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procfs: provide stack information for threads

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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.

[akpm@linux-foundation.org: fs/proc/array.c now needs walk_page_range()]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Stefani Seibold 2009-09-22 16:45:40 -07:00 committed by Linus Torvalds
parent cba8aafe1e
commit d899bf7b55
7 changed files with 114 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
Documentation/filesystems/proc.txt
View file

@ -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 (as of 2.6.30-rc7)
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 inode pathname
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 [threadstack: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
[threadstack:xxxxxxxx] = the stack of the thread, xxxxxxxx is the stack size
or if empty, the mapping is anonymous.

2
fs/exec.c
View file

@ -1357,6 +1357,8 @@ 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;

85
fs/proc/array.c
View file

@ -82,6 +82,7 @@
#include <linux/pid_namespace.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/swapops.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
@ -321,6 +322,87 @@ static inline void task_context_switch_counts(struct seq_file *m,
p->nivcsw);
}
struct stack_stats {
struct vm_area_struct *vma;
unsigned long startpage;
unsigned long usage;
};
static int stack_usage_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
struct stack_stats *ss = walk->private;
struct vm_area_struct *vma = ss->vma;
pte_t *pte, ptent;
spinlock_t *ptl;
int ret = 0;
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE) {
ptent = *pte;
#ifdef CONFIG_STACK_GROWSUP
if (pte_present(ptent) || is_swap_pte(ptent))
ss->usage = addr - ss->startpage + PAGE_SIZE;
#else
if (pte_present(ptent) || is_swap_pte(ptent)) {
ss->usage = ss->startpage - addr + PAGE_SIZE;
pte++;
ret = 1;
break;
}
#endif
}
pte_unmap_unlock(pte - 1, ptl);
cond_resched();
return ret;
}
static inline unsigned long get_stack_usage_in_bytes(struct vm_area_struct *vma,
struct task_struct *task)
{
struct stack_stats ss;
struct mm_walk stack_walk = {
.pmd_entry = stack_usage_pte_range,
.mm = vma->vm_mm,
.private = &ss,
};
if (!vma->vm_mm || is_vm_hugetlb_page(vma))
return 0;
ss.vma = vma;
ss.startpage = task->stack_start & PAGE_MASK;
ss.usage = 0;
#ifdef CONFIG_STACK_GROWSUP
walk_page_range(KSTK_ESP(task) & PAGE_MASK, vma->vm_end,
&stack_walk);
#else
walk_page_range(vma->vm_start, (KSTK_ESP(task) & PAGE_MASK) + PAGE_SIZE,
&stack_walk);
#endif
return ss.usage;
}
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 +422,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
task_show_regs(m, task);
#endif
task_context_switch_counts(m, task);
task_show_stack_usage(m, task);
return 0;
}
@ -481,7 +564,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
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.

19
fs/proc/task_mmu.c
View file

@ -243,6 +243,25 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
} 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,
"[threadstack:%08lx]",
#ifdef CONFIG_STACK_GROWSUP
vma->vm_end - stack_start
#else
stack_start - vma->vm_start
#endif
);
}
}
} else {
name = "[vdso]";

1
include/linux/sched.h
View file

@ -1529,6 +1529,7 @@ 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. */

2
kernel/fork.c
View file

@ -1095,6 +1095,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->bts = NULL;
p->stack_start = stack_start;
/* Perform scheduler related setup. Assign this task to a CPU. */
sched_fork(p, clone_flags);

4
mm/Makefile
View file

@ -11,10 +11,10 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
page_isolation.o mm_init.o mmu_context.o $(mmu-y)
page_isolation.o mm_init.o mmu_context.o \
pagewalk.o $(mmu-y)
obj-y += init-mm.o
obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o
obj-$(CONFIG_BOUNCE) += bounce.o
obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o
obj-$(CONFIG_HAS_DMA) += dmapool.o