+ kernel-crash-handle-multi-page-vmcoreinfo-in-crash-kernel-copy.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: kernel/crash: handle multi-page vmcoreinfo in crash kernel copy
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     kernel-crash-handle-multi-page-vmcoreinfo-in-crash-kernel-copy.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kernel-crash-handle-multi-page-vmcoreinfo-in-crash-kernel-copy.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Pnina Feder <pnina.feder@mobileye.com>
Subject: kernel/crash: handle multi-page vmcoreinfo in crash kernel copy
Date: Tue, 16 Dec 2025 15:28:01 +0200

kimage_crash_copy_vmcoreinfo() currently assumes vmcoreinfo fits in a
single page.  This breaks if VMCOREINFO_BYTES exceeds PAGE_SIZE.

Allocate the required order of control pages and vmap all pages needed to
safely copy vmcoreinfo into the crash kernel image.

Link: https://lkml.kernel.org/r/20251216132801.807260-3-pnina.feder@mobileye.com
Signed-off-by: Pnina Feder <pnina.feder@mobileye.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/crash_core.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/kernel/crash_core.c~kernel-crash-handle-multi-page-vmcoreinfo-in-crash-kernel-copy
+++ a/kernel/crash_core.c
@@ -44,9 +44,15 @@ note_buf_t __percpu *crash_notes;
 
 int kimage_crash_copy_vmcoreinfo(struct kimage *image)
 {
-	struct page *vmcoreinfo_page;
+	struct page *vmcoreinfo_base;
+	struct page *vmcoreinfo_pages[DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE)];
+	unsigned int order, nr_pages;
+	int i;
 	void *safecopy;
 
+	nr_pages = DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE);
+	order = get_order(VMCOREINFO_BYTES);
+
 	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
 		return 0;
 	if (image->type != KEXEC_TYPE_CRASH)
@@ -61,12 +67,15 @@ int kimage_crash_copy_vmcoreinfo(struct
 	 * happens to generate vmcoreinfo note, hereby we rely on
 	 * vmap for this purpose.
 	 */
-	vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
-	if (!vmcoreinfo_page) {
+	vmcoreinfo_base = kimage_alloc_control_pages(image, order);
+	if (!vmcoreinfo_base) {
 		pr_warn("Could not allocate vmcoreinfo buffer\n");
 		return -ENOMEM;
 	}
-	safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
+	for (i = 0; i < nr_pages; i++)
+		vmcoreinfo_pages[i] = vmcoreinfo_base + i;
+
+	safecopy = vmap(vmcoreinfo_pages, nr_pages, VM_MAP, PAGE_KERNEL);
 	if (!safecopy) {
 		pr_warn("Could not vmap vmcoreinfo buffer\n");
 		return -ENOMEM;
_

Patches currently in -mm which might be from pnina.feder@mobileye.com are

kernel-vmcoreinfo-allocate-vmcoreinfo_data-based-on-vmcoreinfo_bytes.patch
kernel-crash-handle-multi-page-vmcoreinfo-in-crash-kernel-copy.patch