/proc/pid/maps: don't show pgoff of pure ANON VMAs

Recently, it's argued that what proc/pid/maps shows is ugly when a 32bit
binary runs on 64bit host.

/proc/pid/maps outputs vma's pgoff member but vma->pgoff is of no use
information is the vma is for ANON.  With this patch, /proc/pid/maps shows
just 0 if no file backing store.

[akpm@linux-foundation.org: coding-style fixes]
[kamezawa.hiroyu@jp.fujitsu.com: coding-style fixes]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mike Waychison <mikew@google.com>
Reported-by: Ying Han <yinghan@google.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index b0ae0be4801f..39e4ad4f59f4 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -204,6 +204,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
         struct file *file = vma->vm_file;
         int flags = vma->vm_flags;
         unsigned long ino = 0;
+        unsigned long long pgoff = 0;
         dev_t dev = 0;
         int len;
 
@@ -211,6 +212,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
                 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
                 dev = inode->i_sb->s_dev;
                 ino = inode->i_ino;
+                pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
         }
 
         seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
@@ -220,7 +222,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
                         flags & VM_WRITE ? 'w' : '-',
                         flags & VM_EXEC ? 'x' : '-',
                         flags & VM_MAYSHARE ? 's' : 'p',
-                        ((loff_t)vma->vm_pgoff) << PAGE_SHIFT,
+                        pgoff,
                         MAJOR(dev), MINOR(dev), ino, &len);
 
         /*