From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ivanoab7.miniserver.com ([37.128.132.42] helo=www.kot-begemot.co.uk) by casper.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lHNqP-0020Rv-Lg for linux-um@lists.infradead.org; Wed, 03 Mar 2021 09:31:03 +0000 Subject: Re: linux uml segfault References: <3448a70e7a39b9c3202aeefa7858ace265b8a978.camel@debian.org> <6d37b5aa-36f2-1fce-b70b-8faa0ff882e0@kot-begemot.co.uk>

<529cd4e2f39efffb18125dffab3058aeec3351ce.camel@debian.org> <573e256a-990b-ddf6-7965-367bb8b21229@kot-begemot.co.uk> <1bdedf3c60058e1ae242a2a7f16eee256b0be3e0.camel@debian.org> <6370b92a-84fa-aa21-4270-fcaf1bf42407@kot-begemot.co.uk> <02e348bbb13f0fac92f2147309fb1c006b4583b2.camel@debian.org> <5ee28b97-6111-e12c-d0e9-83a13f2151ce@kot-begemot.co.uk> <5e068447e2067fff8b21c0689f14d080b984f6e0.camel@debian.org> From: Anton Ivanov Message-ID: <3e230682-5bb8-4e86-123d-b157728d489b@kot-begemot.co.uk> Date: Wed, 3 Mar 2021 09:30:56 +0000 MIME-Version: 1.0 In-Reply-To: <5e068447e2067fff8b21c0689f14d080b984f6e0.camel@debian.org> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: rrs@debian.org, Christopher Obbard , "linux-um@lists.infradead.org" Cc: 983379@bugs.debian.org 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 , 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 > "UH\211\345H\201\354", ) at > kernel/panic.c:272 > #7 0x000000006048cca3 in segv (fi=, ip=1615717312, > is_user=0, regs=0x60c2ee58 ) at > arch/um/kernel/trap.c:246 > #8 0x000000006048ce64 in segv_handler (sig=3040981, unused_si=0x6, > regs=0x60c2ee58 ) at arch/um/kernel/trap.c:190 > #9 0x00000000604a2556 in sig_handler_common (sig=11, si=0x60c2fbf0 > , mc=0x60c2fae8 ) 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 > , p=0x0) at arch/um/os-Linux/signal.c:180 > #12 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=, text=, > dev_info=, lflags=, level= out>, facility=) at kernel/printk/printk.c:1932 > #15 vprintk_store (facility=1624806843, level=5, dev_info=0x0, fmt=0x35 > , args=0x1) at > kernel/printk/printk.c:2004 > #16 0x00000000604de8b7 in vprintk_emit (facility=1624806843, > level=1622768673, dev_info=0x35, fmt=0x1 at address 0x1>, args=0x60b97c22) at kernel/printk/printk.c:2029 > #17 0x00000000604debad in vprintk_deferred (fmt=0x1 access memory at address 0x1>, args=0x60b97c21) at > kernel/printk/printk.c:3079 > #18 0x0000000060a554de in printk_deferred (fmt=0x60d895bb > "\n") at kernel/printk/printk.c:3091 > #19 0x000000006092680f in _warn_unseeded_randomness > (previous=, caller=, func_name= out>) at drivers/char/random.c:1534 > #20 _warn_unseeded_randomness (func_name=0x60abf380 <__func__.38> > "get_random_u32", caller=0x608b5f25 , > 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=) at lib/rhashtable.c:203 > #23 0x00000000608b6733 in rhashtable_init (ht=0x60c60e30 > , params=0x608b5e06 ) at > lib/rhashtable.c:1061 > #24 0x000000006080f234 in ipc_init_ids (ids=0x60c60de8 ) > at ipc/util.c:119 > #25 0x0000000060813c6d in sem_init_ns (ns=0x60d895bb ) 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=, > 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=) 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 > , 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 , > 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 > , 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 , > 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 , > args=args@entry=0x7ffe3e7a2260) at dl-error-skeleton.c:227 > #38 0x00007f89909d77b7 in dlerror_run > (operate=operate@entry=0x7f89909d76a0 , > 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=, 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 > , switch_buf=0x60c31e08 ) 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/ _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um