Re: [memcg BUG] unable to handle kernel NULL pointer derefence at00000000

亀澤 寛之
2008-10-21T13:44:09Z

> KAMEZAWA Hiroyuki wrote:
>> On Tue, 21 Oct 2008 17:44:40 +0530
>> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>>>> I got an idea and maybe can send a patch soon. I'm now finding x86-32
>>>> box..
>>> Please send it to me, I am able to reproduce the problem with my kvm
>>> setup on my
>>> 32 bit system. I can do a quick test/verification for you.
>>>
>> Thanks. how about this ? test on x86-64 is done.
>> -Kame
>> ==
>>
>>
>>
>> page_cgroup_init() is called from mem_cgroup_init(). But at this
>> point, we cannot call alloc_bootmem().
>> (and this caused panic at boot.)
>>
>> This patch moves page_cgroup_init() to init/main.c.
>>
>> Time table is following:
>> ==
>> parse_args(). # we can trust mem_cgroup_subsys.disabled bit after
>> this.
>> ....
>> cgroup_init_early() # "early" init of cgroup.
>> ....
>> setup_arch() # memmap is allocated.
>> ...
>> page_cgroup_init();
>> mem_init(); # we cannot call alloc_bootmem after this.
>> ....
>> cgroup_init() # mem_cgroup is initialized.
>> ==
>>
>> Before page_cgroup_init(), mem_map must be initialized. So,
>> I added page_cgroup_init() to init/main.c directly.
>>
>> (*) maybe this is not very clean but cgroup_init_early() is too early
>> and we have to use vmalloc instead of alloc_bootmem() in
>> cgroup_init().
>> usage of vmalloc area in x86-32 is important and we should avoid
>> vmalloc() in x86-32. So, we want to use alloc_bootmem() from
>> sutaible place.
>>
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>
>> include/linux/page_cgroup.h | 1 +
>> init/main.c | 2 ++
>> mm/memcontrol.c | 1 -
>> mm/page_cgroup.c | 35 ++++++++++++++++++++++++++++-------
>> 4 files changed, 31 insertions(+), 8 deletions(-)
>>
>> Index: linux-2.6/init/main.c
>> ===================================================================
>> --- linux-2.6.orig/init/main.c
>> +++ linux-2.6/init/main.c
>> @@ -62,6 +62,7 @@
>> #include <linux/signal.h>
>> #include <linux/idr.h>
>> #include <linux/ftrace.h>
>> +#include <linux/page_cgroup.h>
>>
>> #include <asm/io.h>
>> #include <asm/bugs.h>
>> @@ -647,6 +648,7 @@ asmlinkage void __init start_kernel(void
>> vmalloc_init();
>> vfs_caches_init_early();
>> cpuset_init_early();
>> + page_cgroup_init();
>> mem_init();
>> enable_debug_pagealloc();
>> cpu_hotplug_init();
>> Index: linux-2.6/mm/memcontrol.c
>> ===================================================================
>> --- linux-2.6.orig/mm/memcontrol.c
>> +++ linux-2.6/mm/memcontrol.c
>> @@ -1088,7 +1088,6 @@ mem_cgroup_create(struct cgroup_subsys *
>> int node;
>>
>> if (unlikely((cont->parent) == NULL)) {
>> - page_cgroup_init();
>> mem = &init_mem_cgroup;
>> } else {
>> mem = mem_cgroup_alloc();
>> Index: linux-2.6/include/linux/page_cgroup.h
>> ===================================================================
>> --- linux-2.6.orig/include/linux/page_cgroup.h
>> +++ linux-2.6/include/linux/page_cgroup.h
>> @@ -3,6 +3,7 @@
>>
>> #ifdef CONFIG_CGROUP_MEM_RES_CTLR
>> #include <linux/bit_spinlock.h>
>> +
>> /*
>> * Page Cgroup can be considered as an extended mem_map.
>> * A page_cgroup page is associated with every page descriptor. The
>> Index: linux-2.6/mm/page_cgroup.c
>> ===================================================================
>> --- linux-2.6.orig/mm/page_cgroup.c
>> +++ linux-2.6/mm/page_cgroup.c
>> @@ -4,7 +4,12 @@
>> #include <linux/bit_spinlock.h>
>> #include <linux/page_cgroup.h>
>> #include <linux/hash.h>
>> +#include <linux/slab.h>
>> #include <linux/memory.h>
>> +#include <linux/cgroup.h>
>> +
>> +extern struct cgroup_subsys mem_cgroup_subsys;
>> +
>>
>> static void __meminit
>> __init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
>> @@ -66,6 +71,9 @@ void __init page_cgroup_init(void)
>>
>> int nid, fail;
>>
>> + if (mem_cgroup_subsys.disabled)
>> + return;
>> +
>> for_each_online_node(nid) {
>> fail = alloc_node_page_cgroup(nid);
>> if (fail)
>> @@ -106,9 +114,14 @@ int __meminit init_section_page_cgroup(u
>> nid = page_to_nid(pfn_to_page(pfn));
>>
>> table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;
>> - base = kmalloc_node(table_size, GFP_KERNEL, nid);
>> - if (!base)
>> - base = vmalloc_node(table_size, nid);
>> + if (slab_is_available()) {
>> + base = kmalloc_node(table_size, GFP_KERNEL, nid);
>> + if (!base)
>> + base = vmalloc_node(table_size, nid);
>> + } else {
>> + base = __alloc_bootmem_node_nopanic(NODE_DATA(nid), table_size,
>> + PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
>> + }
>>
>> if (!base) {
>> printk(KERN_ERR "page cgroup allocation failure\n");
>> @@ -135,11 +148,16 @@ void __free_page_cgroup(unsigned long pf
>> if (!ms || !ms->page_cgroup)
>> return;
>> base = ms->page_cgroup + pfn;
>> - ms->page_cgroup = NULL;
>> - if (is_vmalloc_addr(base))
>> + if (is_vmalloc_addr(base)) {
>> vfree(base);
>> - else
>> - kfree(base);
>> + ms->page_cgroup = NULL;
>> + } else {
>> + struct page *page = virt_to_page(base);
>> + if (!PageReserved(page)) { /* Is bootmem ? */
>> + kfree(base);
>> + ms->page_cgroup = NULL;
>> + }
>> + }
>> }
>>
>> int online_page_cgroup(unsigned long start_pfn,
>> @@ -213,6 +231,9 @@ void __init page_cgroup_init(void)
>> unsigned long pfn;
>> int fail = 0;
>>
>> + if (mem_cgroup_subsys.disabled)
>> + return;
>> +
>> for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) {
>> if (!pfn_present(pfn))
>> continue;
>
> Booted on x86_32 for me
>
> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> Tested-by: Balbir Singh <balbir@linux.vnet.ibm.com>
>

Thank you ! (I'll resend later if necessary.)

-Kame