Re: zombie with CLONE_THREAD
From: Andreas Schwab (schwab_at_suse.de)
Date: 06/30/04
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- In reply to: Roland McGrath: "Re: zombie with CLONE_THREAD"
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To: Roland McGrath <roland@redhat.com> Date: Wed, 30 Jun 2004 11:04:46 +0200
Roland McGrath <roland@redhat.com> writes:
> Are you saying that if the ptracer dies, it can leave some threads in limbo?
> I think that case is supposed to work because forget_original_parent will
> move all the threads ptrace'd by the dying tracer process to be ptrace'd by
> init, which will then clean up their zombies as previously described.
Here is the test case, run it with "strace -f ./clone". When the bug
happens then strace is stuck waiting for it's traced child that just died,
but you may have to try a few times before it happens.
#include <stdio.h>
#include <signal.h>
#include <sched.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
extern int __clone (int (*__fn) (void *__arg), void *__child_stack,
int __flags, void *__arg, ...);
extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
size_t __child_stack_size, int __flags, void *__arg, ...);
static int thread (void *arg)
{
write (2, "thread\n", sizeof ("thread\n"));
*(volatile int *) 0;
return 0;
}
#define STACK_SIZE 1024 * 1024
#define CLONE_FLAGS CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM
int
main (void)
{
void *stack = mmap (0, STACK_SIZE, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0);
pid_t pid;
#ifdef __ia64__
pid = __clone2 (thread, stack, STACK_SIZE - 64, CLONE_FLAGS, 0);
#else
pid = __clone (thread, stack + STACK_SIZE - 64, CLONE_FLAGS, 0);
#endif
printf ("pid = %d\n", pid);
sleep (1);
return 0;
}
Andreas.
-- Andreas Schwab, SuSE Labs, schwab@suse.de SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
- Previous message: Vojtech Pavlik: "Re: Continue: psmouse.c - synaptics touchpad driver sync problem"
- In reply to: Roland McGrath: "Re: zombie with CLONE_THREAD"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
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