Ignacio Moreno Gonzalez 7190b3c8bd mm: mmap: map MAP_STACK to VM_NOHUGEPAGE only if THP is enabled ...

commit c4608d1bf7 ("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: c4608d1bf7 ("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>

2025-05-20 22:49:38 -07:00

5.4 KiB

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