mm: vmalloc: show number of vmalloc pages in /proc/meminfo

Vmalloc() is getting more and more used these days (kernel stacks, bpf and
percpu allocator are new top users), and the total % of memory consumed by
vmalloc() can be pretty significant and changes dynamically.

/proc/meminfo is the best place to display this information: its top goal
is to show top consumers of the memory.

Since the VmallocUsed field in /proc/meminfo is not in use for quite a
long time (it has been defined to 0 by a5ad88ce8c7f ("mm: get rid of
'vmalloc_info' from /proc/meminfo")), let's reuse it for showing the
actual physical memory consumption of vmalloc().

Link: http://lkml.kernel.org/r/20190417194002.12369-3-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 568d90e17c17d4d7358ee56c544638a140538a36..465ea0153b2a34df85207fbb4971cda0ea72af57 100644 (file)
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -120,7 +120,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
        show_val_kb(m, "Committed_AS:   ", committed);
        seq_printf(m, "VmallocTotal:   %8lu kB\n",
                   (unsigned long)VMALLOC_TOTAL >> 10);
-       show_val_kb(m, "VmallocUsed:    ", 0ul);
+       show_val_kb(m, "VmallocUsed:    ", vmalloc_nr_pages());
        show_val_kb(m, "VmallocChunk:   ", 0ul);
        show_val_kb(m, "Percpu:         ", pcpu_nr_pages());
 

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 51e131245379afe953dccc915051d79179e87399..9b21d0047710e60ed2e08e2e7d8e034187b34f01 100644 (file)
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -72,10 +72,12 @@ extern void vm_unmap_aliases(void);
 
 #ifdef CONFIG_MMU
 extern void __init vmalloc_init(void);
+extern unsigned long vmalloc_nr_pages(void);
 #else
 static inline void vmalloc_init(void)
 {
 }
+static inline unsigned long vmalloc_nr_pages(void) { return 0; }
 #endif
 
 extern void *vmalloc(unsigned long size);

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index edb212298c8a24ab1f0496662d9d23cec794ec62..4fa8d84599b0bad60d03c87243c9cf97ec9bb52e 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -406,6 +406,13 @@ static void purge_vmap_area_lazy(void);
 static BLOCKING_NOTIFIER_HEAD(vmap_notify_list);
 static unsigned long lazy_max_pages(void);
 
+static atomic_long_t nr_vmalloc_pages;
+
+unsigned long vmalloc_nr_pages(void)
+{
+       return atomic_long_read(&nr_vmalloc_pages);
+}
+
 static struct vmap_area *__find_vmap_area(unsigned long addr)
 {
        struct rb_node *n = vmap_area_root.rb_node;
@@ -2237,6 +2244,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
                        BUG_ON(!page);
                        __free_pages(page, 0);
                }
+               atomic_long_sub(area->nr_pages, &nr_vmalloc_pages);
 
                kvfree(area->pages);
        }
@@ -2414,12 +2422,14 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
                if (unlikely(!page)) {
                        /* Successfully allocated i pages, free them in __vunmap() */
                        area->nr_pages = i;
+                       atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
                        goto fail;
                }
                area->pages[i] = page;
                if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
                        cond_resched();
        }
+       atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
 
        if (map_vm_area(area, prot, pages))
                goto fail;