mm: /proc/pid/*maps remove is_pid and related wrappers

Patch series "cleanups and refactor of /proc/pid/smaps*".

The recent regression in /proc/pid/smaps made me look more into the code.
Especially the issues with smaps_rollup reported in [1] as explained in
Patch 4, which fixes them by refactoring the code. Patches 2 and 3 are
preparations for that. Patch 1 is me realizing that there's a lot of
boilerplate left from times where we tried (unsuccessfuly) to mark thread
stacks in the output.

Originally I had also plans to rework the translation from
/proc/pid/*maps* file offsets to the internal structures. Now the offset
means "vma number", which is not really stable (vma's can come and go
between read() calls) and there's an extra caching of last vma's address.
My idea was that offsets would be interpreted directly as addresses, which
would also allow meaningful seeks (see the ugly seek_to_smaps_entry() in
tools/testing/selftests/vm/mlock2.h). However loff_t is (signed) long
long so that might be insufficient somewhere for the unsigned long
addresses.

So the result is fixed issues with skewed /proc/pid/smaps_rollup results,
simpler smaps code, and a lot of unused code removed.

[1] https://marc.info/?l=linux-mm&m=151927723128134&w=2

This patch (of 4):

Commit b76437579d13 ("procfs: mark thread stack correctly in
proc/<pid>/maps") introduced differences between /proc/PID/maps and
/proc/PID/task/TID/maps to mark thread stacks properly, and this was
also done for smaps and numa_maps. However it didn't work properly and
was ultimately removed by commit b18cb64ead40 ("fs/proc: Stop trying to
report thread stacks").

Now the is_pid parameter for the related show_*() functions is unused
and we can remove it together with wrapper functions and ops structures
that differ for PID and TID cases only in this parameter.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Vlastimil Babka <[e-mail]>
Reviewed-by: Alexey Dobriyan <[e-mail]>
Cc: Daniel Colascione <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/proc/base.c

···
 	REG("cmdline",   S_IRUGO, proc_pid_cmdline_ops),
 	ONE("stat",      S_IRUGO, proc_tid_stat),
 	ONE("statm",     S_IRUGO, proc_pid_statm),
-	REG("maps",      S_IRUGO, proc_tid_maps_operations),
+	REG("maps",      S_IRUGO, proc_pid_maps_operations),
 #ifdef CONFIG_PROC_CHILDREN
 	REG("children",  S_IRUGO, proc_tid_children_operations),
 #endif
 #ifdef CONFIG_NUMA
-	REG("numa_maps", S_IRUGO, proc_tid_numa_maps_operations),
+	REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations),
 #endif
 	REG("mem",       S_IRUSR|S_IWUSR, proc_mem_operations),
 	LNK("cwd",       proc_cwd_link),
···
 	REG("mountinfo",  S_IRUGO, proc_mountinfo_operations),
 #ifdef CONFIG_PROC_PAGE_MONITOR
 	REG("clear_refs", S_IWUSR, proc_clear_refs_operations),
-	REG("smaps",     S_IRUGO, proc_tid_smaps_operations),
+	REG("smaps",     S_IRUGO, proc_pid_smaps_operations),
 	REG("smaps_rollup", S_IRUGO, proc_pid_smaps_rollup_operations),
 	REG("pagemap",    S_IRUSR, proc_pagemap_operations),
 #endif

fs/proc/internal.h

···
 struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
 
 extern const struct file_operations proc_pid_maps_operations;
-extern const struct file_operations proc_tid_maps_operations;
 extern const struct file_operations proc_pid_numa_maps_operations;
-extern const struct file_operations proc_tid_numa_maps_operations;
 extern const struct file_operations proc_pid_smaps_operations;
 extern const struct file_operations proc_pid_smaps_rollup_operations;
-extern const struct file_operations proc_tid_smaps_operations;
 extern const struct file_operations proc_clear_refs_operations;
 extern const struct file_operations proc_pagemap_operations;
 

fs/proc/task_mmu.c

···
 }
 
 static void
-show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
+show_map_vma(struct seq_file *m, struct vm_area_struct *vma)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct file *file = vma->vm_file;
···
 	seq_putc(m, '\n');
 }
 
-static int show_map(struct seq_file *m, void *v, int is_pid)
+static int show_map(struct seq_file *m, void *v)
 {
-	show_map_vma(m, v, is_pid);
+	show_map_vma(m, v);
 	m_cache_vma(m, v);
 	return 0;
-}
-
-static int show_pid_map(struct seq_file *m, void *v)
-{
-	return show_map(m, v, 1);
-}
-
-static int show_tid_map(struct seq_file *m, void *v)
-{
-	return show_map(m, v, 0);
 }
 
 static const struct seq_operations proc_pid_maps_op = {
 	.start	= m_start,
 	.next	= m_next,
 	.stop	= m_stop,
-	.show	= show_pid_map
-};
-
-static const struct seq_operations proc_tid_maps_op = {
-	.start	= m_start,
-	.next	= m_next,
-	.stop	= m_stop,
-	.show	= show_tid_map
+	.show	= show_map
 };
 
 static int pid_maps_open(struct inode *inode, struct file *file)
···
 	return do_maps_open(inode, file, &proc_pid_maps_op);
 }
 
-static int tid_maps_open(struct inode *inode, struct file *file)
-{
-	return do_maps_open(inode, file, &proc_tid_maps_op);
-}
-
 const struct file_operations proc_pid_maps_operations = {
 	.open		= pid_maps_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= proc_map_release,
-};
-
-const struct file_operations proc_tid_maps_operations = {
-	.open		= tid_maps_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= proc_map_release,
···
 
 #define SEQ_PUT_DEC(str, val) \
 		seq_put_decimal_ull_width(m, str, (val) >> 10, 8)
-static int show_smap(struct seq_file *m, void *v, int is_pid)
+static int show_smap(struct seq_file *m, void *v)
 {
 	struct proc_maps_private *priv = m->private;
 	struct vm_area_struct *vma = v;
···
 		mss->pss_locked += mss->pss;
 
 	if (!rollup_mode) {
-		show_map_vma(m, vma, is_pid);
+		show_map_vma(m, vma);
 	} else if (last_vma) {
 		show_vma_header_prefix(
 			m, mss->first_vma_start, vma->vm_end, 0, 0, 0, 0);
···
 }
 #undef SEQ_PUT_DEC
 
-static int show_pid_smap(struct seq_file *m, void *v)
-{
-	return show_smap(m, v, 1);
-}
-
-static int show_tid_smap(struct seq_file *m, void *v)
-{
-	return show_smap(m, v, 0);
-}
-
 static const struct seq_operations proc_pid_smaps_op = {
 	.start	= m_start,
 	.next	= m_next,
 	.stop	= m_stop,
-	.show	= show_pid_smap
-};
-
-static const struct seq_operations proc_tid_smaps_op = {
-	.start	= m_start,
-	.next	= m_next,
-	.stop	= m_stop,
-	.show	= show_tid_smap
+	.show	= show_smap
 };
 
 static int pid_smaps_open(struct inode *inode, struct file *file)
···
 	return 0;
 }
 
-static int tid_smaps_open(struct inode *inode, struct file *file)
-{
-	return do_maps_open(inode, file, &proc_tid_smaps_op);
-}
-
 const struct file_operations proc_pid_smaps_operations = {
 	.open		= pid_smaps_open,
 	.read		= seq_read,
···
 
 const struct file_operations proc_pid_smaps_rollup_operations = {
 	.open		= pid_smaps_rollup_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= proc_map_release,
-};
-
-const struct file_operations proc_tid_smaps_operations = {
-	.open		= tid_smaps_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= proc_map_release,
···
 /*
  * Display pages allocated per node and memory policy via /proc.
  */
-static int show_numa_map(struct seq_file *m, void *v, int is_pid)
+static int show_numa_map(struct seq_file *m, void *v)
 {
 	struct numa_maps_private *numa_priv = m->private;
 	struct proc_maps_private *proc_priv = &numa_priv->proc_maps;
···
 	return 0;
 }
 
-static int show_pid_numa_map(struct seq_file *m, void *v)
-{
-	return show_numa_map(m, v, 1);
-}
-
-static int show_tid_numa_map(struct seq_file *m, void *v)
-{
-	return show_numa_map(m, v, 0);
-}
-
 static const struct seq_operations proc_pid_numa_maps_op = {
 	.start  = m_start,
 	.next   = m_next,
 	.stop   = m_stop,
-	.show   = show_pid_numa_map,
+	.show   = show_numa_map,
 };
-
-static const struct seq_operations proc_tid_numa_maps_op = {
-	.start  = m_start,
-	.next   = m_next,
-	.stop   = m_stop,
-	.show   = show_tid_numa_map,
-};
-
-static int numa_maps_open(struct inode *inode, struct file *file,
-			  const struct seq_operations *ops)
-{
-	return proc_maps_open(inode, file, ops,
-				sizeof(struct numa_maps_private));
-}
 
 static int pid_numa_maps_open(struct inode *inode, struct file *file)
 {
-	return numa_maps_open(inode, file, &proc_pid_numa_maps_op);
-}
-
-static int tid_numa_maps_open(struct inode *inode, struct file *file)
-{
-	return numa_maps_open(inode, file, &proc_tid_numa_maps_op);
+	return proc_maps_open(inode, file, &proc_pid_numa_maps_op,
+				sizeof(struct numa_maps_private));
 }
 
 const struct file_operations proc_pid_numa_maps_operations = {
···
 	.release	= proc_map_release,
 };
 
-const struct file_operations proc_tid_numa_maps_operations = {
-	.open		= tid_numa_maps_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= proc_map_release,
-};
 #endif /* CONFIG_NUMA */

fs/proc/task_nommu.c

···
 /*
  * display a single VMA to a sequenced file
  */
-static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
-			  int is_pid)
+static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	unsigned long ino = 0;
···
 /*
  * display mapping lines for a particular process's /proc/pid/maps
  */
-static int show_map(struct seq_file *m, void *_p, int is_pid)
+static int show_map(struct seq_file *m, void *_p)
 {
 	struct rb_node *p = _p;
 
-	return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb),
-			      is_pid);
-}
-
-static int show_pid_map(struct seq_file *m, void *_p)
-{
-	return show_map(m, _p, 1);
-}
-
-static int show_tid_map(struct seq_file *m, void *_p)
-{
-	return show_map(m, _p, 0);
+	return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb));
 }
 
 static void *m_start(struct seq_file *m, loff_t *pos)
···
 	.start	= m_start,
 	.next	= m_next,
 	.stop	= m_stop,
-	.show	= show_pid_map
-};
-
-static const struct seq_operations proc_tid_maps_ops = {
-	.start	= m_start,
-	.next	= m_next,
-	.stop	= m_stop,
-	.show	= show_tid_map
+	.show	= show_map
 };
 
 static int maps_open(struct inode *inode, struct file *file,
···
 	return maps_open(inode, file, &proc_pid_maps_ops);
 }
 
-static int tid_maps_open(struct inode *inode, struct file *file)
-{
-	return maps_open(inode, file, &proc_tid_maps_ops);
-}
-
 const struct file_operations proc_pid_maps_operations = {
 	.open		= pid_maps_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= map_release,
-};
-
-const struct file_operations proc_tid_maps_operations = {
-	.open		= tid_maps_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
 	.release	= map_release,