* + uml-definitively-kill-subprocesses-on-panic.patch added to -mm tree
@ 2007-10-04 19:31 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2007-10-04 19:31 UTC (permalink / raw)
To: mm-commits; +Cc: ytht.net, jdike
The patch titled
uml: definitively kill subprocesses on panic
has been added to the -mm tree. Its filename is
uml-definitively-kill-subprocesses-on-panic.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: uml: definitively kill subprocesses on panic
From: Lepton Wu <ytht.net@gmail.com>
In a stock 2.6.22.6 kernel, poweroff a user mode linux guest (2.6.22.6 running
in skas0 mode) will halt the host linux. I think the reason is the kernel
thread abort because of a bug. Then the sys_reboot in process of user mode
linux guest is not trapped by the user mode linux kernel and is executed by
host. I think it is better to make sure all of our children process to quit
when user mode linux kernel abort.
[ jdike - the kernel process needs to ignore SIGTERM, plus the waitpid/kill
loop is needed to make sure that all of our children are dead before the
kernel exits ]
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
diff -puN arch/um/os-Linux/skas/process.c~uml-definitively-kill-subprocesses-on-panic arch/um/os-Linux/skas/process.c
--- a/arch/um/os-Linux/skas/process.c~uml-definitively-kill-subprocesses-on-panic
+++ a/arch/um/os-Linux/skas/process.c
@@ -177,7 +177,7 @@ static int userspace_tramp(void *stack)
ptrace(PTRACE_TRACEME, 0, 0, 0);
- init_new_thread_signals();
+ signal(SIGTERM, SIG_DFL);
err = set_interval();
if (err)
panic("userspace_tramp - setting timer failed, errno = %d\n",
diff -puN arch/um/os-Linux/util.c~uml-definitively-kill-subprocesses-on-panic arch/um/os-Linux/util.c
--- a/arch/um/os-Linux/util.c~uml-definitively-kill-subprocesses-on-panic
+++ a/arch/um/os-Linux/util.c
@@ -105,6 +105,44 @@ int setjmp_wrapper(void (*proc)(void *,
void os_dump_core(void)
{
+ int pid;
+
signal(SIGSEGV, SIG_DFL);
+
+ /*
+ * We are about to SIGTERM this entire process group to ensure that
+ * nothing is around to run after the kernel exits. The
+ * kernel wants to abort, not die through SIGTERM, so we
+ * ignore it here.
+ */
+
+ signal(SIGTERM, SIG_IGN);
+ kill(0, SIGTERM);
+ /*
+ * Most of the other processes associated with this UML are
+ * likely sTopped, so give them a SIGCONT so they see the
+ * SIGTERM.
+ */
+ kill(0, SIGCONT);
+
+ /*
+ * Now, having sent signals to everyone but us, make sure they
+ * die by ptrace. Processes can survive what's been done to
+ * them so far - the mechanism I understand is receiving a
+ * SIGSEGV and segfaulting immediately upon return. There is
+ * always a SIGSEGV pending, and (I'm guessing) signals are
+ * processed in numeric order so the SIGTERM (signal 15 vs
+ * SIGSEGV being signal 11) is never handled.
+ *
+ * Run a waitpid loop until we get some kind of error.
+ * Hopefully, it's ECHILD, but there's not a lot we can do if
+ * it's something else. Tell os_kill_ptraced_process not to
+ * wait for the child to report its death because there's
+ * nothing reasonable to do if that fails.
+ */
+
+ while ((pid = waitpid(-1, NULL, WNOHANG)) > 0)
+ os_kill_ptraced_process(pid, 0);
+
abort();
}
_
Patches currently in -mm which might be from ytht.net@gmail.com are
uml-definitively-kill-subprocesses-on-panic.patch
reiserfs-fix-kernel-panic-on-corrupted-directory.patch
reiserfs-workaround-for-dead-loop-in-finish_unfinished.patch
reiserfs-workaround-for-dead-loop-in-finish_unfinished-fix.patch
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2007-10-04 19:31 + uml-definitively-kill-subprocesses-on-panic.patch added to -mm tree akpm
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