UML - kill subprocesses on exit
PATCH 4/4 UML - kill subprocesses on exit
commit 5161a303c94d812dc854278b58faa1885a669a48
Author: Lepton Wu <[email protected]> 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 ]
--- arch/um/os-Linux/skas/process.c | 2 +- arch/um/os-Linux/util.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-)
arch/um/os-Linux/skas/process.c +1 -1
@@ -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",
arch/um/os-Linux/util.c +38 -0
@@ -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 (); }
-------------------------------------------------------------------------
This SF.net email is sponsored by: Splunk Inc.
Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/
_______________________________________________
User-mode-linux-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
patch uml-kill-subprocesses-on-exit.patch queued to -stable tree
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
Quoted 1 line
From [email protected] Thu Nov 1 12:54:06 2007
From: Lepton Wu <[email protected]>
Date: Thu, 1 Nov 2007 15:53:27 -0400
Subject: UML - kill subprocesses on exit
To: [email protected]
Cc: LKML <[email protected]>, uml-devel <[email protected]>, Lepton Wu <[email protected]>
Message-ID: <[email protected]>
Content-Disposition: inline
From: Lepton Wu <[email protected]>
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 ]
--- arch/um/os-Linux/skas/process.c | 2 +- arch/um/os-Linux/util.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-)
arch/um/os-Linux/skas/process.c +1 -1
@@ -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",
arch/um/os-Linux/util.c +38 -0
@@ -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 [email protected] are
queue-2.6.23/uml-kill-subprocesses-on-exit.patch