FROMGIT: mm: mark vmas detached upon exit

When exit_mmap() removes vmas belonging to an exiting task, it does not
mark them as detached since they can't be reached by other tasks and they
will be freed shortly.  Once we introduce vma reuse, all vmas will have to
be in detached state before they are freed to ensure vma when reused is in
a consistent state.  Add missing vma_mark_detached() before freeing the
vma.

Link: https://lkml.kernel.org/r/20250213224655.1680278-6-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
  Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 07e140d532ac4ba6a438357df06bd746b555037f
https: //git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable)
Bug: 322132947
Change-Id: I590d1f18f71400a946580eaac4c6d60ec113e5ef
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

mm/vma.c

@@ -330,10 +330,12 @@ void remove_vma(struct vm_area_struct *vma, bool unreachable)
 	if (vma->vm_file)
 		fput(vma->vm_file);
 	mpol_put(vma_policy(vma));
-	if (unreachable)
+	if (unreachable) {
+		vma_mark_detached(vma);
 		__vm_area_free(vma);
-	else
+	} else {
 		vm_area_free(vma);
+	}
 }
 
 /*