diff options
| author | Lorenzo Stoakes <lorenzo.stoakes@oracle.com> | 2026-01-18 14:50:39 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-01-26 20:02:21 -0800 |
| commit | 69e945845585e415fe18afcddbca7cdd215ff3c7 (patch) | |
| tree | b0a5a97c6dd8c8dbe5e01d50ed20272233bf1959 | |
| parent | 91901a441fa19d56bdc2c45b76f4165585af773b (diff) | |
mm/rmap: skip unfaulted VMAs on anon_vma clone, unlink
For both anon_vma_clone() and unlink_anon_vmas(), if the source VMA or the
VMA to be linked are unfaulted (e.g. !vma->anon_vma), then the functions
do nothing. Simply exit early in these cases.
In the unlink_anon_vmas() case we can also remove a conditional that
checks whether vma->anon_vma is set.
Link: https://lkml.kernel.org/r/085a25f7528e1c8c687276e9b856e88dc8f105ca.1768746221.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chriscli@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/rmap.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index fe2fd9ab0dea..3c5fb8fb105f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -313,6 +313,9 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) check_anon_vma_clone(dst, src); + if (!src->anon_vma) + return 0; + list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { struct anon_vma *anon_vma; @@ -478,7 +481,10 @@ void unlink_anon_vmas(struct vm_area_struct *vma) mmap_assert_locked(vma->vm_mm); /* Unfaulted is a no-op. */ - VM_WARN_ON_ONCE(!vma->anon_vma && !list_empty(&vma->anon_vma_chain)); + if (!vma->anon_vma) { + VM_WARN_ON_ONCE(!list_empty(&vma->anon_vma_chain)); + return; + } /* * Unlink each anon_vma chained to the VMA. This list is ordered @@ -502,15 +508,13 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_del(&avc->same_vma); anon_vma_chain_free(avc); } - if (vma->anon_vma) { - vma->anon_vma->num_active_vmas--; - /* - * vma would still be needed after unlink, and anon_vma will be prepared - * when handle fault. - */ - vma->anon_vma = NULL; - } + vma->anon_vma->num_active_vmas--; + /* + * vma would still be needed after unlink, and anon_vma will be prepared + * when handle fault. + */ + vma->anon_vma = NULL; unlock_anon_vma_root(root); /* |