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>

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 7e232ba59b86567c57cee6dbb5d9d6dbf63c31aa..d9e701326a88258574bd43be33d710533957a60d 100644 (file)
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -51,6 +51,10 @@ struct page *ksm_might_need_to_copy(struct page *page,
 void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc);
 void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);
 
+#ifdef CONFIG_MEMORY_FAILURE
+void collect_procs_ksm(struct page *page, struct list_head *to_kill,
+                      int force_early);
+#endif
 #else  /* !CONFIG_KSM */
 
 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
@@ -62,6 +66,13 @@ static inline void ksm_exit(struct mm_struct *mm)
 {
 }
 
+#ifdef CONFIG_MEMORY_FAILURE
+static inline void collect_procs_ksm(struct page *page,
+                                    struct list_head *to_kill, int force_early)
+{
+}
+#endif
+
 #ifdef CONFIG_MMU
 static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
                unsigned long end, int advice, unsigned long *vm_flags)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2772a1800cf3df19111e42e276761fc379eff6b8..37554b08bb28f7ea32e4dd8ed0b4a5b4f20857b3 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3604,6 +3604,7 @@ extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
                                        bool *migratable_cleared);
 void num_poisoned_pages_inc(unsigned long pfn);
 void num_poisoned_pages_sub(unsigned long pfn, long i);
+struct task_struct *task_early_kill(struct task_struct *tsk, int force_early);
 #else
 static inline void memory_failure_queue(unsigned long pfn, int flags)
 {
@@ -3624,6 +3625,12 @@ static inline void num_poisoned_pages_sub(unsigned long pfn, long i)
 }
 #endif
 
+#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_KSM)
+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);
+#endif
+
 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_MEMORY_HOTPLUG)
 extern void memblk_nr_poison_inc(unsigned long pfn);
 extern void memblk_nr_poison_sub(unsigned long pfn, long i);

diff --git a/mm/ksm.c b/mm/ksm.c
index 290a3eb6d8de727a14ad423702af07d0b9ed03fb..37c63310bc4e431e9000c0e71ad64be4996a7a5f 100644 (file)
--- 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)
 {

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index bb09999108ef8d76ef64f579011be611fd5cc273..f69c410fb9f96585b4169ad6df1196d1f0e3b38a 100644 (file)
--- 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;