LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	<x86@kernel.org>
Cc: Tobias Regnery <tobias.regnery@gmail.com>,
	"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Alexander Potapenko <glider@google.com>,
	<kasan-dev@googlegroups.com>, <linux-kernel@vger.kernel.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	<stable@vger.kernel.org>
Subject: [PATCH] x86/mm/ptdump: Fix soft lockup in page table walker.
Date: Fri, 10 Feb 2017 12:54:05 +0300
Message-ID: <20170210095405.31802-1-aryabinin@virtuozzo.com> (raw)
In-Reply-To: <0d19ac08-88b0-675d-19bd-4cdc543fdb30@virtuozzo.com>

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.regnery@gmail.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@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

  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-09 12:46 BUG: soft lockup in 4.10-rc7 with KASAN enabled Tobias Regnery
2017-02-09 16:46 ` Paul E. McKenney
2017-02-09 16:56   ` Paul E. McKenney
2017-02-09 17:23     ` Dmitry Vyukov
2017-02-10  8:14       ` Tobias Regnery
2017-02-10  9:47 ` Andrey Ryabinin
2017-02-10  9:54   ` Andrey Ryabinin [this message]
2017-02-10 10:07     ` [tip:x86/urgent] x86/mm/ptdump: Fix soft lockup in page table walker tip-bot for Andrey Ryabinin
2017-02-10 10:24     ` [PATCH] " Dmitry Vyukov
2017-02-10 11:18       ` Thomas Gleixner
2017-02-10 12:15         ` Andrey Ryabinin
2017-02-10 13:02           ` Dmitry Vyukov
2017-02-10 13:56             ` Andrey Ryabinin
2017-02-10 14:17               ` Dmitry Vyukov
2017-02-10 14:29               ` Mark Rutland
2017-02-10 14:38                 ` Andrey Ryabinin
2017-02-10 14:41                   ` Mark Rutland
2017-02-10 14:38             ` Mark Rutland

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170210095405.31802-1-aryabinin@virtuozzo.com \
    --to=aryabinin@virtuozzo.com \
    --cc=dvyukov@google.com \
    --cc=glider@google.com \
    --cc=hpa@zytor.com \
    --cc=kasan-dev@googlegroups.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=stable@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tobias.regnery@gmail.com \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git