* [PATCH 4/4] UML - kill subprocesses on exit
@ 2007-11-01 19:53 Jeff Dike
2007-11-14 18:58 ` patch uml-kill-subprocesses-on-exit.patch queued to -stable tree gregkh
0 siblings, 1 reply; 2+ messages in thread
From: Jeff Dike @ 2007-11-01 19:53 UTC (permalink / raw)
To: stable; +Cc: LKML, uml-devel, Lepton Wu
commit 5161a303c94d812dc854278b58faa1885a669a48
Author: Lepton Wu <ytht.net@gmail.com>
Date: Tue Oct 16 01:27:35 2007 -0700
uml: definitively kill subprocesses on panic
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/um/os-Linux/skas/process.c | 2 +-
arch/um/os-Linux/util.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index ba9af8d..607d2b8 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -182,7 +182,7 @@ static int userspace_tramp(void *stack)
ptrace(PTRACE_TRACEME, 0, 0, 0);
- init_new_thread_signals();
+ signal(SIGTERM, SIG_DFL);
err = set_interval(1);
if(err)
panic("userspace_tramp - setting timer failed, errno = %d\n",
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 7cbcf48..ef09543 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -105,6 +105,44 @@ int setjmp_wrapper(void (*proc)(void *, 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();
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
* patch uml-kill-subprocesses-on-exit.patch queued to -stable tree
2007-11-01 19:53 [PATCH 4/4] UML - kill subprocesses on exit Jeff Dike
@ 2007-11-14 18:58 ` gregkh
0 siblings, 0 replies; 2+ messages in thread
From: gregkh @ 2007-11-14 18:58 UTC (permalink / raw)
To: ytht.net, akpm, gregkh, jdike, linux-kernel, torvalds,
user-mode-linux-devel
Cc: stable, stable-commits
This is a note to let you know that we have just queued up the patch titled
Subject: UML - kill subprocesses on exit
to the 2.6.23-stable tree. Its filename is
uml-kill-subprocesses-on-exit.patch
A git repo of this tree can be found at
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>From stable-bounces@linux.kernel.org Thu Nov 1 12:54:06 2007
From: Lepton Wu <ytht.net@gmail.com>
Date: Thu, 1 Nov 2007 15:53:27 -0400
Subject: UML - kill subprocesses on exit
To: stable@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>, uml-devel <user-mode-linux-devel@lists.sourceforge.net>, Lepton Wu <ytht.net@gmail.com>
Message-ID: <20071101195327.GA8882@c2.user-mode-linux.org>
Content-Disposition: inline
From: Lepton Wu <ytht.net@gmail.com>
commit a24864a1d52a97e345a6bd4862a057f98364d098
uml: definitively kill subprocesses on panic
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
arch/um/os-Linux/skas/process.c | 2 +-
arch/um/os-Linux/util.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 1 deletion(-)
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -182,7 +182,7 @@ static int userspace_tramp(void *stack)
ptrace(PTRACE_TRACEME, 0, 0, 0);
- init_new_thread_signals();
+ signal(SIGTERM, SIG_DFL);
err = set_interval(1);
if(err)
panic("userspace_tramp - setting timer failed, errno = %d\n",
--- a/arch/um/os-Linux/util.c
+++ b/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 stable-queue which might be from ytht.net@gmail.com are
queue-2.6.23/uml-kill-subprocesses-on-exit.patch
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