The patch titled
procfs: provide stack information for threads
has been added to the -mm tree. Its filename is
procfs-provide-stack-information-for-threads-v08.patch
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out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: procfs: provide stack information for threads
From: Stefani Seibold <stefani@xxxxxxxxxxx>
A patch to give a better overview of the userland application stack usage,
especially for embedded linux.
Currently you are only able to dump the main process/thread stack usage
which is showed in /proc/pid/status by the "VmStk" Value. But you get no
information about the consumed stack memory of the the threads.
There is an enhancement in the /proc/<pid>/{task/*,}/*maps and which marks
the vm mapping where the thread stack pointer reside with "[thread stack
xxxxxxxx]". xxxxxxxx is the maximum size of stack. This is a value
information, because libpthread doesn't set the start of the stack to the
top of the mapped area, depending of the pthread usage.
A sample output of /proc/<pid>/task/<tid>/maps looks like:
08048000-08049000 r-xp 00000000 03:00 8312 /opt/z
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/z
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7d12000-a7d13000 ---p 00000000 00:00 0
a7d13000-a7f13000 rw-p 00000000 00:00 0 [thread stack: 001ff4b4]
a7f13000-a7f14000 ---p 00000000 00:00 0
a7f14000-a7f36000 rw-p 00000000 00:00 0
a7f36000-a8069000 r-xp 00000000 03:00 4222 /lib/libc.so.6
a8069000-a806b000 r--p 00133000 03:00 4222 /lib/libc.so.6
a806b000-a806c000 rw-p 00135000 03:00 4222 /lib/libc.so.6
a806c000-a806f000 rw-p 00000000 00:00 0
a806f000-a8083000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
a8083000-a8084000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
a8084000-a8085000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
a8085000-a8088000 rw-p 00000000 00:00 0
a8088000-a80a4000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
a80a4000-a80a5000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
a80a5000-a80a6000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
afaf5000-afb0a000 rw-p 00000000 00:00 0 [stack]
ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
Also there is a new entry "stack usage" in /proc/<pid>/{task/*,}/status
which will you give the current stack usage in kb.
A sample output of /proc/self/status looks like:
Name: cat
State: R (running)
Tgid: 507
Pid: 507
.
.
.
CapBnd: fffffffffffffeff
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 0
Stack usage: 12 kB
I also fixed stack base address in /proc/<pid>/{task/*,}/stat to the base
address of the associated thread stack and not the one of the main
process. This makes more sense.
Signed-off-by: Stefani Seibold <stefani@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.txt | 5 ++
fs/exec.c | 2 +
fs/proc/array.c | 51 ++++++++++++++++++++++++++-
fs/proc/task_mmu.c | 19 ++++++++++
include/linux/sched.h | 1
kernel/fork.c | 2 +
6 files changed, 78 insertions(+), 2 deletions(-)
diff -puN Documentation/filesystems/proc.txt~procfs-provide-stack-information-for-threads-v08 Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt~procfs-provide-stack-information-for-threads-v08
+++ a/Documentation/filesystems/proc.txt
@@ -176,6 +176,7 @@ read the file /proc/PID/status:
CapBnd: ffffffffffffffff
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 1
+ Stack usage: 12 kB
This shows you nearly the same information you would get if you viewed it with
the ps command. In fact, ps uses the proc file system to obtain its
@@ -229,6 +230,7 @@ Table 1-2: Contents of the statm files (
Mems_allowed_list Same as previous, but in "list format"
voluntary_ctxt_switches number of voluntary context switches
nonvoluntary_ctxt_switches number of non voluntary context switches
+ Stack usage: stack usage high water mark (round up to page size)
..............................................................................
Table 1-3: Contents of the statm files (as of 2.6.8-rc3)
@@ -307,7 +309,7 @@ address perms offset dev in
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
a7cb1000-a7cb2000 ---p 00000000 00:00 0
-a7cb2000-a7eb2000 rw-p 00000000 00:00 0
+a7cb2000-a7eb2000 rw-p 00000000 00:00 0 [thread stack: 001ff4b4]
a7eb2000-a7eb3000 ---p 00000000 00:00 0
a7eb3000-a7ed5000 rw-p 00000000 00:00 0
a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
@@ -343,6 +345,7 @@ is not associated with a file:
[stack] = the stack of the main process
[vdso] = the "virtual dynamic shared object",
the kernel system call handler
+ [thread stack, xxxxxxxx] = the stack of the thread, xxxxxxxx is the stack size
or if empty, the mapping is anonymous.
diff -puN fs/exec.c~procfs-provide-stack-information-for-threads-v08 fs/exec.c
--- a/fs/exec.c~procfs-provide-stack-information-for-threads-v08
+++ a/fs/exec.c
@@ -1344,6 +1344,8 @@ int do_execve(char * filename,
if (retval < 0)
goto out;
+ current->stack_start = current->mm->start_stack;
+
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
diff -puN fs/proc/array.c~procfs-provide-stack-information-for-threads-v08 fs/proc/array.c
--- a/fs/proc/array.c~procfs-provide-stack-information-for-threads-v08
+++ a/fs/proc/array.c
@@ -321,6 +321,54 @@ static inline void task_context_switch_c
p->nivcsw);
}
+static inline unsigned long get_stack_usage_in_bytes(struct vm_area_struct *vma,
+ struct task_struct *p)
+{
+ unsigned long i;
+ struct page *page;
+ unsigned long stkpage;
+
+ stkpage = KSTK_ESP(p) & PAGE_MASK;
+
+#ifdef CONFIG_STACK_GROWSUP
+ for (i = vma->vm_end; i-PAGE_SIZE > stkpage; i -= PAGE_SIZE) {
+
+ page = follow_page(vma, i-PAGE_SIZE, 0);
+
+ if (!IS_ERR(page) && page)
+ break;
+ }
+ return i - (p->stack_start & PAGE_MASK);
+#else
+ for (i = vma->vm_start; i+PAGE_SIZE <= stkpage; i += PAGE_SIZE) {
+
+ page = follow_page(vma, i, 0);
+
+ if (!IS_ERR(page) && page)
+ break;
+ }
+ return (p->stack_start & PAGE_MASK) - i + PAGE_SIZE;
+#endif
+}
+
+static inline void task_show_stack_usage(struct seq_file *m,
+ struct task_struct *task)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm = get_task_mm(task);
+
+ if (mm) {
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, task->stack_start);
+ if (vma)
+ seq_printf(m, "Stack usage:\t%lu kB\n",
+ get_stack_usage_in_bytes(vma, task) >> 10);
+
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ }
+}
+
int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
@@ -340,6 +388,7 @@ int proc_pid_status(struct seq_file *m,
task_show_regs(m, task);
#endif
task_context_switch_counts(m, task);
+ task_show_stack_usage(m, task);
return 0;
}
@@ -481,7 +530,7 @@ static int do_task_stat(struct seq_file
rsslim,
mm ? mm->start_code : 0,
mm ? mm->end_code : 0,
- (permitted && mm) ? mm->start_stack : 0,
+ (permitted) ? task->stack_start : 0,
esp,
eip,
/* The signal information here is obsolete.
diff -puN fs/proc/task_mmu.c~procfs-provide-stack-information-for-threads-v08 fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~procfs-provide-stack-information-for-threads-v08
+++ a/fs/proc/task_mmu.c
@@ -242,6 +242,25 @@ static void show_map_vma(struct seq_file
} else if (vma->vm_start <= mm->start_stack &&
vma->vm_end >= mm->start_stack) {
name = "[stack]";
+ } else {
+ unsigned long stack_start;
+ struct proc_maps_private *pmp;
+
+ pmp = m->private;
+ stack_start = pmp->task->stack_start;
+
+ if (vma->vm_start <= stack_start &&
+ vma->vm_end >= stack_start) {
+ pad_len_spaces(m, len);
+ seq_printf(m,
+ "[thread stack: %08lx]",
+#ifdef CONFIG_STACK_GROWSUP
+ vma->vm_end - stack_start
+#else
+ stack_start - vma->vm_start
+#endif
+ );
+ }
}
} else {
name = "[vdso]";
diff -puN include/linux/sched.h~procfs-provide-stack-information-for-threads-v08 include/linux/sched.h
--- a/include/linux/sched.h~procfs-provide-stack-information-for-threads-v08
+++ a/include/linux/sched.h
@@ -1460,6 +1460,7 @@ struct task_struct {
/* bitmask of trace recursion */
unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
+ unsigned long stack_start;
};
/* Future-safe accessor for struct task_struct's cpus_allowed. */
diff -puN kernel/fork.c~procfs-provide-stack-information-for-threads-v08 kernel/fork.c
--- a/kernel/fork.c~procfs-provide-stack-information-for-threads-v08
+++ a/kernel/fork.c
@@ -1095,6 +1095,8 @@ static struct task_struct *copy_process(
p->bts = NULL;
+ p->stack_start = stack_start;
+
/* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags);
_
Patches currently in -mm which might be from stefani@xxxxxxxxxxx are
proctxt-update-kernel-filesystem-proctxt-documentation.patch
procfs-provide-stack-information-for-threads-v08.patch
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