linux-hardened/lib/show_mem.c
David Rientjes 4b59e6c473 mm, show_mem: suppress page counts in non-blockable contexts
On large systems with a lot of memory, walking all RAM to determine page
types may take a half second or even more.

In non-blockable contexts, the page allocator will emit a page allocation
failure warning unless __GFP_NOWARN is specified.  In such contexts, irqs
are typically disabled and such a lengthy delay may even result in NMI
watchdog timeouts.

To fix this, suppress the page walk in such contexts when printing the
page allocation failure warning.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-29 15:54:28 -07:00

66 lines
1.4 KiB
C

/*
* Generic show_mem() implementation
*
* Copyright (C) 2008 Johannes Weiner <hannes@saeurebad.de>
* All code subject to the GPL version 2.
*/
#include <linux/mm.h>
#include <linux/nmi.h>
#include <linux/quicklist.h>
void show_mem(unsigned int filter)
{
pg_data_t *pgdat;
unsigned long total = 0, reserved = 0, shared = 0,
nonshared = 0, highmem = 0;
printk("Mem-Info:\n");
show_free_areas(filter);
if (filter & SHOW_MEM_FILTER_PAGE_COUNT)
return;
for_each_online_pgdat(pgdat) {
unsigned long i, flags;
pgdat_resize_lock(pgdat, &flags);
for (i = 0; i < pgdat->node_spanned_pages; i++) {
struct page *page;
unsigned long pfn = pgdat->node_start_pfn + i;
if (unlikely(!(i % MAX_ORDER_NR_PAGES)))
touch_nmi_watchdog();
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
if (PageHighMem(page))
highmem++;
if (PageReserved(page))
reserved++;
else if (page_count(page) == 1)
nonshared++;
else if (page_count(page) > 1)
shared += page_count(page) - 1;
total++;
}
pgdat_resize_unlock(pgdat, &flags);
}
printk("%lu pages RAM\n", total);
#ifdef CONFIG_HIGHMEM
printk("%lu pages HighMem\n", highmem);
#endif
printk("%lu pages reserved\n", reserved);
printk("%lu pages shared\n", shared);
printk("%lu pages non-shared\n", nonshared);
#ifdef CONFIG_QUICKLIST
printk("%lu pages in pagetable cache\n",
quicklist_total_size());
#endif
}