+ mm-mmap-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled.patch added to mm-hotfixes-unstable branch

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

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

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-thp-is-enabled-v5-1-c6c38cfefd6e@kuka.com
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);
 }
 
_

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