Re: [PATCH] mm: page_alloc: Use KERN_CONT where appropriate

[Michal Hocko]

On Tue 11-10-16 19:24:55, Joe Perches wrote:
> Recent changes to printk require KERN_CONT uses to continue logging
> messages.  So add KERN_CONT where necessary.

I was really wondering what happened when Aaron reported an allocation
failure http://lkml.kernel.org/r/20161012065423.ga16...@aaronlu.sh.intel.com
See the attached log got the current Linus' tree

Fixes: 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation 
lines")
> Signed-off-by: Joe Perches <j...@perches.com>

Acked-by: Michal Hocko <mho...@suse.com>

I believe we can simplify the code a bit as well. What do you think
about the following on top?
---
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6f8c356140a0..7e1b74ee79cb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4078,10 +4078,12 @@ unsigned long nr_free_pagecache_pages(void)
        return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
 }
 
-static inline void show_node(struct zone *zone)
+static inline void show_zone_node(struct zone *zone)
 {
        if (IS_ENABLED(CONFIG_NUMA))
-               printk("Node %d ", zone_to_nid(zone));
+               printk("Node %d %s", zone_to_nid(zone), zone->name);
+       else
+               printk("%s: ", zone->name);
 }
 
 long si_mem_available(void)
@@ -4329,9 +4331,8 @@ void show_free_areas(unsigned int filter)
                for_each_online_cpu(cpu)
                        free_pcp += per_cpu_ptr(zone->pageset, cpu)->pcp.count;
 
-               show_node(zone);
+               show_zone_node(zone);
                printk(KERN_CONT
-                       "%s"
                        " free:%lukB"
                        " min:%lukB"
                        " low:%lukB"
@@ -4354,7 +4355,6 @@ void show_free_areas(unsigned int filter)
                        " local_pcp:%ukB"
                        " free_cma:%lukB"
                        "\n",
-                       zone->name,
                        K(zone_page_state(zone, NR_FREE_PAGES)),
                        K(min_wmark_pages(zone)),
                        K(low_wmark_pages(zone)),
@@ -4379,7 +4379,6 @@ void show_free_areas(unsigned int filter)
                printk("lowmem_reserve[]:");
                for (i = 0; i < MAX_NR_ZONES; i++)
                        printk(KERN_CONT " %ld", zone->lowmem_reserve[i]);
-               printk(KERN_CONT "\n");
        }
 
        for_each_populated_zone(zone) {
@@ -4389,8 +4388,7 @@ void show_free_areas(unsigned int filter)
 
                if (skip_free_areas_node(filter, zone_to_nid(zone)))
                        continue;
-               show_node(zone);
-               printk(KERN_CONT "%s: ", zone->name);
+               show_zone_node(zone);
 
                spin_lock_irqsave(&zone->lock, flags);
                for (order = 0; order < MAX_ORDER; order++) {
-- 
Michal Hocko
SUSE Labs