Oleg Nesterov
377d75dafa
wait: WSTOPPED|WCONTINUED hangs if a zombie child is traced by real_parent ...
"A zombie is only visible to its ptracer" logic in wait_consider_task()
is very wrong. Trivial test-case:
#include <unistd.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
int main(void)
{
int child = fork();
if (!child) {
assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0);
return 0x23;
}
assert(waitid(P_ALL, child, NULL, WEXITED | WNOWAIT) == 0);
assert(waitid(P_ALL, 0, NULL, WSTOPPED) == -1);
return 0;
}
it hangs in waitpid(WSTOPPED) despite the fact it has a single zombie
child. This is because wait_consider_task(ptrace => 0) sees p->ptrace and
cleares ->notask_error assuming that the debugger should detach and notify
us.
Change wait_consider_task(ptrace => 0) to pretend that ptrace == T if the
child is traced by us. This really simplifies the logic and allows us to
do more fixes, see the next changes. This also hides the unwanted group
stop state automatically, we can remove another ptrace_reparented() check.
Unfortunately, this adds the following behavioural changes:
1. Before this patch wait(WEXITED | __WNOTHREAD) does not reap
a natural child if it is traced by the caller's sub-thread.
Hopefully nobody will ever notice this change, and I think
that nobody should rely on this behaviour anyway.
2. SIGNAL_STOP_CONTINUED is no longer hidden from debugger if
it is real parent.
While this change comes as a side effect, I think it is good
by itself. The group continued state can not be consumed by
another process in this case, it doesn't depend on ptrace,
it doesn't make sense to hide it from real parent.
Perhaps we should add the thread_group_leader() check before
wait_task_continued()? May be, but this shouldn't depend on
ptrace_reparented().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Lennart Poettering <lpoetter@redhat.com>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:06 -07:00
mm: per-thread vma caching
2014-04-07 16:35:53 -07:00
Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm
2014-04-05 13:20:43 -07:00
gcov: reuse kbasename helper
2013-11-13 12:09:34 +09:00
genirq: Export symbol no_action()
2014-03-22 11:33:09 +01:00
Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-03-31 14:13:25 -07:00
Merge branches 'pm-runtime' and 'pm-sleep'
2014-03-20 13:25:54 +01:00
printk: fix one circular lockdep warning about console_lock
2014-04-03 16:21:08 -07:00
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-03-31 11:21:19 -07:00
Merge branch 'akpm' (incoming from Andrew)
2014-04-03 16:22:16 -07:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-04-01 11:00:07 -07:00
Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm
2014-04-05 13:20:43 -07:00
Ignore generated file kernel/x509_certificate_list
2013-12-10 18:21:34 +00:00
AUDIT: Allow login in non-init namespaces
2014-03-30 17:02:53 -07:00
audit: Use struct net not pid_t to remember the network namespce to reply in
2014-02-28 04:04:33 -08:00
inotify: Fix reporting of cookies for inotify events
2014-02-18 11:17:17 +01:00
inotify: Fix reporting of cookies for inotify events
2014-02-18 11:17:17 +01:00
audit: Update kdoc for audit_send_reply and audit_list_rules_send
2014-03-08 15:31:54 -08:00
execve: use 'struct filename *' for executable name passing
2014-02-05 12:54:53 -08:00
mm: do not allocate page->ptl dynamically, if spinlock_t fits to long
2013-12-20 12:25:45 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2014-04-03 09:26:18 -07:00
Merge branch 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2014-04-03 13:05:42 -07:00
cgroup: drop const from @buffer of cftype->write_string()
2014-03-19 10:23:54 -04:00
Merge branch 'x86-x32-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-04-02 12:51:41 -07:00
context_tracking: Wrap static key check into more intuitive function name
2013-12-02 20:43:14 +01:00
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2013-11-14 16:55:11 +09:00
Merge branch 'akpm' (incoming from Andrew)
2014-04-03 16:22:16 -07:00
wait: WSTOPPED|WCONTINUED hangs if a zombie child is traced by real_parent
2014-04-07 16:36:06 -07:00
asmlinkage: Make main_extable_sort_needed visible
2014-02-13 18:13:22 -08:00
mm, mempolicy: remove per-process flag
2014-04-07 16:35:54 -07:00
libata, freezer: avoid block device removal while system is frozen
2013-12-19 13:50:32 -05:00
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-03-31 10:59:39 -07:00
compat: Get rid of (get|put)_compat_time(val|spec)
2014-02-02 14:09:12 -08:00
kernel/groups.c: remove return value of set_groups
2014-04-03 16:21:05 -07:00
timer: Remove code redundancy while calling get_nohz_timer_target()
2014-03-20 12:35:46 +01:00
kernel: audit/fix non-modular users of module_init in core code
2014-04-03 16:21:07 -07:00
perf/x86: Warn to early_printk() in case irq_work is too slow
2014-02-21 21:49:07 +01:00
kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS
2013-11-15 09:32:22 +09:00
kernel: audit/fix non-modular users of module_init in core code
2014-04-03 16:21:07 -07:00
execve: use 'struct filename *' for executable name passing
2014-02-05 12:54:53 -08:00
kprobes: use KSYM_NAME_LEN to size identifier buffers
2013-11-13 12:09:26 +09:00
rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c
2014-02-26 06:35:16 -08:00
kthread: ensure locality of task_struct allocations
2014-04-03 16:20:49 -07:00
Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-03-31 14:13:25 -07:00
Nothing major: the stricter permissions checking for sysfs broke
2014-04-06 09:38:07 -07:00
notifier: Substitute rcu_access_pointer() for rcu_dereference_raw()
2014-02-26 06:35:13 -08:00
padata: Fix wrong usage of rcu_dereference()
2013-12-05 21:28:42 +08:00
Nothing major: the stricter permissions checking for sysfs broke
2014-04-06 09:38:07 -07:00
params: improve standard definitions
2013-12-04 14:09:46 +10:30
pid_namespace: pidns_get() should check task_active_pid_ns() != NULL
2014-04-02 16:20:21 -07:00
posix-timers: Convert abuses of BUG_ON to WARN_ON
2013-12-09 16:56:29 +01:00
kernel: audit/fix non-modular users of module_init in core code
2014-04-03 16:21:07 -07:00
kernel/compat: convert to COMPAT_SYSCALL_DEFINE
2014-03-06 15:35:10 +01:00
kexec: migrate to reboot cpu
2013-12-18 19:04:50 -08:00
treewide: Fix typo in Documentation/DocBook
2014-02-19 14:58:17 +01:00
res_counter: remove interface for locked charging and uncharging
2014-04-07 16:35:54 -07:00
kernel/resource.c: make reallocate_resource() static
2014-04-03 16:21:07 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2014-04-03 09:26:18 -07:00
Merge branch 'master' into for-next
2014-02-20 14:54:28 +01:00
smp: Rename __smp_call_function_single() to smp_call_function_single_async()
2014-02-24 14:47:15 -08:00
softirq: Add linux/irq.h to make it compile again
2014-03-19 11:28:14 +01:00
stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()
2014-03-11 11:33:47 +01:00
mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE
2014-04-07 16:35:52 -07:00
fs, kernel: permit disabling the uselib syscall
2014-04-03 16:21:05 -07:00
drop_caches: add some documentation and info message
2014-04-03 16:21:04 -07:00
kernel/sysctl_binary.c: use scnprintf() instead of snprintf()
2013-11-13 12:09:33 +09:00
KEYS: correct alignment of system_certificate_list content in assembly file
2013-12-10 18:25:28 +00:00
KEYS: correct alignment of system_certificate_list content in assembly file
2013-12-10 18:25:28 +00:00
genetlink: only pass array to genl_register_family_with_ops()
2013-11-19 16:39:05 -05:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-04-01 11:00:07 -07:00
rcutorture: Gracefully handle NULL cleanup hooks
2014-02-23 09:04:39 -08:00
Nothing major: the stricter permissions checking for sysfs broke
2014-04-06 09:38:07 -07:00
smp: Rename __smp_call_function_single() to smp_call_function_single_async()
2014-02-24 14:47:15 -08:00
kernel: audit/fix non-modular users of module_init in core code
2014-04-03 16:21:07 -07:00
kernel: audit/fix non-modular users of module_init in core code
2014-04-03 16:21:07 -07:00
kernel/watchdog.c: touch_nmi_watchdog should only touch local cpu not every one
2014-04-03 16:20:58 -07:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2014-04-01 11:00:07 -07:00
377d75dafa