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, 25 insertions, 9 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index bb09999108ef..f69c410fb9f9 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -455,6 +455,27 @@ static void add_to_kill_anon_file(struct task_struct *tsk, struct page *p,
 	__add_to_kill(tsk, p, vma, to_kill, 0, FSDAX_INVALID_PGOFF);
 }
 
+#ifdef CONFIG_KSM
+static bool task_in_to_kill_list(struct list_head *to_kill,
+				 struct task_struct *tsk)
+{
+	struct to_kill *tk, *next;
+
+	list_for_each_entry_safe(tk, next, to_kill, nd) {
+		if (tk->tsk == tsk)
+			return true;
+	}
+
+	return false;
+}
+void add_to_kill_ksm(struct task_struct *tsk, struct page *p,
+		     struct vm_area_struct *vma, struct list_head *to_kill,
+		     unsigned long ksm_addr)
+{
+	if (!task_in_to_kill_list(to_kill, tsk))
+		__add_to_kill(tsk, p, vma, to_kill, ksm_addr, FSDAX_INVALID_PGOFF);
+}
+#endif
 /*
  * Kill the processes that have been collected earlier.
  *
@@ -534,8 +555,7 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
  * processes sharing the same error page,if the process is "early kill", the
  * task_struct of the dedicated thread will also be returned.
  */
-static struct task_struct *task_early_kill(struct task_struct *tsk,
-					   int force_early)
+struct task_struct *task_early_kill(struct task_struct *tsk, int force_early)
 {
 	if (!tsk->mm)
 		return NULL;
@@ -666,8 +686,9 @@ static void collect_procs(struct page *page, struct list_head *tokill,
 {
 	if (!page->mapping)
 		return;
-
-	if (PageAnon(page))
+	if (unlikely(PageKsm(page)))
+		collect_procs_ksm(page, tokill, force_early);
+	else if (PageAnon(page))
 		collect_procs_anon(page, tokill, force_early);
 	else
 		collect_procs_file(page, tokill, force_early);
@@ -1522,11 +1543,6 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	if (!page_mapped(hpage))
 		return true;
 
-	if (PageKsm(p)) {
-		pr_err("%#lx: can't handle KSM pages.\n", pfn);
-		return false;
-	}
-
 	if (PageSwapCache(p)) {
 		pr_err("%#lx: keeping poisoned page in swap cache\n", pfn);
 		ttu &= ~TTU_HWPOISON;