Messages in this thread |  | | | Date | Wed, 07 Jan 2009 21:13:27 -0800 | | From | "Justin P. Mattock" <> | | Subject | Re: [PATCH] stop_machine/cpu hotplug: fix disable_nonboot_cpus |
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Frédéric Weisbecker wrote: > 2009/1/7 Heiko Carstens <heiko.carstens@de.ibm.com>: > >> From: Heiko Carstens <heiko.carstens@de.ibm.com> >> >> disable_nonboot_cpus calls _cpu_down. But _cpu_down requires that the >> caller already created the stop_machine workqueue (like cpu_down does). >> Otherwise a call to stop_machine will lead to accesses to random memory >> regions. >> >> When introducing this new interface (9ea09af3bd3090e8349ca2899ca2011bd94cda85 >> "stop_machine: introduce stop_machine_create/destroy") I missed the second >> call site of _cpu_down. >> So add the missing stop_machine_create/destroy calls to disable_nonboot_cpus >> as well. >> >> Fixes suspend-to-ram/disk and also this bug: >> >> [ 286.547348] BUG: unable to handle kernel paging request at 6b6b6b6b >> [ 286.548940] IP: [<c0150ca4>] __stop_machine+0x88/0xe3 >> [ 286.550598] Oops: 0002 [#1] SMP >> [ 286.560580] Pid: 3273, comm: halt Not tainted (2.6.28-06127-g238c6d5 >> [ 286.560580] EIP: is at __stop_machine+0x88/0xe3 >> [ 286.560580] Process halt (pid: 3273, ti=f1a28000 task=f4530f30 >> [ 286.560580] Call Trace: >> [ 286.560580] [<c03d04e4>] ? _cpu_down+0x10f/0x234 >> [ 286.560580] [<c012a57e>] ? disable_nonboot_cpus+0x58/0xdc >> [ 286.560580] [<c01360c0>] ? kernel_poweroff+0x22/0x39 >> [ 286.560580] [<c0136301>] ? sys_reboot+0xde/0x14c >> [ 286.560580] [<c01331b2>] ? complete_signal+0x179/0x191 >> [ 286.560580] [<c0133396>] ? send_signal+0x1cc/0x1e1 >> [ 286.560580] [<c03de418>] ? _spin_unlock_irqrestore+0x2d/0x3c >> [ 286.560580] [<c0133b65>] ? group_send_signal_info+0x58/0x61 >> [ 286.560580] [<c0133b9e>] ? kill_pid_info+0x30/0x3a >> [ 286.560580] [<c0133d49>] ? sys_kill+0x75/0x13a >> [ 286.560580] [<c01a06cb>] ? mntput_no_expire+ox1f/0x101 >> [ 286.560580] [<c019b3b3>] ? dput+0x1e/0x105 >> [ 286.560580] [<c018ef87>] ? __fput+0x150/0x158 >> [ 286.560580] [<c0157abf>] ? audit_syscall_entry+0x137/0x159 >> [ 286.560580] [<c010329f>] ? sysenter_do_call+0x12/0x34 >> >> Reported-by: "Justin P. Mattock" <justinmattock@gmail.com> >> Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi> >> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> >> --- >> kernel/cpu.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> Index: linux-2.6/kernel/cpu.c >> =================================================================== >> --- linux-2.6.orig/kernel/cpu.c >> +++ linux-2.6/kernel/cpu.c >> @@ -379,8 +379,11 @@ static cpumask_var_t frozen_cpus; >> >> int disable_nonboot_cpus(void) >> { >> - int cpu, first_cpu, error = 0; >> + int cpu, first_cpu, error; >> >> + error = stop_machine_create(); >> + if (error) >> + return error; >> cpu_maps_update_begin(); >> first_cpu = cpumask_first(cpu_online_mask); >> /* We take down all of the non-boot CPUs in one shot to avoid races >> @@ -409,6 +412,7 @@ int disable_nonboot_cpus(void) >> printk(KERN_ERR "Non-boot CPUs are not disabled\n"); >> } >> cpu_maps_update_done(); >> + stop_machine_destroy(); >> return error; >> } >> >> > > > That should explain why suspend to disk failed on my box yesterday on > the processors stage... > Thanks! > > I hate to ask this, but I'm going to anyway: when running gdb /usr/src/linux/vmlinux (hoping to see if gdb will catch the bug); I keep getting: Program terminated with signal SIGKILL, Killed. The program no longer exists. You can't do that without a process to debug.
if i do a: (gdb) disassemble __stop_machine (as described in Documentation); I'll see a bit of info.
How do I start/or figure out a process to debug? i.g. under the bug message that I wrote down, it says Pid: 3273 entering that in (gdb) r 3273 results in a SIGKILL.
regards;
Justin P. Mattock
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