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authorAndrey Ryabinin <aryabinin@virtuozzo.com>2017-02-10 12:54:05 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-02-10 11:00:23 +0100
commit146fbb766934dc003fcbf755b519acef683576bf (patch)
treecb8a89a1a93abce2de66d5ded015154aebf3af75
parent5f2e71e71410ecb858cfec184ba092adaca61626 (diff)
x86/mm/ptdump: Fix soft lockup in page table walker
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 huge machines with several terabytes of RAM. Stick cond_resched() in pgd loop to fix this. Reported-by: Tobias Regnery <tobias.regnery@gmail.com> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: kasan-dev@googlegroups.com Cc: Alexander Potapenko <glider@google.com> Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20170210095405.31802-1-aryabinin@virtuozzo.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/mm/dump_pagetables.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ea9c49adaa1f..8aa6bea1cd6c 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++;
}