On 17.10.24 09:36, Alexander Gordeev wrote:
On Mon, Oct 14, 2024 at 04:46:16PM +0200, David Hildenbrand wrote:
Hi David!
Hi Alexander!
@@ -157,7 +189,9 @@ unsigned long detect_max_physmem_end(void)
{
unsigned long max_physmem_end = 0;
- if (!sclp_early_get_memsize(&max_physmem_end)) {
+ if (!diag500_storage_limit(&max_physmem_end)) {
+ physmem_info.info_source = MEM_DETECT_DIAG500_STOR_LIMIT;
+ } else if (!sclp_early_get_memsize(&max_physmem_end)) {
physmem_info.info_source = MEM_DETECT_SCLP_READ_INFO;
} else {
max_physmem_end = search_mem_end();
@@ -170,11 +204,17 @@ void detect_physmem_online_ranges(unsigned long max_physmem_end)
{
if (!sclp_early_read_storage_info()) {
physmem_info.info_source = MEM_DETECT_SCLP_STOR_INFO;
+ return;
} else if (!diag260()) {
physmem_info.info_source = MEM_DETECT_DIAG260;
- } else if (max_physmem_end) {
- add_physmem_online_range(0, max_physmem_end);
+ return;
+ } else if (physmem_info.info_source == MEM_DETECT_DIAG500_STOR_LIMIT) {
+ max_physmem_end = 0;
+ if (!sclp_early_get_memsize(&max_physmem_end))
+ physmem_info.info_source = MEM_DETECT_SCLP_READ_INFO;
Why search_mem_end() is not tried in case sclp_early_get_memsize() failed?
Patch #3 documents that:
+ The storage limit does not indicate currently usable storage, it may
+ include holes, standby storage and areas reserved for other means, such
+ as memory hotplug or virtio-mem devices. Other interfaces for detecting
+ actually usable storage, such as SCLP, must be used in conjunction with
+ this subfunction.
If SCLP would fail, something would be seriously wrong and we should just crash
instead of trying to fallback to the legacy way of scanning.
}
+ if (max_physmem_end)
+ add_physmem_online_range(0, max_physmem_end);
}
void physmem_set_usable_limit(unsigned long limit)
diff --git a/arch/s390/include/asm/physmem_info.h b/arch/s390/include/asm/physmem_info.h
index f45cfc8bc233..51b68a43e195 100644
--- a/arch/s390/include/asm/physmem_info.h
+++ b/arch/s390/include/asm/physmem_info.h
@@ -9,6 +9,7 @@ enum physmem_info_source {
MEM_DETECT_NONE = 0,
MEM_DETECT_SCLP_STOR_INFO,
MEM_DETECT_DIAG260,
+ MEM_DETECT_DIAG500_STOR_LIMIT,
MEM_DETECT_SCLP_READ_INFO,
MEM_DETECT_BIN_SEARCH
};
@@ -107,6 +108,8 @@ static inline const char *get_physmem_info_source(void)
return "sclp storage info";
case MEM_DETECT_DIAG260:
return "diag260";
+ case MEM_DETECT_DIAG500_STOR_LIMIT:
+ return "diag500 storage limit";
AFAIU you want to always override MEM_DETECT_DIAG500_STOR_LIMIT method
with an online memory detection method. In that case this code is dead.
Not in the above case, pathological case above where something went wrong
during sclp_early_get_memsize(). In that scenario, die_oom() would indicate
that there are no memory ranges but that "diag500 storage limit" worked.
Does that make sense?
Thanks for the review!
--
Cheers,
David / dhildenb
