On Tue 15-09-20 11:41:42, Laurent Dufour wrote:
In register_mem_sect_under_node() the system_state’s value is checked to detect whether the call is made during boot time or during an hot-plug operation. Unfortunately, that check against SYSTEM_BOOTING is wrong because regular memory is registered at SYSTEM_SCHEDULING state. In addition, memory hot-plug operation can be triggered at this system state by the ACPI [1]. So checking against the system state is not enough.
The consequence is that on system with interleaved node's ranges like this: Early memory node ranges node 1: [mem 0x0000000000000000-0x000000011fffffff] node 2: [mem 0x0000000120000000-0x000000014fffffff] node 1: [mem 0x0000000150000000-0x00000001ffffffff] node 0: [mem 0x0000000200000000-0x000000048fffffff] node 2: [mem 0x0000000490000000-0x00000007ffffffff]
This can be seen on PowerPC LPAR after multiple memory hot-plug and hot-unplug operations are done. At the next reboot the node's memory ranges can be interleaved and since the call to link_mem_sections() is made in topology_init() while the system is in the SYSTEM_SCHEDULING state, the node's id is not checked, and the sections registered to multiple nodes:
$ ls -l /sys/devices/system/memory/memory21/node* total 0 lrwxrwxrwx 1 root root 0 Aug 24 05:27 node1 -> ../../node/node1 lrwxrwxrwx 1 root root 0 Aug 24 05:27 node2 -> ../../node/node2
In that case, the system is able to boot but if later one of theses memory blocks is hot-unplugged and then hot-plugged, the sysfs inconsistency is detected and this is triggering a BUG_ON():
------------[ cut here ]------------ kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4 CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25 NIP: c000000000403f34 LR: c000000000403f2c CTR: 0000000000000000 REGS: c0000004876e3660 TRAP: 0700 Not tainted (5.9.0-rc1+) MSR: 800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24000448 XER: 20040000 CFAR: c000000000846d20 IRQMASK: 0 GPR00: c000000000403f2c c0000004876e38f0 c0000000012f6f00 ffffffffffffffef GPR04: 0000000000000227 c0000004805ae680 0000000000000000 00000004886f0000 GPR08: 0000000000000226 0000000000000003 0000000000000002 fffffffffffffffd GPR12: 0000000088000484 c00000001ec96280 0000000000000000 0000000000000000 GPR16: 0000000000000000 0000000000000000 0000000000000004 0000000000000003 GPR20: c00000047814ffe0 c0000007ffff7c08 0000000000000010 c0000000013332c8 GPR24: 0000000000000000 c0000000011f6cc0 0000000000000000 0000000000000000 GPR28: ffffffffffffffef 0000000000000001 0000000150000000 0000000010000000 NIP [c000000000403f34] add_memory_resource+0x244/0x340 LR [c000000000403f2c] add_memory_resource+0x23c/0x340 Call Trace: [c0000004876e38f0] [c000000000403f2c] add_memory_resource+0x23c/0x340 (unreliable) [c0000004876e39c0] [c00000000040408c] __add_memory+0x5c/0xf0 [c0000004876e39f0] [c0000000000e2b94] dlpar_add_lmb+0x1b4/0x500 [c0000004876e3ad0] [c0000000000e3888] dlpar_memory+0x1f8/0xb80 [c0000004876e3b60] [c0000000000dc0d0] handle_dlpar_errorlog+0xc0/0x190 [c0000004876e3bd0] [c0000000000dc398] dlpar_store+0x198/0x4a0 [c0000004876e3c90] [c00000000072e630] kobj_attr_store+0x30/0x50 [c0000004876e3cb0] [c00000000051f954] sysfs_kf_write+0x64/0x90 [c0000004876e3cd0] [c00000000051ee40] kernfs_fop_write+0x1b0/0x290 [c0000004876e3d20] [c000000000438dd8] vfs_write+0xe8/0x290 [c0000004876e3d70] [c0000000004391ac] ksys_write+0xdc/0x130 [c0000004876e3dc0] [c000000000034e40] system_call_exception+0x160/0x270 [c0000004876e3e20] [c00000000000d740] system_call_common+0xf0/0x27c Instruction dump: 48442e35 60000000 0b030000 3cbe0001 7fa3eb78 7bc48402 38a5fffe 7ca5fa14 78a58402 48442db1 60000000 7c7c1b78 <0b030000> 7f23cb78 4bda371d 60000000 ---[ end trace 562fd6c109cd0fb2 ]---
This patch addresses the root cause by not relying on the system_state value to detect whether the call is due to a hot-plug operation. An extra parameter is added to link_mem_sections() detailing whether the operation is due to a hot-plug operation.
[1] According to Oscar Salvador, using this qemu command line, ACPI memory hotplug operations are raised at SYSTEM_SCHEDULING state:
$QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \ -m size=$MEM,slots=255,maxmem=4294967296k \ -numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \ -object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \ -object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \ -object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \ -object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \ -object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \ -object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \ -object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
Fixes: 4fbce633910e ("mm/memory_hotplug.c: make register_mem_sect_under_node() a callback of walk_memory_range()") Signed-off-by: Laurent Dufour ldufour@linux.ibm.com Reviewed-by: David Hildenbrand david@redhat.com Cc: stable@vger.kernel.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: "Rafael J. Wysocki" rafael@kernel.org Cc: Andrew Morton akpm@linux-foundation.org Cc: Michal Hocko mhocko@suse.com Cc: Oscar Salvador osalvador@suse.de
Acked-by: Michal Hocko mhocko@suse.com
drivers/base/node.c | 85 ++++++++++++++++++++++++++++---------------- include/linux/node.h | 11 +++--- mm/memory_hotplug.c | 3 +- 3 files changed, 64 insertions(+), 35 deletions(-)
diff --git a/drivers/base/node.c b/drivers/base/node.c index 508b80f6329b..50af16e68d98 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -761,14 +761,36 @@ static int __ref get_nid_for_pfn(unsigned long pfn) return pfn_to_nid(pfn); } +static int do_register_memory_block_under_node(int nid,
struct memory_block *mem_blk)+{
- int ret;
- /*
* If this memory block spans multiple nodes, we only indicate* the last processed node.*/- mem_blk->nid = nid;
- ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
&mem_blk->dev.kobj,kobject_name(&mem_blk->dev.kobj));- if (ret)
return ret;- return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
&node_devices[nid]->dev.kobj,kobject_name(&node_devices[nid]->dev.kobj));+}
/* register memory section under specified node if it spans that node */ -static int register_mem_sect_under_node(struct memory_block *mem_blk,
void *arg)+static int register_mem_block_under_node_early(struct memory_block *mem_blk,
void *arg){ unsigned long memory_block_pfns = memory_block_size_bytes() / PAGE_SIZE; unsigned long start_pfn = section_nr_to_pfn(mem_blk->start_section_nr); unsigned long end_pfn = start_pfn + memory_block_pfns - 1;
- int ret, nid = *(int *)arg;
- int nid = *(int *)arg; unsigned long pfn;
for (pfn = start_pfn; pfn <= end_pfn; pfn++) { @@ -785,38 +807,33 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk, } /*
* We need to check if page belongs to nid only for the boot* case, during hotplug we know that all pages in the memory* block belong to the same node.*/if (system_state == SYSTEM_BOOTING) {page_nid = get_nid_for_pfn(pfn);if (page_nid < 0)continue;if (page_nid != nid)continue;}/** If this memory block spans multiple nodes, we only indicate* the last processed node.
* We need to check if page belongs to nid only at the boot* case because node's ranges can be interleaved.
mem_blk->nid = nid;ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,&mem_blk->dev.kobj,kobject_name(&mem_blk->dev.kobj));if (ret)return ret;
page_nid = get_nid_for_pfn(pfn);if (page_nid < 0)continue;if (page_nid != nid)continue;
return sysfs_create_link_nowarn(&mem_blk->dev.kobj,&node_devices[nid]->dev.kobj,kobject_name(&node_devices[nid]->dev.kobj));
return do_register_memory_block_under_node(nid, mem_blk);} +/*
- During hotplug we know that all pages in the memory block belong to the same
- node.
- */
+static int register_mem_block_under_node_hotplug(struct memory_block *mem_blk,
void *arg)+{
- int nid = *(int *)arg;
- return do_register_memory_block_under_node(nid, mem_blk);
+}
/*
- Unregister a memory block device under the node it spans. Memory blocks
- with multiple nodes cannot be offlined and therefore also never be removed.
@@ -832,11 +849,19 @@ void unregister_memory_block_under_nodes(struct memory_block *mem_blk) kobject_name(&node_devices[mem_blk->nid]->dev.kobj)); } -int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn) +int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn,
enum meminit_context context){
- walk_memory_blocks_func_t func;
- if (context == MEMINIT_HOTPLUG)
func = register_mem_block_under_node_hotplug;- else
func = register_mem_block_under_node_early;- return walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn), (void *)&nid,
register_mem_sect_under_node);
func);} #ifdef CONFIG_HUGETLBFS diff --git a/include/linux/node.h b/include/linux/node.h index 4866f32a02d8..014ba3ab2efd 100644 --- a/include/linux/node.h +++ b/include/linux/node.h @@ -99,11 +99,13 @@ extern struct node *node_devices[]; typedef void (*node_registration_func_t)(struct node *); #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA) -extern int link_mem_sections(int nid, unsigned long start_pfn,
unsigned long end_pfn);+int link_mem_sections(int nid, unsigned long start_pfn,
unsigned long end_pfn,enum meminit_context context);#else static inline int link_mem_sections(int nid, unsigned long start_pfn,
unsigned long end_pfn)
unsigned long end_pfn,enum meminit_context context){ return 0; } @@ -128,7 +130,8 @@ static inline int register_one_node(int nid) if (error) return error; /* link memory sections under this node */
error = link_mem_sections(nid, start_pfn, end_pfn);
error = link_mem_sections(nid, start_pfn, end_pfn,MEMINIT_EARLY);return error; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index fc25886ad719..03df20078827 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1080,7 +1080,8 @@ int __ref add_memory_resource(int nid, struct resource *res) } /* link memory sections under this node.*/
- ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1));
- ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
MEMINIT_HOTPLUG);/* create new memmap entry */ -- 2.28.0