The patch titled Subject: mm: mmap: map MAP_STACK to VM_NOHUGEPAGE only if THP is enabled has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-mmap-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

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

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------------------------------------------------------ From: Ignacio Moreno Gonzalez Ignacio.MorenoGonzalez@kuka.com Subject: mm: mmap: map MAP_STACK to VM_NOHUGEPAGE only if THP is enabled Date: Wed, 07 May 2025 15:28:06 +0200

commit c4608d1bf7c6 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE") maps the mmap option MAP_STACK to VM_NOHUGEPAGE. This is also done if CONFIG_TRANSPARENT_HUGEPAGE is not defined. But in that case, the VM_NOHUGEPAGE does not make sense.

I discovered this issue when trying to use the tool CRIU to checkpoint and restore a container. Our running kernel is compiled without CONFIG_TRANSPARENT_HUGEPAGE. CRIU parses the output of /proc/<pid>/smaps and saves the "nh" flag. When trying to restore the container, CRIU fails to restore the "nh" mappings, since madvise() MADV_NOHUGEPAGE always returns an error because CONFIG_TRANSPARENT_HUGEPAGE is not defined.

Link: https://lkml.kernel.org/r/20250507-map-map_stack-to-vm_nohugepage-only-if-th... Fixes: c4608d1bf7c6 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE") Signed-off-by: Ignacio Moreno Gonzalez Ignacio.MorenoGonzalez@kuka.com Acked-by: David Hildenbrand david@redhat.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Yang Shi yang@os.amperecomputing.com Reviewed-by: Liam R. Howlett Liam.Howlett@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

include/linux/mman.h | 2 ++ 1 file changed, 2 insertions(+)

--- a/include/linux/mman.h~mm-mmap-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled +++ a/include/linux/mman.h @@ -155,7 +155,9 @@ calc_vm_flag_bits(struct file *file, uns return _calc_vm_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN ) | _calc_vm_trans(flags, MAP_LOCKED, VM_LOCKED ) | _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) | +#ifdef CONFIG_TRANSPARENT_HUGEPAGE _calc_vm_trans(flags, MAP_STACK, VM_NOHUGEPAGE) | +#endif arch_calc_vm_flag_bits(file, flags); }

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Patches currently in -mm which might be from Ignacio.MorenoGonzalez@kuka.com are

mm-mmap-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled.patch