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kho: fix order calculation for kho_unpreserve_pages()

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Commit 91e74fa8b1 ("kho: make sure preservations do not span multiple
NUMA nodes") made sure preservations from kho_preserve_pages() do not
span multiple NUMA nodes. If they do, the order is reduced and tried
again.

The same logic was not implemented for kho_unpreserve_pages(). This can
result in unpreserve calculating a different order than preserve, and
thus not actually unpreserving the pages.

Fix this by moving the order calculation logic to
__kho_preserve_pages_order() and use it from both preserve and
unpreserve paths.

Move __kho_unpreserve() down to avoid having a forward declaration. Its
users are further down in the file anyway. Also, it results in grouping
for all the page-level preservation and unpreservation functions. This
unfortunately makes the diff hard to read, but the main change in
__kho_unpreserve() is to call __kho_preserve_pages_order() instead of
open-coding the order calculation.

Fixes: 91e74fa8b1 ("kho: make sure preservations do not span multiple NUMA nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Link: https://patch.msgid.link/20260519133332.2498092-1-pratyush@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
This commit is contained in:
Pratyush Yadav (Google)
2026-05-19 15:33:30 +02:00
committed by Mike Rapoport (Microsoft)
parent d64b037276
commit 8fd2f26fa2
1 changed files with 32 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
kernel/liveupdate/kexec_handover.c
View File

@@ -357,20 +357,6 @@ int kho_radix_walk_tree(struct kho_radix_tree *tree,
}
EXPORT_SYMBOL_GPL(kho_radix_walk_tree);
static void __kho_unpreserve(struct kho_radix_tree *tree,
unsigned long pfn, unsigned long end_pfn)
{
unsigned int order;
while (pfn < end_pfn) {
order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
kho_radix_del_page(tree, pfn, order);
pfn += 1 << order;
}
}
/* For physically contiguous 0-order pages. */
static void kho_init_pages(struct page *page, unsigned long nr_pages)
{
@@ -860,6 +846,37 @@ void kho_unpreserve_folio(struct folio *folio)
}
EXPORT_SYMBOL_GPL(kho_unpreserve_folio);
static unsigned int __kho_preserve_pages_order(unsigned long start_pfn,
unsigned long end_pfn)
{
unsigned int order = min(count_trailing_zeros(start_pfn),
ilog2(end_pfn - start_pfn));
/*
* Make sure all the pages in a single preservation are in the same NUMA
* node. The restore machinery can not cope with a preservation spanning
* multiple NUMA nodes.
*/
while (pfn_to_nid(start_pfn) != pfn_to_nid(start_pfn + (1UL << order) - 1))
order--;
return order;
}
static void __kho_unpreserve(struct kho_radix_tree *tree,
unsigned long pfn, unsigned long end_pfn)
{
unsigned int order;
while (pfn < end_pfn) {
order = __kho_preserve_pages_order(pfn, end_pfn);
kho_radix_del_page(tree, pfn, order);
pfn += 1 << order;
}
}
/**
* kho_preserve_pages - preserve contiguous pages across kexec
* @page: first page in the list.
@@ -885,16 +902,7 @@ int kho_preserve_pages(struct page *page, unsigned long nr_pages)
}
while (pfn < end_pfn) {
unsigned int order =
min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn));
/*
* Make sure all the pages in a single preservation are in the
* same NUMA node. The restore machinery can not cope with a
* preservation spanning multiple NUMA nodes.
*/
while (pfn_to_nid(pfn) != pfn_to_nid(pfn + (1UL << order) - 1))
order--;
unsigned int order = __kho_preserve_pages_order(pfn, end_pfn);
err = kho_radix_add_page(tree, pfn, order);
if (err) {