+ mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch added to mm-new branch

+ mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages()
has been added to the -mm mm-new branch.  Its filename is
     mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch

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

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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   a) Consider who else should be cc'ed
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: mm/memremap: reject unreasonable folio/compound page sizes in memremap_pages()
Date: Mon, 1 Sep 2025 17:03:28 +0200

Let's reject unreasonable folio sizes early, where we can still fail. 
We'll add sanity checks to prepare_compound_head/prepare_compound_page
next.

Is there a way to configure a system such that unreasonable folio sizes
would be possible?  It would already be rather questionable.

If so, we'd probably want to bail out earlier, where we can avoid a WARN
and just report a proper error message that indicates where something went
wrong such that we messed up.

Link: https://lkml.kernel.org/r/20250901150359.867252-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memremap.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/memremap.c~mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages
+++ a/mm/memremap.c
@@ -275,6 +275,9 @@ void *memremap_pages(struct dev_pagemap
 
 	if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
 		return ERR_PTR(-EINVAL);
+	if (WARN_ONCE(pgmap->vmemmap_shift > MAX_FOLIO_ORDER,
+		      "requested folio size unsupported\n"))
+		return ERR_PTR(-EINVAL);
 
 	switch (pgmap->type) {
 	case MEMORY_DEVICE_PRIVATE:
_

Patches currently in -mm which might be from david@redhat.com are

mm-migrate-remove-migratepage_unmap.patch
mm-migrate-remove-migratepage_unmap-fix.patch
treewide-remove-migratepage_success.patch
mm-huge_memory-move-more-common-code-into-insert_pmd.patch
mm-huge_memory-move-more-common-code-into-insert_pud.patch
mm-huge_memory-support-huge-zero-folio-in-vmf_insert_folio_pmd.patch
fs-dax-use-vmf_insert_folio_pmd-to-insert-the-huge-zero-folio.patch
mm-huge_memory-mark-pmd-mappings-of-the-huge-zero-folio-special.patch
powerpc-ptdump-rename-struct-pgtable_level-to-struct-ptdump_pglevel.patch
mm-rmap-convert-enum-rmap_level-to-enum-pgtable_level.patch
mm-memory-convert-print_bad_pte-to-print_bad_page_map.patch
mm-memory-convert-print_bad_pte-to-print_bad_page_map-fix.patch
mm-memory-factor-out-common-code-from-vm_normal_page_.patch
mm-introduce-and-use-vm_normal_page_pud.patch
mm-rename-vm_ops-find_special_page-to-vm_ops-find_normal_page.patch
prctl-extend-pr_set_thp_disable-to-optionally-exclude-vm_hugepage.patch
mm-huge_memory-convert-tva_flags-to-enum-tva_type.patch
mm-huge_memory-respect-madv_collapse-with-pr_thp_disable_except_advised.patch
mm-stop-making-sparsemem_vmemmap-user-selectable.patch
arm64-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
s390-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
x86-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
wireguard-selftests-remove-config_sparsemem_vmemmap=y-from-qemu-kernel-config.patch
mm-page_alloc-reject-unreasonable-folio-compound-page-sizes-in-alloc_contig_range_noprof.patch
mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch
mm-hugetlb-check-for-unreasonable-folio-sizes-when-registering-hstate.patch
mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_page.patch
mm-sanity-check-maximum-folio-size-in-folio_set_order.patch
mm-limit-folio-compound-page-sizes-in-problematic-kernel-configs.patch
mm-simplify-folio_page-and-folio_page_idx.patch
mm-hugetlb-cleanup-hugetlb_folio_init_tail_vmemmap.patch
mm-mm-percpu-km-drop-nth_page-usage-within-single-allocation.patch
fs-hugetlbfs-remove-nth_page-usage-within-folio-in-adjust_range_hwpoison.patch
fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch
mm-pagewalk-drop-nth_page-usage-within-folio-in-folio_walk_start.patch
mm-gup-drop-nth_page-usage-within-folio-when-recording-subpages.patch
mm-gup-remove-record_subpages.patch
io_uring-zcrx-remove-nth_page-usage-within-folio.patch
mips-mm-convert-__flush_dcache_pages-to-__flush_dcache_folio_pages.patch
mm-cma-refuse-handing-out-non-contiguous-page-ranges.patch
dma-remap-drop-nth_page-in-dma_common_contiguous_remap.patch
scatterlist-disallow-non-contigous-page-ranges-in-a-single-sg-entry.patch
ata-libata-sff-drop-nth_page-usage-within-sg-entry.patch
drm-i915-gem-drop-nth_page-usage-within-sg-entry.patch
mspro_block-drop-nth_page-usage-within-sg-entry.patch
memstick-drop-nth_page-usage-within-sg-entry.patch
mmc-drop-nth_page-usage-within-sg-entry.patch
scsi-scsi_lib-drop-nth_page-usage-within-sg-entry.patch
scsi-sg-drop-nth_page-usage-within-sg-entry.patch
vfio-pci-drop-nth_page-usage-within-sg-entry.patch
crypto-remove-nth_page-usage-within-sg-entry.patch
mm-gup-drop-nth_page-usage-in-unpin_user_page_range_dirty_lock.patch
kfence-drop-nth_page-usage.patch
block-update-comment-of-struct-bio_vec-regarding-nth_page.patch
mm-remove-nth_page.patch