On Fri, Jun 23, 2023 at 3:34 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> wrote:
From: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
(The following commit is now in linux-next.)
Thanks for the early fix, Kazu.
Looks good to me. So: Ack.
Lianbo
Kernel commit 757777eef55b ("pid: Replace struct pid 1-element array
with flex-array") changed pid.numbers[1] to pid.numbers[]. With this,
the size of struct pid does not contain the size of struct upid:
(gdb) ptype /o struct pid
/* offset | size */ type = struct pid {
/* 0 | 4 */ refcount_t count;
...
/* 96 | 0 */ struct upid numbers[];
^^^^ ^^^
/* total size (bytes): 96 */
} ^^^^
As a result, in refresh_xarray_task_table(), crash does not read the
data of pid.numbers[0].ns and cannot gather the task table correctly.
$ crash vmlinux vmcore
...
WARNING: active task ffff936992ad0000 on cpu 1 not found in PID hash
...
crash> ps -S
RU: 9
crash>
Increase the size of reading struct pid by SIZE(upid) in this case.
Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
---
defs.h | 1 +
symbols.c | 3 +++
task.c | 10 ++++++++--
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/defs.h b/defs.h
index 3e7d6cfbc6a8..dc7c822055f0 100644
--- a/defs.h
+++ b/defs.h
@@ -2424,6 +2424,7 @@ struct array_table {
int task_struct_rlim;
int signal_struct_rlim;
int vm_numa_stat;
+ int pid_numbers;
};
/*
diff --git a/symbols.c b/symbols.c
index 7b1d59203b90..ec2878bf41d6 100644
--- a/symbols.c
+++ b/symbols.c
@@ -8741,6 +8741,8 @@ builtin_array_length(char *s, int len, int *two_dim)
lenptr = &array_table.signal_struct_rlim;
else if (STREQ(s, "vm_numa_stat"))
lenptr = &array_table.vm_numa_stat;
+ else if (STREQ(s, "pid.numbers"))
+ lenptr = &array_table.pid_numbers;
if (!lenptr) /* not stored */
return(len);
@@ -11139,6 +11141,7 @@ dump_offset_table(char *spec, ulong makestruct)
ARRAY_LENGTH(signal_struct_rlim));
fprintf(fp, " vm_numa_stat: %d\n",
ARRAY_LENGTH(vm_numa_stat));
+ fprintf(fp, " pid_numbers: %d\n", ARRAY_LENGTH(pid_numbers));
if (spec) {
int in_size_table, in_array_table, arrays, offsets, sizes;
diff --git a/task.c b/task.c
index 2b7467b4193d..d1af4df025b9 100644
--- a/task.c
+++ b/task.c
@@ -352,6 +352,7 @@ task_init(void)
MEMBER_OFFSET_INIT(upid_ns, "upid", "ns");
MEMBER_OFFSET_INIT(upid_pid_chain, "upid", "pid_chain");
MEMBER_OFFSET_INIT(pid_numbers, "pid", "numbers");
+ ARRAY_LENGTH_INIT(len, pid_numbers, "pid.numbers", NULL, 0);
MEMBER_OFFSET_INIT(pid_tasks, "pid", "tasks");
tt->init_pid_ns = symbol_value("init_pid_ns");
}
@@ -2574,6 +2575,7 @@ refresh_xarray_task_table(void)
char *tp;
struct list_pair xp;
char *pidbuf;
+ long pid_size = SIZE(pid);
if (DUMPFILE() && (tt->flags & TASK_INIT_DONE)) /* impossible */
return;
@@ -2603,8 +2605,12 @@ refresh_xarray_task_table(void)
if (CRASHDEBUG(1))
console("xarray: count: %ld\n", count);
+ /* 6.5: 757777eef55b changed pid.numbers[1] to numbers[] */
+ if (ARRAY_LENGTH(pid_numbers) == 0)
+ pid_size += SIZE(upid);
+
retries = 0;
- pidbuf = GETBUF(SIZE(pid));
+ pidbuf = GETBUF(pid_size);
retry_xarray:
if (retries && DUMPFILE())
@@ -2672,7 +2678,7 @@ retry_xarray:
* - get task from address of task->pids[0]
*/
if (!readmem(next, KVADDR, pidbuf,
- SIZE(pid), "pid", RETURN_ON_ERROR|QUIET)) {
+ pid_size, "pid", RETURN_ON_ERROR|QUIET)) {
error(INFO, "\ncannot read pid struct from xarray\n");
if (DUMPFILE())
continue;
--
2.31.1
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