Re: [Crash-utility] Crash in crash

Hi Your patch works but I get a "strange" error message: please wait... (determining panic task) bt: bsearch for tgid failed: task: ffffffc01cfed400 tgid: 5040 KERNEL: vmlinux DUMPFILE: vmcore .... This message does not occur with my patch. Jan

Jan Karlsson Senior Software Engineer System Assurance Sony Mobile Communications Tel: +46 703 062 174 jan.karlsson(a)sonymobile.com sonymobile.com -----Original Message----- From: crash-utility-bounces(a)redhat.com [mailto:crash-utility-bounces@redhat.com] On Behalf Of Dave Anderson Sent: den 21 oktober 2014 16:32 To: Discussion list for crash utility usage, maintenance and development Subject: Re: [Crash-utility] Crash in crash Hi Jan, Good catch. As far as a fix goes, it would be more efficient if tgid_quick_search() just returns a NULL in that case. Try the attached patch. Thanks, Dave ----- Original Message ----- > > > Hi Dave > > > > I have a vmcore file for ARM64 that crashes Crash during startup. > The core file is created at a hardware watchdog (I believe) so there > is no panic message or something similar in the log. > > > > This is the printout from Crash running under gdb, after the > copyrights and config information: > > > > please wait... (determining panic task) > > Program received signal SIGSEGV, Segmentation fault. > > 0x000000000047ed40 in tgid_quick_search (tgid=5040) at memory.c:4114 > > 4114 if (tgid == last->tgid) { > > > > (gdb) bt > > #0 0x000000000047ed40 in tgid_quick_search (tgid=5040) at > memory.c:4114 > > #1 0x000000000047f046 in get_task_mem_usage > (task=18446743799318107136, > tm=0x7fffffff6f40) > > at memory.c:4186 > > #2 0x000000000047c679 in vm_area_dump (task=18446743799318107136, > flag=10, vaddr=0, ref=0x0) > > at memory.c:3671 > > #3 0x000000000047ec08 in in_user_stack (task=18446743799318107136, > vaddr=0) at memory.c:4063 > > #4 0x00000000004fd9fe in arm64_get_dumpfile_stackframe > (frame=<synthetic > pointer>, > > bt=<optimized out>) at arm64.c:1077 > > #5 arm64_get_stack_frame (bt=0x7fffffffc690, pcp=0x7fffffff9560, > spp=0x7fffffff9568) > > at arm64.c:1103 > > #6 0x00000000004de409 in back_trace (bt=0x7fffffffc690) at > kernel.c:2533 > > #7 0x00000000004d1563 in foreach (fd=0x7fffffffc7c0) at task.c:6161 > > #8 0x00000000004d2bbd in panic_search () at task.c:6425 > > #9 0x00000000004d4454 in get_panic_context () at task.c:5364 > > #10 task_init () at task.c:491 > > #11 0x000000000046146e in main_loop () at main.c:801 > > #12 0x00000000006467a3 in captured_command_loop (data=<optimized > out>) at > main.c:258 > > #13 0x000000000064535b in catch_errors (func=0x646790 > <captured_command_loop>, func_args=0x0, > > errstring=0x873235 "", mask=6) at exceptions.c:557 > > #14 0x0000000000647726 in captured_main (data=<optimized out>) at > main.c:1064 > > #15 0x000000000064535b in catch_errors (func=0x646aa0 > <captured_main>, func_args=0x7fffffffe030, > > errstring=0x873235 "", mask=6) at exceptions.c:557 > > #16 0x0000000000647a84 in gdb_main (args=<optimized out>) at > main.c:1079 > > #17 0x0000000000647abe in gdb_main_entry (argc=<optimized out>, > argv=<optimized out>) > > at main.c:1099 > > #18 0x000000000045f61f in main (argc=3, argv=0x7fffffffe188) at > main.c:758 > > > > (gdb) p tt->last_tgid > > $1 = (struct tgid_context *) 0x0 > > > > Source code for tgid_quick_search: > > static struct tgid_context * > > tgid_quick_search(ulong tgid) > > { > > struct tgid_context *last, *next; > > > > tt->tgid_searches++; > > > > last = tt->last_tgid; > > if (tgid == last->tgid) { > > tt->tgid_cache_hits++; > > return last; > > } > > .... > > } > > > > So 'last' becomes 0 which causes the crash. > > > > After some more investigation I have seen that "tt->last_tgid" is > initialized in function sort_tgid_array in task.c, but that function > seems to be called at a later stage. > > > > By adding a line in tgid_quick_search: > > > > static struct tgid_context * > > tgid_quick_search(ulong tgid) > > { > > struct tgid_context *last, *next; > > > > tt->tgid_searches++; > > > > if (tt->last_tgid == 0) sort_tgid_array(); // added line > > last = tt->last_tgid; > > if (tgid == last->tgid) { > > tt->tgid_cache_hits++; > > return last; > > } > > ... > > > > I can run Crash on this core file. However I do not know if this is > the best way to fix the problem. > > > > Jan > > > > Jan Karlsson > > Senior Software Engineer > > System Assurance > > > > Sony Mobile Communications > > Tel: +46 703 062 174 > > jan.karlsson(a)sonymobile.com > > > > sonymobile.com > > > > > > > > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility