Here's an updated version of the patch that better handles pathological
e820 tables.
On 4/4/25 11:56, msizanoen wrote:
Also, can you reproduce this issue with a target kernel (the kernel
being kexec-ed) that has one of the patches attached (select the
correct one according to your kernel version) applied, with either
kexec_load or kexec_file_load?
On 4/4/25 09:54, msizanoen wrote:
Can you send the dmesg logs for this case (6.13 + mentioned patch
series backported as target kernel, using kexec_load)?
On 4/4/25 05:00, Roberto Ricci wrote:
On 2025-04-01 19:59 +0700, msizanoen wrote:
[snip]
It seems like `e820__register_nosave_regions` is erroneously
marking some
kernel memory as nosave in the presence of sub-page e820 regions.
In theory
backporting
https://lore.kernel.org/all/[email protected]/
should
be sufficient to avoid this but a fix for the actual root cause is
preferred.
When using kexec_file_load, this patch series fixes the issue not only
in theory but also in practice.
But the issue with kexec_load (see
https://lore.kernel.org/all/Z-hYWc9LtBU1Yhtg@desktop0a/
), which might be related, is not fixed.
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 4893d30ce438..5d963df63b7a 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -754,22 +754,21 @@ void __init e820__memory_setup_extended(u64 phys_addr, u32 data_len)
void __init e820__register_nosave_regions(unsigned long limit_pfn)
{
int i;
- unsigned long pfn = 0;
+ u64 last_addr = 0;
for (i = 0; i < e820_table->nr_entries; i++) {
struct e820_entry *entry = &e820_table->entries[i];
- if (pfn < PFN_UP(entry->addr))
- register_nosave_region(pfn, PFN_UP(entry->addr));
-
- pfn = PFN_DOWN(entry->addr + entry->size);
-
if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN)
- register_nosave_region(PFN_UP(entry->addr), pfn);
+ continue;
- if (pfn >= limit_pfn)
- break;
+ if (last_addr < entry->addr)
+ register_nosave_region(PFN_UP(last_addr), PFN_DOWN(entry->addr));
+
+ last_addr = entry->addr + entry->size;
}
+
+ register_nosave_region(PFN_UP(last_addr), limit_pfn);
}
#ifdef CONFIG_ACPI
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 57120f0749cc..656ed7abd28d 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -753,22 +753,21 @@ void __init e820__memory_setup_extended(u64 phys_addr, u32 data_len)
void __init e820__register_nosave_regions(unsigned long limit_pfn)
{
int i;
- unsigned long pfn = 0;
+ u64 last_addr = 0;
for (i = 0; i < e820_table->nr_entries; i++) {
struct e820_entry *entry = &e820_table->entries[i];
- if (pfn < PFN_UP(entry->addr))
- register_nosave_region(pfn, PFN_UP(entry->addr));
-
- pfn = PFN_DOWN(entry->addr + entry->size);
-
if (entry->type != E820_TYPE_RAM)
- register_nosave_region(PFN_UP(entry->addr), pfn);
+ continue;
- if (pfn >= limit_pfn)
- break;
+ if (last_addr < entry->addr)
+ register_nosave_region(PFN_UP(last_addr), PFN_DOWN(entry->addr));
+
+ last_addr = entry->addr + entry->size;
}
+
+ register_nosave_region(PFN_UP(last_addr), limit_pfn);
}
#ifdef CONFIG_ACPI
