mm: ksm: support hwpoison for ksm page

hwpoison_user_mappings() is updated to support ksm pages, and add
collect_procs_ksm() to collect processes when the error hit an ksm page. 
The difference from collect_procs_anon() is that it also needs to traverse
the rmap-item list on the stable node of the ksm page.  At the same time,
add_to_kill_ksm() is added to handle ksm pages.  And
task_in_to_kill_list() is added to avoid duplicate addition of tsk to the
to_kill list.  This is because when scanning the list, if the pages that
make up the ksm page all come from the same process, they may be added
repeatedly.

Link: https://lkml.kernel.org/r/20230414021741.2597273-3-xialonglong1@huawei.com
Signed-off-by: Longlong Xia <xialonglong1@huawei.com>
Tested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 290a3eb6d8de..37c63310bc4e 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2738,6 +2738,51 @@ again:
 		goto again;
 }
 
+#ifdef CONFIG_MEMORY_FAILURE
+/*
+ * Collect processes when the error hit an ksm page.
+ */
+void collect_procs_ksm(struct page *page, struct list_head *to_kill,
+		       int force_early)
+{
+	struct ksm_stable_node *stable_node;
+	struct ksm_rmap_item *rmap_item;
+	struct folio *folio = page_folio(page);
+	struct vm_area_struct *vma;
+	struct task_struct *tsk;
+
+	stable_node = folio_stable_node(folio);
+	if (!stable_node)
+		return;
+	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
+		struct anon_vma *av = rmap_item->anon_vma;
+
+		anon_vma_lock_read(av);
+		read_lock(&tasklist_lock);
+		for_each_process(tsk) {
+			struct anon_vma_chain *vmac;
+			unsigned long addr;
+			struct task_struct *t =
+				task_early_kill(tsk, force_early);
+			if (!t)
+				continue;
+			anon_vma_interval_tree_foreach(vmac, &av->rb_root, 0,
+						       ULONG_MAX)
+			{
+				vma = vmac->vma;
+				if (vma->vm_mm == t->mm) {
+					addr = rmap_item->address & PAGE_MASK;
+					add_to_kill_ksm(t, page, vma, to_kill,
+							addr);
+				}
+			}
+		}
+		read_unlock(&tasklist_lock);
+		anon_vma_unlock_read(av);
+	}
+}
+#endif
+
 #ifdef CONFIG_MIGRATION
 void folio_migrate_ksm(struct folio *newfolio, struct folio *folio)
 {