[PATCH 1/4] vmcoreinfo: increase vmcoreinfo buffer to 8KB

[Pnina Feder]

Additional metadata will be exported to vmcoreinfo, requiring more
buffer space than a single 4KB page provides.

Change VMCOREINFO_BYTES from PAGE_SIZE to a fixed SZ_8K. This
decouples the buffer size from the page size, avoiding waste on
architectures with large pages (e.g. 16KB on MIPS, 64KB on arm64)
while providing enough space on 4KB-page architectures like RISC-V.

The existing allocation in kimage_crash_copy_vmcoreinfo() already
uses get_order() and DIV_ROUND_UP(), so it correctly rounds up to
whole pages regardless of the constant's value.

Signed-off-by: Pnina Feder <pnina.feder@xxxxxxxxxxxx>
---
 include/linux/vmcore_info.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/vmcore_info.h b/include/linux/vmcore_info.h
index e71518caacdf..612dcf7b9ecd 100644
--- a/include/linux/vmcore_info.h
+++ b/include/linux/vmcore_info.h
@@ -20,7 +20,8 @@
 				     CRASH_CORE_NOTE_NAME_BYTES +	\
 				     CRASH_CORE_NOTE_DESC_BYTES)
 
-#define VMCOREINFO_BYTES	   PAGE_SIZE
+/* Fixed size independent of PAGE_SIZE to avoid waste on large-page archs */
+#define VMCOREINFO_BYTES	   SZ_8K
 #define VMCOREINFO_NOTE_NAME	   "VMCOREINFO"
 #define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
 #define VMCOREINFO_NOTE_SIZE	   ((CRASH_CORE_NOTE_HEAD_BYTES * 2) +	\
-- 
2.43.0