From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:48262 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751756AbdBLWPe (ORCPT ); Sun, 12 Feb 2017 17:15:34 -0500 Subject: Patch "x86/mm/ptdump: Fix soft lockup in page table walker" has been added to the 4.9-stable tree To: aryabinin@virtuozzo.com, dvyukov@google.com, glider@google.com, gregkh@linuxfoundation.org, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, tobias.regnery@gmail.com Cc: , From: Date: Sun, 12 Feb 2017 14:15:30 -0800 Message-ID: <148693773051149@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled x86/mm/ptdump: Fix soft lockup in page table walker to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-mm-ptdump-fix-soft-lockup-in-page-table-walker.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 146fbb766934dc003fcbf755b519acef683576bf Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Fri, 10 Feb 2017 12:54:05 +0300 Subject: x86/mm/ptdump: Fix soft lockup in page table walker From: Andrey Ryabinin commit 146fbb766934dc003fcbf755b519acef683576bf upstream. 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 Signed-off-by: Andrey Ryabinin Cc: kasan-dev@googlegroups.com Cc: Alexander Potapenko Cc: "Paul E . McKenney" Cc: Dmitry Vyukov Link: http://lkml.kernel.org/r/20170210095405.31802-1-aryabinin@virtuozzo.com Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/dump_pagetables.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -406,6 +407,7 @@ static void ptdump_walk_pgd_level_core(s } else note_page(m, &st, __pgprot(0), 1); + cond_resched(); start++; } Patches currently in stable-queue which might be from aryabinin@virtuozzo.com are queue-4.9/x86-mm-ptdump-fix-soft-lockup-in-page-table-walker.patch queue-4.9/drm-i915-fix-use-after-free-in-page_flip_completed.patch