[PATCH v2] include/linux/nodemask.h: Use nr_node_ids (not MAX_NUMNODES) in __nodemask_pr_numnodes()

[PATCH v2] include/linux/nodemask.h: Use nr_node_ids (not MAX_NUMNODES) in __nodemask_pr_numnodes()

[Waiman Long]

When viewing the /proc/<pid>/status file, one can see output lines like

  Cpus_allowed:	ffffffff,ffffffff,ffffffff
  Cpus_allowed_list:	0-95
  Mems_allowed:	00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,0000000f
  Mems_allowed_list:	0-3

The "Mems_allowed" line uses the "%*pb" format string while the
"Mems_allowed_list" line uses the "%*pbl" format string together with
the nodemask_pr_args() macro.

The "Mems_allowed" looks insane compared with the others.  It is because
the nodemask_pr_args() macro uses MAX_NUMNODES as the number of nodes
to iterate. The cpumask_pr_args() macro uses nr_cpu_ids instead of
MAX_CPUS. For nodes, there is a corresponding nr_node_ids.  So it makes
sense to use nr_node_ids instead to be consistent with "Cpus_allowed:".

With that change, the "Mems_allowed" line becomes sane again.

  Mems_allowed:	f

There are currently 10 call sites of nodemask_pr_args() in the kernel.
Of them, only cpuset_task_status_allowed() in kernel/cgroup/cpuset.c
uses the "%*pb" format string that will be affected by this change. That
cpuset function is called by proc_pid_status() only.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 include/linux/nodemask.h | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 5a30ad5..ba07661 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -97,6 +97,8 @@
 
 typedef struct { DECLARE_BITMAP(bits, MAX_NUMNODES); } nodemask_t;
 extern nodemask_t _unused_nodemask_arg_;
+extern int nr_node_ids;
+extern int nr_online_nodes;
 
 /**
  * nodemask_pr_args - printf args to output a nodemask
@@ -108,7 +110,7 @@
 				__nodemask_pr_bits(maskp)
 static inline unsigned int __nodemask_pr_numnodes(const nodemask_t *m)
 {
-	return m ? MAX_NUMNODES : 0;
+	return m ? nr_node_ids : 0;
 }
 static inline const unsigned long *__nodemask_pr_bits(const nodemask_t *m)
 {
@@ -444,9 +446,6 @@ static inline int next_memory_node(int nid)
 	return next_node(nid, node_states[N_MEMORY]);
 }
 
-extern int nr_node_ids;
-extern int nr_online_nodes;
-
 static inline void node_set_online(int nid)
 {
 	node_set_state(nid, N_ONLINE);
-- 
1.8.3.1

Re: [PATCH v2] include/linux/nodemask.h: Use nr_node_ids (not MAX_NUMNODES) in __nodemask_pr_numnodes()

[Oscar Salvador]

On Tue, Dec 18, 2018 at 04:38:42PM -0500, Waiman Long wrote:
> Signed-off-by: Waiman Long <longman@redhat.com>

Looks good to me

Reviewed-by: Oscar Salvador <osalvador@suse.de>
-- 
Oscar Salvador
SUSE L3

Re: [PATCH v2] include/linux/nodemask.h: Use nr_node_ids (not MAX_NUMNODES) in __nodemask_pr_numnodes()

[kbuild test robot]

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Hi Waiman,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc7 next-20181218]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Waiman-Long/include-linux-nodemask-h-Use-nr_node_ids-not-MAX_NUMNODES-in-__nodemask_pr_numnodes/20181219-110121
config: arm-omap2plus_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.2.0 make.cross ARCH=arm 

All errors (new ones prefixed by >>):

   kernel/cgroup/cpuset.o: In function `cpuset_common_seq_show':
>> cpuset.c:(.text+0xe2c): undefined reference to `nr_node_ids'
   kernel/cgroup/cpuset.o: In function `cpuset_print_current_mems_allowed':
   cpuset.c:(.text+0x4624): undefined reference to `nr_node_ids'
   kernel/cgroup/cpuset.o: In function `cpuset_task_status_allowed':
   cpuset.c:(.text+0x4d5c): undefined reference to `nr_node_ids'
   mm/oom_kill.o: In function `dump_header':
   oom_kill.c:(.text.unlikely+0x3c4): undefined reference to `nr_node_ids'
   mm/page_alloc.o: In function `warn_alloc':
   page_alloc.c:(.text+0x4ae0): undefined reference to `nr_node_ids'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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