==== strace ==== |
[[Code] Steve Work <swork@aventail.com> wrote: > > Coredumps from programs with more than one thread show garbage > information for all threads except the primary. The problem was > introduced with: > > http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=5df240826c90afdc7956f55a004ea6b702df9203 > > on Apr 16 ("fix crash in entry.S restore_all") and is still present in > current builds. |
==== valgrind ==== |
Thanks for working that out. - Hide quoted text - |
> "kill -SEGV" this program and "info threads" the resulting corefile to > see the problem: > > #include <pthread.h> > static void* thread_sleep(void* x) { while (1) sleep(30); } > int main(int c, char** v) { > const static int tcount = 5; > pthread_t thr[tcount]; > int i; > for (i=0; i<tcount; ++i) > pthread_create(&thr[i], NULL, thread_sleep, NULL); > while (1) > sleep(30); > return 0; > } > > (gdb) info threads > 7 process 18138 0x00000246 in ?? () > 6 process 18139 0x00000246 in ?? () > 5 process 18140 0x00000246 in ?? () > 4 process 18141 0x00000246 in ?? () > 3 process 18142 0x00000246 in ?? () > 2 process 18143 0x00000246 in ?? () > * 1 process 18137 0xb7e69db6 in nanosleep () from /lib/tls/libc.so.6 > (gdb) > > All these threads should show a legitimate location (the same spot in > nanosleep) and do on kernels prior to the commit named above. (Notice > one too many threads listed here also -- is this a related problem?) > > Commenting out this line (in asm/i386/kernel/process.c:copy_thread) > fixes the corefiles: > > childregs = (struct pt_regs *) ((unsigned long) childregs - 8); > > but presumably re-introduces the crash the original patch was intended > to fix. Should this line be conditioned somehow? Or do the corefile > write routines need to know about this adjusted offset? > Yes, I guess fixing up the core output would be the way to fix it. ] |
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