x86: stop nmi softlockup warnings in show_mem()

When dumping memory via sysrq-m it is possible to take a bogus NMI
watchdog or softlockup watchdog because the dump can take a long time on
big memory systems.

Occasionally tickle the watchdog when doing the dump.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index bbaa2b15393412d52cce174549f01f25abc9e0c8..be61a1d845a4a5e9fffbe5ccd9a80c9650d45e62 100644 (file)
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -6,6 +6,7 @@
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/mm.h>
+#include <linux/nmi.h>
 #include <linux/swap.h>
 #include <linux/smp.h>
 #include <linux/highmem.h>
@@ -39,6 +40,8 @@ void show_mem(void)
        for_each_online_pgdat(pgdat) {
                pgdat_resize_lock(pgdat, &flags);
                for (i = 0; i < pgdat->node_spanned_pages; ++i) {
+                       if (unlikely(i % MAX_ORDER_NR_PAGES == 0))
+                               touch_nmi_watchdog();
                        page = pgdat_page_nr(pgdat, i);
                        total++;
                        if (PageHighMem(page))