mm/vmalloc: defer freeing partly initialized vm_struct

mm/vmalloc: defer freeing partly initialized vm_struct

__vmalloc_area_node() may call free_vmap_area() or vfree() on error paths,
both of which can sleep.  This becomes problematic if the function is
invoked from an atomic context, such as when GFP_ATOMIC or GFP_NOWAIT is
passed via gfp_mask.

To fix this, unify error paths and defer the cleanup of partly initialized
vm_struct objects to a workqueue.  This ensures that freeing happens in a
process context and avoids invalid sleeps in atomic regions.

Link: https://lkml.kernel.org/r/20251007122035.56347-5-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>