linux-kernel - [PATCH v2 1/2] kho: use unsigned long for nr

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Message-ID: <20260116112217.915803-2-pratyush@kernel.org>
Date: Fri, 16 Jan 2026 11:22:14 +0000
From: Pratyush Yadav <pratyush@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Graf <graf@...zon.com>,
	Mike Rapoport <rppt@...nel.org>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Pratyush Yadav <pratyush@...nel.org>
Cc: kexec@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Suren Baghdasaryan <surenb@...gle.com>
Subject: [PATCH v2 1/2] kho: use unsigned long for nr_pages

With 4k pages, a 32-bit nr_pages can span up to 16 TiB. While it is a
lot, there exist systems with terabytes of RAM. gup is also moving to
using long for nr_pages. Use unsigned long and make KHO future-proof.

Suggested-by: Pasha Tatashin <pasha.tatashin@...een.com>
Signed-off-by: Pratyush Yadav <pratyush@...nel.org>
---

Changes in v2:
- New in v2.

 include/linux/kexec_handover.h     |  6 +++---
 kernel/liveupdate/kexec_handover.c | 11 ++++++-----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/linux/kexec_handover.h b/include/linux/kexec_handover.h
index 5f7b9de97e8d..81814aa92370 100644
--- a/include/linux/kexec_handover.h
+++ b/include/linux/kexec_handover.h
@@ -45,15 +45,15 @@ bool is_kho_boot(void);
 
 int kho_preserve_folio(struct folio *folio);
 void kho_unpreserve_folio(struct folio *folio);
-int kho_preserve_pages(struct page *page, unsigned int nr_pages);
-void kho_unpreserve_pages(struct page *page, unsigned int nr_pages);
+int kho_preserve_pages(struct page *page, unsigned long nr_pages);
+void kho_unpreserve_pages(struct page *page, unsigned long nr_pages);
 int kho_preserve_vmalloc(void *ptr, struct kho_vmalloc *preservation);
 void kho_unpreserve_vmalloc(struct kho_vmalloc *preservation);
 void *kho_alloc_preserve(size_t size);
 void kho_unpreserve_free(void *mem);
 void kho_restore_free(void *mem);
 struct folio *kho_restore_folio(phys_addr_t phys);
-struct page *kho_restore_pages(phys_addr_t phys, unsigned int nr_pages);
+struct page *kho_restore_pages(phys_addr_t phys, unsigned long nr_pages);
 void *kho_restore_vmalloc(const struct kho_vmalloc *preservation);
 int kho_add_subtree(const char *name, void *fdt);
 void kho_remove_subtree(void *fdt);
diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 9dc51fab604f..709484fbf9fd 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -222,7 +222,8 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn,
 static struct page *kho_restore_page(phys_addr_t phys, bool is_folio)
 {
 	struct page *page = pfn_to_online_page(PHYS_PFN(phys));
-	unsigned int nr_pages, ref_cnt;
+	unsigned long nr_pages;
+	unsigned int ref_cnt;
 	union kho_page_info info;
 
 	if (!page)
@@ -249,7 +250,7 @@ static struct page *kho_restore_page(phys_addr_t phys, bool is_folio)
 	 * count of 1
 	 */
 	ref_cnt = is_folio ? 0 : 1;
-	for (unsigned int i = 1; i < nr_pages; i++)
+	for (unsigned long i = 1; i < nr_pages; i++)
 		set_page_count(page + i, ref_cnt);
 
 	if (is_folio && info.order)
@@ -283,7 +284,7 @@ EXPORT_SYMBOL_GPL(kho_restore_folio);
  *
  * Return: 0 on success, error code on failure
  */
-struct page *kho_restore_pages(phys_addr_t phys, unsigned int nr_pages)
+struct page *kho_restore_pages(phys_addr_t phys, unsigned long nr_pages)
 {
 	const unsigned long start_pfn = PHYS_PFN(phys);
 	const unsigned long end_pfn = start_pfn + nr_pages;
@@ -829,7 +830,7 @@ EXPORT_SYMBOL_GPL(kho_unpreserve_folio);
  *
  * Return: 0 on success, error code on failure
  */
-int kho_preserve_pages(struct page *page, unsigned int nr_pages)
+int kho_preserve_pages(struct page *page, unsigned long nr_pages)
 {
 	struct kho_mem_track *track = &kho_out.track;
 	const unsigned long start_pfn = page_to_pfn(page);
@@ -873,7 +874,7 @@ EXPORT_SYMBOL_GPL(kho_preserve_pages);
  * kho_preserve_pages() call. Unpreserving arbitrary sub-ranges of larger
  * preserved blocks is not supported.
  */
-void kho_unpreserve_pages(struct page *page, unsigned int nr_pages)
+void kho_unpreserve_pages(struct page *page, unsigned long nr_pages)
 {
 	struct kho_mem_track *track = &kho_out.track;
 	const unsigned long start_pfn = page_to_pfn(page);
-- 
2.52.0.457.g6b5491de43-goog