On 02/03/2021 17:27, Ritesh Raj Sarraf wrote:
On Tue, 2021-03-02 at 17:05 +0000, Anton Ivanov wrote:
So the best I can extract for you is to compile the kernel with as
much
information as possible.
Can you try using one of the older kernels so we can verify if this
is indeed a 5.10 thing.
That was the first thing I tried. I tested it with 5.10, 5.9 and 5.4.
All 3 crashed. That's when I knew this one was going to be painful one
to conclude.
The only other input I have is that I have one more user who's reported
to be able to reproduce the issue.
OTOH, I have one more user (other than you) who's not been able to
reproduce the issue.
I will do a dissect the moment I figure out how to reproduce it. I
will try to do some more experiments on that tomorrow.
I tried to alter the userspace a bit, but it makes no difference.
Out of curiosity, what are you running it on?
Meanwhile, I enabled some debug info in the kernel. Here's what I have
got so far:
```
(gdb) bt
#0 0x00007f89908dc087 in kill () at ../sysdeps/unix/syscall-
template.S:120
#1 0x00000000604a3514 in uml_abort () at arch/um/os-Linux/util.c:94
#2 0x00000000604a3791 in os_dump_core () at arch/um/os-
Linux/util.c:149
#3 0x000000006048d126 in panic_exit (self=0x2e66d5, unused1=6,
unused2=0x0) at arch/um/kernel/um_arch.c:217
#4 0x00000000604c725a in notifier_call_chain (nl=0x2e66d5, val=0,
v=0x60d82f40 <buf>, nr_to_call=-1, nr_calls=0x0) at
kernel/notifier.c:83
#5 0x00000000604c72f6 in atomic_notifier_call_chain (nh=0x2e66d5,
val=6, v=0x0) at kernel/notifier.c:217
#6 0x0000000060a54607 in panic (fmt=0x60a55225 <printk>
"UH\211\345H\201\354", <incomplete sequence \320>) at
kernel/panic.c:272
#7 0x000000006048cca3 in segv (fi=<incomplete type>, ip=1615717312,
is_user=0, regs=0x60c2ee58 <cpu0_irqstack+11864>) at
arch/um/kernel/trap.c:246
#8 0x000000006048ce64 in segv_handler (sig=3040981, unused_si=0x6,
regs=0x60c2ee58 <cpu0_irqstack+11864>) at arch/um/kernel/trap.c:190
#9 0x00000000604a2556 in sig_handler_common (sig=11, si=0x60c2fbf0
<cpu0_irqstack+15344>, mc=0x60c2fae8 <cpu0_irqstack+15080>) at
arch/um/os-Linux/signal.c:48
#10 0x00000000604a2aa2 in sig_handler (sig=3040981, si=0x6, mc=0x0) at
arch/um/os-Linux/signal.c:81
#11 0x00000000604a265f in hard_handler (sig=3040981, si=0x60c2fbf0
<cpu0_irqstack+15344>, p=0x0) at arch/um/os-Linux/signal.c:180
#12 <signal handler called>
The code here is:
static inline u32 printk_caller_id(void)
{
return in_task() ? task_pid_nr(current) :
0x80000000 + raw_smp_processor_id();
}
That is something which should not bomb out unless we have memory corruption or
something along those lines - current being invalid.
A.
#13 0x00000000604de3c0 in printk_caller_id () at
kernel/printk/printk.c:1924
#14 log_output (text_len=<optimized out>, text=<optimized out>,
dev_info=<optimized out>, lflags=<optimized out>, level=<optimized
out>, facility=<optimized out>) at kernel/printk/printk.c:1932
#15 vprintk_store (facility=1624806843, level=5, dev_info=0x0, fmt=0x35
<error: Cannot access memory at address 0x35>, args=0x1) at
kernel/printk/printk.c:2004
#16 0x00000000604de8b7 in vprintk_emit (facility=1624806843,
level=1622768673, dev_info=0x35, fmt=0x1 <error: Cannot access memory
at address 0x1>, args=0x60b97c22) at kernel/printk/printk.c:2029
#17 0x00000000604debad in vprintk_deferred (fmt=0x1 <error: Cannot
access memory at address 0x1>, args=0x60b97c21) at
kernel/printk/printk.c:3079
#18 0x0000000060a554de in printk_deferred (fmt=0x60d895bb <textbuf+91>
"\n") at kernel/printk/printk.c:3091
#19 0x000000006092680f in _warn_unseeded_randomness
(previous=<optimized out>, caller=<optimized out>, func_name=<optimized
out>) at drivers/char/random.c:1534
#20 _warn_unseeded_randomness (func_name=0x60abf380 <__func__.38>
"get_random_u32", caller=0x608b5f25 <bucket_table_alloc+287>,
previous=0x35) at drivers/char/random.c:1516
#21 0x0000000060927d47 in get_random_u32 () at
drivers/char/random.c:2221
#22 0x00000000608b5f25 in bucket_table_alloc (nbuckets=64, gfp=3264,
ht=<optimized out>) at lib/rhashtable.c:203
#23 0x00000000608b6733 in rhashtable_init (ht=0x60c60e30
<init_ipc_ns+80>, params=0x608b5e06 <bucket_table_alloc>) at
lib/rhashtable.c:1061
#24 0x000000006080f234 in ipc_init_ids (ids=0x60c60de8 <init_ipc_ns+8>)
at ipc/util.c:119
#25 0x0000000060813c6d in sem_init_ns (ns=0x60d895bb <textbuf+91>) at
ipc/sem.c:254
#26 0x0000000060015b5d in sem_init () at ipc/sem.c:268
#27 0x00007f89906d92f7 in ?? () from /lib/x86_64-linux-
gnu/libcom_err.so.2
#28 0x00007f8990ab8fb2 in call_init (l=<optimized out>,
argc=argc@entry=5, argv=argv@entry=0x7ffe3e7a4c98,
env=env@entry=0x7ffe3e7a4cc8) at dl-init.c:72
#29 0x00007f8990ab90b9 in call_init (env=0x7ffe3e7a4cc8,
argv=0x7ffe3e7a4c98, argc=5, l=<optimized out>) at dl-init.c:30
#30 _dl_init (main_map=0x61497ea0, argc=5, argv=0x7ffe3e7a4c98,
env=0x7ffe3e7a4cc8) at dl-init.c:119
#31 0x00007f89909d82bd in __GI__dl_catch_exception
(exception=exception@entry=0x0, operate=operate@entry=0x7f8990abc5a0
<call_dl_init>, args=args@entry=0x7ffe3e7a1e80) at dl-error-
skeleton.c:182
#32 0x00007f8990abd028 in dl_open_worker (a=a@entry=0x7ffe3e7a2020) at
dl-open.c:758
#33 0x00007f89909d8260 in __GI__dl_catch_exception
(exception=exception@entry=0x7ffe3e7a2000,
operate=operate@entry=0x7f8990abcc70 <dl_open_worker>,
args=args@entry=0x7ffe3e7a2020) at dl-error-skeleton.c:208
#34 0x00007f8990abc8ca in _dl_open (file=0x7ffe3e7a22a0
"libnss_nis.so.2", mode=-2147483646, caller_dlopen=0x7f89909bf3a6
<nss_load_library+294>, nsid=-2, argc=5, argv=0x7ffe3e7a2000,
env=0x7ffe3e7a4cc8)
at dl-open.c:837
#35 0x00007f89909d76dd in do_dlopen (ptr=ptr@entry=0x7ffe3e7a2260) at
dl-libc.c:96
#36 0x00007f89909d8260 in __GI__dl_catch_exception
(exception=exception@entry=0x7ffe3e7a21e0,
operate=operate@entry=0x7f89909d76a0 <do_dlopen>,
args=args@entry=0x7ffe3e7a2260) at dl-error-skeleton.c:208
#37 0x00007f89909d831f in __GI__dl_catch_error
(objname=objname@entry=0x7ffe3e7a2238,
errstring=errstring@entry=0x7ffe3e7a2240,
mallocedp=mallocedp@entry=0x7ffe3e7a2237,
operate=operate@entry=0x7f89909d76a0 <do_dlopen>,
args=args@entry=0x7ffe3e7a2260) at dl-error-skeleton.c:227
#38 0x00007f89909d77b7 in dlerror_run
(operate=operate@entry=0x7f89909d76a0 <do_dlopen>,
args=args@entry=0x7ffe3e7a2260) at dl-libc.c:46
#39 0x00007f89909d7846 in __GI___libc_dlopen_mode
(name=name@entry=0x7ffe3e7a22a0 "libnss_nis.so.2", mode=mode@entry=-
2147483646) at dl-libc.c:195
#40 0x00007f89909bf3a6 in nss_load_library (ni=ni@entry=0x61497db0) at
nsswitch.c:359
#41 0x00007f89909bfc39 in __GI___nss_lookup_function (ni=0x61497db0,
fct_name=<optimized out>, fct_name@entry=0x7f899089b020 "setgrent") at
nsswitch.c:467
#42 0x00007f899089554b in init_nss_interface () at nss_compat/compat-
grp.c:83
#43 init_nss_interface () at nss_compat/compat-grp.c:79
#44 0x00007f8990895e35 in _nss_compat_getgrnam_r (name=0x7f8990a2a1e0
"tty", grp=0x7ffe3e7a2910, buffer=0x7ffe3e7a24e0 "", buflen=1024,
errnop=0x7f899089eb00) at nss_compat/compat-grp.c:486
#45 0x00007f8990968b85 in __getgrnam_r (name=name@entry=0x7f8990a2a1e0
"tty", resbuf=resbuf@entry=0x7ffe3e7a2910,
buffer=buffer@entry=0x7ffe3e7a24e0 "", buflen=1024,
result=result@entry=0x7ffe3e7a2908)
at ../nss/getXXbyYY_r.c:315
#46 0x00007f89909d6b77 in grantpt (fd=fd@entry=5) at
../sysdeps/unix/grantpt.c:152
#47 0x00007f8990a9394e in __GI_openpty (amaster=0x60c2bd94,
aslave=0x60c2bd98, name=0x0, termp=0x0, winp=0x0) at openpty.c:103
#48 0x00000000604a1f65 in openpty_cb (arg=0x60c2bd94) at arch/um/os-
Linux/sigio.c:407
#49 0x00000000604a58d0 in start_idle_thread (stack=0x60c28000
<init_thread_info>, switch_buf=0x60c31e08 <init_task+4936>) at
arch/um/os-Linux/skas/process.c:598
#50 0x0000000060004a3d in start_uml () at
arch/um/kernel/skas/process.c:45
#51 0x00000000600047b2 in linux_main (argc=1624806843, argv=0x40709000)
at arch/um/kernel/um_arch.c:334
#52 0x000000006000574f in main (argc=5, argv=0x7ffe3e7a4c98, envp=0x35)
at arch/um/os-Linux/main.c:144
(gdb)
```
--
Anton R. Ivanov
https://www.kot-begemot.co.uk/
