procfs: provide stack information for threads
Stefani Seibold [Tue, 22 Sep 2009 23:45:40 +0000 (16:45 -0700)]
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>

Documentation/filesystems/proc.txt
fs/exec.c
fs/proc/array.c
fs/proc/task_mmu.c
include/linux/sched.h
kernel/fork.c
mm/Makefile

index 75988ba..b5aee78 100644 (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.
 
index 69bb9d8..5c833c1 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -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;
index 725a650..0c6bc60 100644 (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.
index 366b101..2a1bef9 100644 (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]";
index 6448bbc..3cbc6c0 100644 (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. */
index 7cf4581..8f45b0e 100644 (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);
 
index 728a9fd..88193d7 100644 (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