7:27 a.m.
----- "Chandru" <chandru(a)in.ibm.com> wrote:
Hi Dave,
Thanks a lot for catching the segfault issue and finding the root cause for it. Here
follows the updated patch taking in the suggestions from the review comments.
kdump installs NT_PRSTATUS notes into vmcore file only to the cpus that were
online at the time of crash. In such cases, while reading in the notes from the
dump file, we are unsure of the cpu to NT_PRSTATUS mapping. The cpu
possible, present and online map is not available until cpu_maps_init() initializes
them. Hence we remap the prstatus pointer array to online cpus just after
a call to this function.
Signed-off-by: Chandru Siddalingappa <chandru(a)linux.vnet.ibm.com>
Reviewed-by: Dave Anderson <anderson(a)redhat.com>
Cc: Haren Myneni <haren(a)us.ibm.com>
---
This looks one good. The only change that I will make is
in the map_cpu_prstatus() function -- which should just return
immediately if get_cpus_online() is equal to nd->num_prstatus_notes.
Thanks,
Dave
--- crash-4.0-8.10/ppc64.c.orig 2009-06-08 16:08:09.000000000 +0530
+++ crash-4.0-8.10/ppc64.c 2009-06-09 15:45:39.000000000 +0530
@@ -2407,13 +2407,16 @@ ppc64_paca_init(void)
if (!symbol_exists("paca"))
error(FATAL, "PPC64: Could not find 'paca' symbol\n");
- if (cpu_map_addr("present"))
+ if (cpu_map_addr("possible"))
+ map = POSSIBLE;
+ else if (cpu_map_addr("present"))
map = PRESENT;
else if (cpu_map_addr("online"))
map = ONLINE;
else
- error(FATAL,
- "PPC64: cannot find 'cpu_present_map' or 'cpu_online_map'
symbols\n");
+ error(FATAL,
+ "PPC64: cannot find 'cpu_possible_map' or\
+ 'cpu_present_map' or 'cpu_online_map' symbols\n");
if (!MEMBER_EXISTS("paca_struct", "data_offset"))
return;
@@ -2423,8 +2426,8 @@ ppc64_paca_init(void)
cpu_paca_buf = GETBUF(SIZE(ppc64_paca));
- if (!(nr_paca = get_array_length("paca", NULL, 0)))
- nr_paca = NR_CPUS;
+ if (!(nr_paca = get_array_length("paca", NULL, 0)))
+ nr_paca = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
if (nr_paca > NR_CPUS) {
error(WARNING,
@@ -2435,7 +2438,7 @@ ppc64_paca_init(void)
for (i = cpus = 0; i < nr_paca; i++) {
/*
- * CPU present (or online)?
+ * CPU present or online or can exist in the system(possible)?
*/
if (!in_cpu_map(map, i))
continue;
--- crash-4.0-8.10/kernel.c.orig 2009-06-08 16:07:53.000000000 +0530
+++ crash-4.0-8.10/kernel.c 2009-06-09 15:01:51.000000000 +0530
@@ -74,6 +74,9 @@ kernel_init()
cpu_maps_init();
+ if (KDUMP_DUMPFILE())
+ map_cpu_prstatus();
+
kt->stext = symbol_value("_stext");
kt->etext = symbol_value("_etext");
get_text_init_space();
--- crash-4.0-8.10/netdump.c.orig 2009-06-08 16:07:58.000000000 +0530
+++ crash-4.0-8.10/netdump.c 2009-06-09 16:24:52.000000000 +0530
@@ -45,6 +45,38 @@ static void check_dumpfile_size(char *);
(machine_type("IA64") || machine_type("PPC64"))
/*
+ * kdump installs NT_PRSTATUS elf notes only to the cpus
+ * that were online during dumping. Hence we call into
+ * this function after reading the cpu map from the kernel,
+ * to remap the NT_PRSTATUS notes only to the online cpus
+ */
+void map_cpu_prstatus(void)
+{
+ void *nt_ptr;
+ int i, j, nrcpus;
+
+ /* temporary buffer to hold the prstatus_percpu array */
+ if ((nt_ptr = (void *)calloc(nd->num_prstatus_notes,
+ sizeof(void *))) == NULL)
+ error(FATAL,
+ "cannot allocate a buffer to hold prstatus_percpu array\n");
+
+ memcpy((void *)nt_ptr, nd->nt_prstatus_percpu,
+ (nd->num_prstatus_notes * sizeof(void *)));
+ memset(nd->nt_prstatus_percpu, 0,
+ (nd->num_prstatus_notes * sizeof(void *)));
+
+ nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
+
+ /* re-populate the array with the notes mapping to online cpus */
+ for (i = 0, j = 0; i < nrcpus; i++)
+ if (in_cpu_map(ONLINE, i))
+ ((unsigned long *)nd->nt_prstatus_percpu)[i] =
+ ((unsigned long *)nt_ptr)[j++];
+ free(nt_ptr);
+}
+
+/*
* Determine whether a file is a netdump/diskdump/kdump creation,
* and if TRUE, initialize the vmcore_data structure.
*/
@@ -618,7 +650,7 @@ get_netdump_panic_task(void)
crashing_cpu = -1;
if (kernel_symbol_exists("crashing_cpu")) {
get_symbol_data("crashing_cpu", sizeof(int), &i);
- if ((i >= 0) && (i < nd->num_prstatus_notes)) {
+ if ((i >= 0) && in_cpu_map(ONLINE, i)) {
crashing_cpu = i;
if (CRASHDEBUG(1))
error(INFO,
@@ -2236,7 +2268,7 @@ get_netdump_regs_ppc64(struct bt_info *b
* CPUs if they responded to an IPI.
*/
if (nd->num_prstatus_notes > 1) {
- if (bt->tc->processor >= nd->num_prstatus_notes)
+ if (!nd->nt_prstatus_percpu[bt->tc->processor])
error(FATAL,
"cannot determine NT_PRSTATUS ELF note "
"for %s task: %lx\n",
3:15 p.m.
New subject: [RFC][PATCH]: crash aborts with cannot determine idle task
----- "Dave Anderson" <anderson(a)redhat.com> wrote:
This looks one good. The only change that I will make is
in the map_cpu_prstatus() function -- which should just return
immediately if get_cpus_online() is equal to nd->num_prstatus_notes.
Sorry -- that's not what I meant...
What I want to avoid is screwing around with the prstatus notes bookkeeping
unless it is absolutely necessary, i.e., where there had been some cpus offlined
prior to the crash. The original thread back in April 2008 mentioned something
to the effect that your test system only had cpus 12 and 13 online at the time of
the crash. When that is the case, is kt->cpus equal to 14? I.e., what
does the "sys" command show for "CPUS:"?
I ask because this is the way I'd prefer to go:
void
map_cpus_to_prstatus(void)
{
void **nt_ptr;
int online, i, j, nrcpus;
size_t size;
if (!(online = get_cpus_online()) || (online == kt->cpus))
return;
if (CRASHDEBUG(1))
error(INFO,
"cpus: %d online: %d NT_PRSTATUS notes: %d (remapping)\n",
kt->cpus, online, nd->num_prstatus_notes);
size = NR_CPUS * sizeof(void *);
nt_ptr = (void **)GETBUF(size);
BCOPY(nd->nt_prstatus_percpu, nt_ptr, size);
BZERO(nd->nt_prstatus_percpu, size);
/*
* Re-populate the array with the notes mapping to online cpus
*/
nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
for (i = 0, j = 0; i < nrcpus; i++) {
if (in_cpu_map(ONLINE, i))
nd->nt_prstatus_percpu[i] = nt_ptr[j++];
}
FREEBUF(nt_ptr);
}
And since kt->cpus may not be finally initialized until later than
kernel_init(), I moved the call to map_cpus_to_prstatus() to here
in task_init():
if (ACTIVE()) {
active_pid = REMOTE() ? pc->server_pid : pc->program_pid;
set_context(NO_TASK, active_pid);
tt->this_task = pid_to_task(active_pid);
}
else {
if (KDUMP_DUMPFILE())
map_cpus_to_prstatus();
please_wait("determining panic task");
set_context(get_panic_context(), NO_PID);
please_wait_done();
}
Can you test the map_cpus_to_prstatus() function above, along with the
movement of the call to it from kernel_init() to task_init()?
Thanks,
Dave
3:26 a.m.
New subject: [RFC][PATCH]: crash aborts with cannot determine idle task
Dave Anderson wrote:
Sorry -- that's not what I meant...
What I want to avoid is screwing around with the prstatus notes bookkeeping
unless it is absolutely necessary, i.e., where there had been some cpus offlined
prior to the crash. The original thread back in April 2008 mentioned something
to the effect that your test system only had cpus 12 and 13 online at the time of
the crash. When that is the case, is kt->cpus equal to 14? I.e., what
does the "sys" command show for "CPUS:"?
I had the vmcore file from that test system and ran crash with -d1.
The cpu maps shown are ...
cpu_possible_map: 0 1 2 3 4 5 6 7 8 9 10 11 12 13
cpu_present_map: 8 9 10 11 12 13
cpu_online_map: 12 13
The 'sys' command shows CPUS as '14' (with the patch applied)
<snip>
crash> sys
KERNEL: ./vmlinux
DUMPFILE: ./vmcore
CPUS: 14
DATE: Tue Mar 25 14:43:39 2008
UPTIME: 08:01:57
LOAD AVERAGE: 12.73, 5.40, 3.72
TASKS: 262
I had another vmcore collected on another system by offlining couple of
cpus through sysfs interface. The cpu maps on this machine with 'crash
-d1' show...
cpu_possible_map: 0 1 2 3
cpu_present_map: 0 1 2 3
cpu_online_map: 2 3
and 'sys' shows as
<snip>
crash> sys
KERNEL: ./vmlinux
DUMPFILE: ./vmcore
CPUS: 4
DATE: Sat Jun 6 15:00:24 2009
UPTIME: 15:56:30
I ask because this is the way I'd prefer to go:
void
map_cpus_to_prstatus(void)
{
void **nt_ptr;
int online, i, j, nrcpus;
size_t size;
if (!(online = get_cpus_online()) || (online == kt->cpus))
return;
if (CRASHDEBUG(1))
error(INFO,
"cpus: %d online: %d NT_PRSTATUS notes: %d (remapping)\n",
kt->cpus, online, nd->num_prstatus_notes);
size = NR_CPUS * sizeof(void *);
nt_ptr = (void **)GETBUF(size);
BCOPY(nd->nt_prstatus_percpu, nt_ptr, size);
BZERO(nd->nt_prstatus_percpu, size);
/*
* Re-populate the array with the notes mapping to online cpus
*/
nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
for (i = 0, j = 0; i < nrcpus; i++) {
if (in_cpu_map(ONLINE, i))
nd->nt_prstatus_percpu[i] = nt_ptr[j++];
}
FREEBUF(nt_ptr);
}
And since kt->cpus may not be finally initialized until later than
kernel_init(), I moved the call to map_cpus_to_prstatus() to here
in task_init():
if (ACTIVE()) {
active_pid = REMOTE() ? pc->server_pid : pc->program_pid;
set_context(NO_TASK, active_pid);
tt->this_task = pid_to_task(active_pid);
}
else {
if (KDUMP_DUMPFILE())
map_cpus_to_prstatus();
please_wait("determining panic task");
set_context(get_panic_context(), NO_PID);
please_wait_done();
}
Can you test the map_cpus_to_prstatus() function above, along with the
movement of the call to it from kernel_init() to task_init()?
Yes, I tested these changes and they work fine.
Thanks,
Chandru
12:21 a.m.
New subject: [RFC][PATCH]: crash aborts with cannot determine idle task
Chandru wrote:
> I ask because this is the way I'd prefer to go:
>
> void
> map_cpus_to_prstatus(void)
> {
> void **nt_ptr;
> int online, i, j, nrcpus;
> size_t size;
>
> if (!(online = get_cpus_online()) || (online == kt->cpus))
> return;
>
> if (CRASHDEBUG(1))
> error(INFO,
> "cpus: %d online: %d NT_PRSTATUS notes: %d
> (remapping)\n",
> kt->cpus, online, nd->num_prstatus_notes);
>
> size = NR_CPUS * sizeof(void *);
>
> nt_ptr = (void **)GETBUF(size);
> BCOPY(nd->nt_prstatus_percpu, nt_ptr, size);
> BZERO(nd->nt_prstatus_percpu, size);
>
> /*
> * Re-populate the array with the notes mapping to online cpus
> */
> nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
>
> for (i = 0, j = 0; i < nrcpus; i++) {
> if (in_cpu_map(ONLINE, i))
> nd->nt_prstatus_percpu[i] = nt_ptr[j++];
> }
>
> FREEBUF(nt_ptr);
> }
>
> And since kt->cpus may not be finally initialized until later than
> kernel_init(), I moved the call to map_cpus_to_prstatus() to here
> in task_init():
>
> if (ACTIVE()) {
> active_pid = REMOTE() ? pc->server_pid :
> pc->program_pid;
> set_context(NO_TASK, active_pid);
> tt->this_task = pid_to_task(active_pid);
> }
> else {
> if (KDUMP_DUMPFILE())
> map_cpus_to_prstatus();
> please_wait("determining panic task");
> set_context(get_panic_context(), NO_PID);
> please_wait_done();
> }
>
> Can you test the map_cpus_to_prstatus() function above, along with the
> movement of the call to it from kernel_init() to task_init()?
>
>
>
Yes, I tested these changes and they work fine.
Thanks,
Chandru
Hello Dave,
Could you please let me know if these changes will make it into the next
version of crash utility ?,
Thanks
Chandru
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