in Normal 4.9 Kernel

[Greg KH]

On Mon, Aug 09, 2021 at 04:44:13PM +0530, nelakurthi koteswararao wrote:
> Dear Stable kernel Contributors
> 
> Observed Futex kernel crash while using navigation app in Broxton Device
> flashed with Normal 4.9.x kernel.
> Futex Crash details are given below.
> {{
> 1>[ 1383.591633] Time of kernel crash: (2021-02-16 12:04:19)
> <1>[ 1383.597480] BUG: unable to handle kernel NULL pointer dereference at
>           (null)
> <1>[ 1383.606247] IP: [<ffffffffa211c271>] futex_wake+0xe1/0x180
> <4>[ 1383.612386] PGD 130f62067
> <4>[ 1383.615209] PUD 130f61067
> <4>[ 1383.618230] PMD 0
> <4>[ 1383.620275]
> <4>[ 1383.621926] Oops: 0000 [#1] PREEMPT SMP
> <4>[ 1383.626211] Modules linked in: bcmdhd(O) sxmio(C) rfkill_gpio
> cfg80211 ehset dwc3_pci dwc3 ishtp_tty_client dabridge camera_status mei_me
> anc_ipc igb_avb(O) mei xhci_pci xhci_hcd intel_ish_ipc intel_ishtp
> snd_soc_bxt_ivi_ull trusty_timer trusty_wall trusty_log trusty_virtio
> trusty_ipc dcsd_ts trusty_mem cyttsp6_i2c snd_soc_skl trusty
> snd_soc_skl_ipc snd_soc_sst_ipc cyttsp6_device_access snd_soc_sst_dsp
> snd_soc_sst_acpi virtio_ring snd_soc_sst_match snd_hda_ext_core
> cyttsp6_debug snd_hda_core dcsd_display virtio cyttsp6 [last unloaded:
> bcmdhd]
> <4>[ 1383.680139] CPU: 2 PID: 7292 Comm: Thread-48 Tainted: G     U   C O
>  4.9.232-quilt-2e5dc0ac-g33302ae #1

4.9.232 is quite old, it was released over a year ago.  A large number
of futexes fixes has gone in since then, can you please update to the
latest 4.9.y release (4.9.279 as of today) and let us know if that
solves the issue or not?

thanks,

greg k-h

Re: Futex crash in Normal 4.9 Kernel

[Greg KH]

On Mon, Aug 09, 2021 at 05:52:17PM +0530, nelakurthi koteswararao wrote:
> Dear Greg,
> 
> Thank you for your reply. I noticed most of the futex changes between
> 4.9.233 to 4.9.279 is related to Priority Inheritance that comes in
> to use in the Real time kernel. But I am using the 4.9.232 Normal Kernel.

I do not know what a "4.9.232 Normal Kernel" is.

> That's the reason I posted futex crash to the mailing list for input.
> is the race between futex_wait() thread and futex_wake() threads leading to
> NULL pointer crash? any input in that direction?

Again, please try the latest 4.9.y kernel release, we do not support
older releases for obvious reasons.

thanks,

greg k-h