[PATCH] procfs: Use proper units for noMMU statm

[PATCH] procfs: Use proper units for noMMU statm

[steve]

On no-MMU systems, sizes reported in /proc/n/statm have units of bytes. 
Per Documentation/filesystems/proc.txt, these values should be in pages.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
---
diff -uprN a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
--- a/fs/proc/task_nommu.c	2009-11-13 16:48:14.000000000 -0600
+++ b/fs/proc/task_nommu.c	2009-11-13 16:51:09.000000000 -0600
@@ -110,8 +110,11 @@ int task_statm(struct mm_struct *mm, int
 		}
 	}
 
-	size += (*text = mm->end_code - mm->start_code);
-	size += (*data = mm->start_stack - mm->start_data);
+	size >>= PAGE_SHIFT;
+	*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
+		>> PAGE_SHIFT;
+	*data = (mm->start_stack - mm->start_data) >> PAGE_SHIFT;
+	size += *text + *data;
 	up_read(&mm->mmap_sem);
 	*resident = size;
 	return size;

Re: [PATCH] procfs: Use proper units for noMMU statm

[Américo Wang]

On Fri, Nov 13, 2009 at 07:52:14PM -0600, steve@digidescorp.com wrote:
>On no-MMU systems, sizes reported in /proc/n/statm have units of bytes. 
>Per Documentation/filesystems/proc.txt, these values should be in pages.
>
>Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
>---
>diff -uprN a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
>--- a/fs/proc/task_nommu.c	2009-11-13 16:48:14.000000000 -0600
>+++ b/fs/proc/task_nommu.c	2009-11-13 16:51:09.000000000 -0600
>@@ -110,8 +110,11 @@ int task_statm(struct mm_struct *mm, int
> 		}
> 	}
> 
>-	size += (*text = mm->end_code - mm->start_code);
>-	size += (*data = mm->start_stack - mm->start_data);
>+	size >>= PAGE_SHIFT;
>+	*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
>+		>> PAGE_SHIFT;
>+	*data = (mm->start_stack - mm->start_data) >> PAGE_SHIFT;

Are '->start_stack' and '->start_data' already page aligned on NOMMU arch?

If yes, this patch looks good.


>+	size += *text + *data;
> 	up_read(&mm->mmap_sem);
> 	*resident = size;
> 	return size;
>
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Re: [PATCH] procfs: Use proper units for noMMU statm

[Steven J. Magnani]

On Sat, 2009-11-14 at 12:41 +0800, Américo Wang wrote:
> On Fri, Nov 13, 2009 at 07:52:14PM -0600, steve@digidescorp.com wrote:
> >On no-MMU systems, sizes reported in /proc/n/statm have units of bytes. 
> >Per Documentation/filesystems/proc.txt, these values should be in pages.
> >
> > ...
> >
> >+	*data = (mm->start_stack - mm->start_data) >> PAGE_SHIFT;
> 
> Are '->start_stack' and '->start_data' already page aligned on NOMMU arch?
> 

In looking over binfmt_flat.c (main executable type for noMMU systems),
I don't think there's a guarantee of more than 32- or 64-bit alignment.
Thanks for the suggestion, I'll submit an updated patch.

------------------------------------------------------------------------
 Steven J. Magnani               "I claim this network for MARS!
 www.digidescorp.com              Earthling, return my space modulator!"

 #include <standard.disclaimer>

[PATCH v2] procfs: Use proper units for noMMU statm

[steve]

Reworked to guarantee page alignment of terms used in data size calculation
and to reduce time spent with mmap_sem held.

On no-MMU systems, sizes reported in /proc/n/statm have units of bytes. 
Per Documentation/filesystems/proc.txt, these values should be in pages.

Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
---

diff -uprN a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
--- a/fs/proc/task_nommu.c	2009-11-13 16:48:14.000000000 -0600
+++ b/fs/proc/task_nommu.c	2009-11-14 12:17:00.000000000 -0600
@@ -110,9 +110,13 @@ int task_statm(struct mm_struct *mm, int
 		}
 	}
 
-	size += (*text = mm->end_code - mm->start_code);
-	size += (*data = mm->start_stack - mm->start_data);
+	*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
+		>> PAGE_SHIFT;
+	*data = (PAGE_ALIGN(mm->start_stack) - (mm->start_data & PAGE_MASK))
+		>> PAGE_SHIFT;
 	up_read(&mm->mmap_sem);
+	size >>= PAGE_SHIFT;
+	size += *text + *data;
 	*resident = size;
 	return size;
 }