From: Chao Fan <fanc.fnst@cn.fujitsu.com>
To: <linux-kernel@vger.kernel.org>, <x86@kernel.org>,
<yasu.isimatu@gmail.com>, <keescook@chromium.org>
Cc: <indou.takao@jp.fujitsu.com>, <bhe@redhat.com>,
<caoj.fnst@cn.fujitsu.com>, <douly.fnst@cn.fujitsu.com>,
<fanc.fnst@cn.fujitsu.com>
Subject: Bug report about KASLR and ZONE_MOVABLE
Date: Wed, 11 Jul 2018 17:42:44 +0800 [thread overview]
Message-ID: <20180711094244.GA2019@localhost.localdomain> (raw)
Hi all,
I found there is a BUG about KASLR and ZONE_MOVABLE.
When users use 'kernelcore=' parameter without 'movable_node',
movable memory is evenly distributed to all nodes. The size of
ZONE_MOVABLE depends on the kernel parameter 'kernelcore=' and
'movablecore='.
But sometiomes, KASLR may put the uncompressed kernel to the
tail position of a node, which will cause the kernel memory
set as ZONE_MOVABLE. This region can not be offlined.
Here is a very simple test in my qemu-kvm machine, there is
only one node:
The command line:
[root@localhost ~]# cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-4.18.0-rc3+ root=/dev/mapper/fedora_localhost--live-root
ro resume=/dev/mapper/fedora_localhost--live-swap
rd.lvm.lv=fedora_localhost-live/root rd.lvm.lv=fedora_localhost-live/swap
console=ttyS0 earlyprintk=ttyS0,115200n8 memblock=debug kernelcore=50%
I use 'kernelcore=50%' here.
Here is my early print result, I print the random_addr after KASLR chooses
physical memory:
early console in extract_kernel
input_data: 0x000000000266b3b1
input_len: 0x00000000007d8802
output: 0x0000000001000000
output_len: 0x0000000001e15698
kernel_total_size: 0x0000000001a8b000
trampoline_32bit: 0x000000000009d000
booted via startup_32()
Physical KASLR using RDRAND RDTSC...
random_addr: 0x000000012f000000
Virtual KASLR using RDRAND RDTSC...
The address for kernel is 0x000000012f000000
Here is the log of ZONE:
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x0000000000001000-0x0000000000ffffff]
[ 0.000000] DMA32 [mem 0x0000000001000000-0x00000000ffffffff]
[ 0.000000] Normal [mem 0x0000000100000000-0x00000001f57fffff]
[ 0.000000] Device empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Node 0: 0x000000011b000000
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000001000-0x000000000009efff]
[ 0.000000] node 0: [mem 0x0000000000100000-0x00000000bffd6fff]
[ 0.000000] node 0: [mem 0x0000000100000000-0x00000001f57fffff]
[ 0.000000] Initmem setup node 0 [mem
0x0000000000001000-0x00000001f57fffff]
Only one node in my machine, ZONE_MOVABLE begins from 0x000000011b000000,
which is lower than 0x000000012f000000.
So KASLR put the kernel to the ZONE_MOVABLE.
Try to solve this problem, I think there should be a new tactic in function
find_zone_movable_pfns_for_nodes() of mm/page_alloc.c. If kernel is uncompressed
in a tail position, then just set the memory after the kernel as ZONE_MOVABLE,
at the same time, memory in other nodes will be set as ZONE_MOVABLE.
If there is something wrong, pleas let me know. And any comments will be welcome.
Thanks,
Chao Fan
next reply other threads:[~2018-07-11 9:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 9:42 Chao Fan [this message]
2018-07-11 10:04 ` Bug report about KASLR and ZONE_MOVABLE Chao Fan
2018-07-11 10:16 ` Chao Fan
2018-07-11 10:41 ` Baoquan He
2018-07-11 10:49 ` Baoquan He
2018-07-11 12:40 ` Baoquan He
2018-07-11 17:59 ` [PATCH v3] mm, page_alloc: find movable zone after kernel text kbuild test robot
2018-07-11 19:02 ` kbuild test robot
2018-07-12 1:19 ` Bug report about KASLR and ZONE_MOVABLE Chao Fan
2018-07-12 12:08 ` Baoquan He
2018-07-12 5:49 ` Dou Liyang
2018-07-12 6:01 ` Chao Fan
2018-07-12 12:32 ` Michal Hocko
2018-07-12 23:52 ` Baoquan He
2018-07-13 1:44 ` Chao Fan
2018-07-16 11:38 ` Michal Hocko
2018-07-16 13:02 ` Baoquan He
2018-07-16 15:24 ` Michal Hocko
2018-07-17 1:51 ` Baoquan He
2018-07-17 8:22 ` Michal Hocko
2018-07-11 12:41 ` Baoquan He
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