CONFIG_KASAN=y needs a lot of virtual memory mapped for its shadow.
In that case ptdump_walk_pgd_level_core() takes a lot of time to
walk across all page tables and doing this without
a rescheduling causes soft lockups:
NMI watchdog: BUG: soft lockup - CPU#3 stuck for 23s! [swapper/0:1]
...
Call Trace:
ptdump_walk_pgd_level_core+0x40c/0x550
ptdump_walk_pgd_level_checkwx+0x17/0x20
mark_rodata_ro+0x13b/0x150
kernel_init+0x2f/0x120
ret_from_fork+0x2c/0x40
I guess that this issue might arise even without KASAN on a huge
machines with several terabytes of RAM.
Stick cond_resched() in pgd loop to fix this.
Reported-by: Tobias Regnery <tobias.regn...@gmail.com>
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
Cc: <sta...@vger.kernel.org>
---
arch/x86/mm/dump_pagetables.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ea9c49a..8aa6bea 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -15,6 +15,7 @@
#include <linux/debugfs.h>
#include <linux/mm.h>
#include <linux/init.h>
+#include <linux/sched.h>
#include <linux/seq_file.h>
#include <asm/pgtable.h>
@@ -406,6 +407,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m,
pgd_t *pgd,
} else
note_page(m, &st, __pgprot(0), 1);
+ cond_resched();
start++;
}
--
2.10.2
