Sorry for not replying to you in time
在 2023/6/15 00:07, Mike Rapoport 写道:
Hi,
On Wed, Jun 14, 2023 at 09:17:46PM +0800, Song Shuai wrote:
The memblock APIs are always correct, thus the callers usually don't
handle the return code. But the failure caused by unready memblock_can_resize
is hard to recognize without the return code. Like this piece of log:
Please make it clear that failure is in memblock_double_array(), e.g.
Having numerous memblock reservations at early boot where
memblock_can_resize is unset
may exhaust the INIT_MEMBLOCK_REGIONS sized memblock.reserved regions
and try to
double the region array via memblock_double_array() which fails and
returns -1 to the caller.
You can find the numerous memblock reservations reported by this commit
24cc61d8cb5a ("arm64: memblock: don't permit memblock resizing until
linear mapping is up").
And the similar test sense can be simulated by a constructed dtb with
numerous discrete
/memreserve/ or /reserved-memory regions.
But when memblock_double_array() is called before memblock_can_resize
is true, it is hard to understand the actual reason for the failure.
```
[ 0.000000] memblock_phys_alloc_range: 4096 bytes align=0x1000 from=0x0000000000000000 max_addr=0x0000000000000000 alloc_pmd_fixmap+0x14/0x1c
[ 0.000000] memblock_reserve: [0x000000017ffff000-0x000000017fffffff] memblock_alloc_range_nid+0xb8/0x128
[ 0.000000] Oops - store (or AMO) access fault [#1]
```
So add an error message for this kind of failure:
```
[ 0.000000] memblock_phys_alloc_range: 4096 bytes align=0x1000 from=0x0000000000000000 max_addr=0x0000000000000000 alloc_pmd_fixmap+0x14/0x1c
[ 0.000000] memblock_reserve: [0x000000017ffff000-0x000000017fffffff] memblock_alloc_range_nid+0xb8/0x128
[ 0.000000] memblock: Can't double reserved array for area start 0x000000017ffff000 size 4096
[ 0.000000] Oops - store (or AMO) access fault [#1]
```
Signed-off-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
---
mm/memblock.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/memblock.c b/mm/memblock.c
index 3feafea06ab2..ab952a164f62 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -418,8 +418,11 @@ static int __init_memblock memblock_double_array(struct memblock_type *type,
/* We don't allow resizing until we know about the reserved regions
* of memory that aren't suitable for allocation
*/
- if (!memblock_can_resize)
+ if (!memblock_can_resize) {
+ pr_err("memblock: Can't double %s array for area start %pa size %ld\n",
+ type->name, &new_area_start, (unsigned long)new_area_size);
Most of the time memblock uses %llu and cast to u64 to print size, please
make this consistent.
I will fix it in next version if the above description is ok for you.
return -1;
+ }
/* Calculate new doubled size */
old_size = type->max * sizeof(struct memblock_region);
--
2.20.1
--
Thanks
Song Shuai
