Bug 248811

Summary: panic: deadlres_td_sleep_q: possible deadlock detected
Product: Base System Reporter: Masachika ISHIZUKA <ish>
Component: kernAssignee: freebsd-bugs (Nobody) <bugs>
Status: Open ---    
Severity: Affects Only Me CC: cy, grahamperrin, ish
Priority: --- Keywords: crash
Version: CURRENT   
Hardware: Any   
OS: Any   
Attachments:
Description Flags
/var/crash/info.8(r363950M)
none
/var/crash/info.9(r364441M)
none
/var/crash/core.txt.8(r363950M)
none
/var/crash/core.txt.9(r364441M) none

Description Masachika ISHIZUKA 2020-08-21 16:44:25 UTC 
Created attachment 217422 [details]
/var/crash/info.8(r363950M)

Hi.

I'm using 13.0-CURRENT r364441M on Dell XPS12 9Q33.
(I'm using udf2 patched r364441.)
This machine was panicked with the following messages.

panic: deadlres_td_sleep_q: possible deadlock detected for 0xfffffe006408be00 (find), blocked for 1802043 ticks

Yesterday, I was using r363950M and the same panic has occured.

Vmcore was uploaded to the below.
https://www.ish.org/files/vmcore.8.r363950M.xz
https://www.ish.org/files/vmcore.9.r364441M.xz
Comment 1 Masachika ISHIZUKA 2020-08-21 16:46:22 UTC 
Created attachment 217424 [details]
/var/crash/info.9(r364441M)
Comment 2 Masachika ISHIZUKA 2020-08-21 16:47:06 UTC 
Created attachment 217425 [details]
/var/crash/core.txt.8(r363950M)
Comment 3 Masachika ISHIZUKA 2020-08-21 16:47:49 UTC 
Created attachment 217426 [details]
/var/crash/core.txt.9(r364441M)
Comment 4 Conrad Meyer freebsd_committer freebsd_triage 2020-08-21 17:23:11 UTC 
Looking at core.txt.8:

These prints are not the problem, but it would be nice to fix the drm driver not to do lock asserts during panic:

WARNING !drm_modeset_is_locked(&plane->mutex) failed at /usr/local/sys/modules/drm-current-kmod/drivers/gpu/drm/drm_atomic_helper.c:821
#0 0xffffffff82ebb673 at linux_dump_stack+0x23

It's a shame deadlkres doesn't do something like print_lockchain().  That'd help diagnose these things.

ps shows the only find process is blocked on nfs:

    0 61433 61429 0  52  0   18540   5752 nfs      D     -      0:13.33 [find]

There are several nfscl threads sleeping on nfscl, which indicates renewthread, i.e., probably we're waiting on a server that went away.  I'd guess that's what find is also waiting on.
Comment 5 Conrad Meyer freebsd_committer freebsd_triage 2020-08-21 17:24:25 UTC 
core.txt.9 shows the same.
Comment 6 Graham Perrin freebsd_committer freebsd_triage 2023-06-11 09:50:36 UTC 
How might we refine the summary line here? 

To distinguish this report from: 

* bug 243876
* bug 257291
* bug 264233
* bug 271945.