Messages in this thread | | | From | Chao Fan <> | Subject | [PATCH 0/4] kaslr: extend movable_node to movable_node=nn[KMG]@ss[KMG] | Date | Thu, 19 Oct 2017 18:02:39 +0800 |
| |
Here is a problem: Here is a machine with several NUMA nodes and some of them are hot-pluggable. It's not good for kernel to be extracted in the memory region of movable node. But in current code, I print the address choosen by kaslr and found it may be placed in movable node sometimes. To solve this problem, it's better to limit the memory region choosen by kaslr to immovable node in kaslr.c. But the memory infomation about if it's hot-pluggable is stored in ACPI SRAT table, which is parsed after kernel is extracted. So we can't get the detail memory infomation before extracting kernel.
So extend the movable_node to movable_node=nn@ss, in which nn means the size of memory in *immovable* node, and ss means the start position of this memory region. Then limit kaslr choose memory in these regions.
There are two policies: 1. Specify the memory region in *movable* node to avoid: Then we can use the existing mem_avoid to handle. But if the memory one movable node was separated by memory hole or different movable nodes are discontinuous, we don't know how many regions need to avoid. OTOH, we must avoid all of the movable memory, otherwise, kaslr may choose the wrong place. 2. Specify the memory region in "immovable* node to select: Only support 4 regions in this parameter. Then user can use two nodes at least for kaslr to choose, it's enough for the kernel to extract. At the same time, because we need only 4 new mem_vector, the usage of memory here is not too big.
PATCH 1/4 parse the extended movable_node=nn[KMG]@ss[KMG], then store the memory regions. PATCH 2/4 selects the memory region in immovable node when process memmap. PATCH 3/4 is the change of document. PATCH 4/4 cleans up some little problems.
Chao Fan (4): kaslr: parse the extended movable_node=nn[KMG]@ss[KMG] kaslr: select the memory region in immovable node to process document: change the document for the extended movable_node kaslr: clean up a useless variable and some usless space
Documentation/admin-guide/kernel-parameters.txt | 9 ++ arch/x86/boot/compressed/kaslr.c | 140 +++++++++++++++++++++--- 2 files changed, 131 insertions(+), 18 deletions(-)
-- 2.13.6
| |