Hi mm folks,
Just a quick question, what is the expected behavior of memblock_reserve
a region that is not added to memblock with memblock_add?
I'm unable to find any documentation about memblock_reserve in comments and
boot-time-mm, but as per my understanding to the code, this should be a
legit usage?
In practical we run into uninitialized nid of reserved block problem,
should we fix it
in our usage, or on memblock side?
Thanks
在 2023/12/25 09:30, Huang Pei 写道:
Since commit 61167ad5fecd("mm: pass nid to reserve_bootmem_region()),
loongson64 booting failed with CONFIG_DEFERRED_STRUCT_PAGE_INIT like
this:
----------------------------------------------------------------------
Call Trace:
[<ffffffff8235d088>] reserve_bootmem_region+0xa8/0x184
[<ffffffff82333940>] memblock_free_all+0x104/0x2a8
[<ffffffff8231d8e4>] mem_init+0x84/0x94
[<ffffffff82330958>] mm_core_init+0xf8/0x308
[<ffffffff82318c38>] start_kernel+0x43c/0x86c
Code: 10400028 2402fff0 de420000 <dc432880> 0203182b 14600022
64420070 00003025 24040003
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Attempted to kill the idle task!
---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---
----------------------------------------------------------------------
The root cause is no memory region "0x0-0x1fffff" paired with
memory-reserved region "0x0-0x1fffff" and "0x0-0xfff", with "memblock
=debug":
----------------------------------------------------------------------
memory[0x0] [0x0000000000200000-0x000000000effffff],
0x000000000ee00000 bytes on node 0 flags: 0x0 !!!!here
memory[0x1] [0x0000000090000000-0x00000000fdffffff],
0x000000006e000000 bytes on node 0 flags: 0x0
memory[0x2] [0x0000000100000000-0x000000027fffffff],
0x0000000180000000 bytes on node 0 flags: 0x0
memory[0x3] [0x0000100000000000-0x000010000fffffff],
0x0000000010000000 bytes on node 1 flags: 0x0
memory[0x4] [0x0000100090000000-0x000010027fffffff],
0x00000001f0000000 bytes on node 1 flags: 0x0
reserved.cnt = 0x1f
reserved[0x0] [0x0000000000000000-0x000000000190c80a],
0x000000000190c80b bytes flags: 0x0 !!!!oops 0x0-0x1fffff not in memory[0]
reserved[0x1] [0x000000000190c810-0x000000000190eea3],
0x0000000000002694 bytes flags: 0x0
----------------------------------------------------------------------
It caused memory-reserved region "0x0-0x1fffff" without valid node id
in "memblock_get_region_node" from "memmap_init_reserved_pages", lead to
"reserve_bootmem_region-> init_reserved_page -> early_pfn_to_nid()"
accessing "node_data" out of bound.
To fix this bug, we should remove unnecessary memory block reservation.
+. no need to reserve 0x0-0x1fffff below kernel loading address, since
it is not registered by "memblock_add_node"
+. no need to reserve 0x0-0xfff for exception handling if it is not
registered by "memblock_add" either.
Fixes: commit 61167ad5fecd("mm: pass nid to reserve_bootmem_region())
Signed-off-by: Huang Pei <huangpei@xxxxxxxxxxx>
---
arch/mips/kernel/traps.c | 3 ++-
arch/mips/loongson64/numa.c | 2 --
2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 246c6a6b0261..9b632b4c10c3 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -2007,7 +2007,8 @@ unsigned long vi_handlers[64];
void reserve_exception_space(phys_addr_t addr, unsigned long size)
{
- memblock_reserve(addr, size);
+ if(memblock_is_region_memory(addr, size))
+ memblock_reserve(addr, size);
}
void __init *set_except_vector(int n, void *addr)
diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
index 8f61e93c0c5b..0f516dde81da 100644
--- a/arch/mips/loongson64/numa.c
+++ b/arch/mips/loongson64/numa.c
@@ -130,8 +130,6 @@ static void __init node_mem_init(unsigned int node)
memblock_reserve((node_addrspace_offset | 0xfe000000),
32 << 20);
- /* Reserve pfn range 0~node[0]->node_start_pfn */
- memblock_reserve(0, PAGE_SIZE * start_pfn);
}
}
--
---
Jiaxun Yang
