Re: [PATCH] mm/rmap: fix missing barrier between anon_vma init and vma->anon_vma publish
flat view
From: Rik van Riel <riel@surriel.com>
Date: 2026-09-05 13:24:07
On Sat, 2026-09-05 at 14:18 +0800, Jinjiang Tu wrote:
quoted hunk ↗ jump to hunk
diff --git a/mm/rmap.c b/mm/rmap.c index d1819fd69938..a868e835eadb 100644 --- a/mm/rmap.c +++ b/mm/rmap.c@@ -209,7 +209,11 @@ int __anon_vma_prepare(struct vm_area_struct*vma) /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); if (likely(!vma->anon_vma)) { - vma->anon_vma = anon_vma; + /* + * The fields of anon_vma must be visible before anon_vma + * is published to vma->anon_vma. + */ + smp_store_release(&vma->anon_vma, anon_vma); anon_vma_chain_assign(vma, avc, anon_vma); anon_rmap_tree_insert(avc, anon_vma); anon_vma->num_active_vmas++;
Nice catch on this bug! This is perhaps a dumb question, but does this write side barrier need to pair with a read side barrier, to ensure the reads are also correctly ordered? -- All Rights Reversed.