hwpoison: use page_cgroup_ino for filtering by memcg

Hwpoison allows to filter pages by memory cgroup ino.  Currently, it
calls try_get_mem_cgroup_from_page to obtain the cgroup from a page and
then its ino using cgroup_ino, but now we have a helper method for
that, page_cgroup_ino, so use it instead.

This patch also loosens the hwpoison memcg filter dependency rules - it
makes it depend on CONFIG_MEMCG instead of CONFIG_MEMCG_SWAP, because
hwpoison memcg filter does not require anything (nor it used to) from
CONFIG_MEMCG_SWAP side.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 3 insertions, 18 deletions

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index aeba0edd6e44..9d26fd9fefe4 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -45,12 +45,9 @@ static int hwpoison_inject(void *data, u64 val)
         /*
          * do a racy check with elevated page count, to make sure PG_hwpoison
          * will only be set for the targeted owner (or on a free page).
-         * We temporarily take page lock for try_get_mem_cgroup_from_page().
          * memory_failure() will redo the check reliably inside page lock.
          */
-        lock_page(hpage);
         err = hwpoison_filter(hpage);
-        unlock_page(hpage);
         if (err)
                 goto put_out;
 
@@ -126,7 +123,7 @@ static int pfn_inject_init(void)
         if (!dentry)
                 goto fail;
 
-#ifdef CONFIG_MEMCG_SWAP
+#ifdef CONFIG_MEMCG
         dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
                                     hwpoison_dir, &hwpoison_filter_memcg);
         if (!dentry)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index eeda6485e76c..95882692e747 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -130,27 +130,15 @@ static int hwpoison_filter_flags(struct page *p)
  * can only guarantee that the page either belongs to the memcg tasks, or is
  * a freed page.
  */
-#ifdef  CONFIG_MEMCG_SWAP
+#ifdef CONFIG_MEMCG
 u64 hwpoison_filter_memcg;
 EXPORT_SYMBOL_GPL(hwpoison_filter_memcg);
 static int hwpoison_filter_task(struct page *p)
 {
-        struct mem_cgroup *mem;
-        struct cgroup_subsys_state *css;
-        unsigned long ino;
-
         if (!hwpoison_filter_memcg)
                 return 0;
 
-        mem = try_get_mem_cgroup_from_page(p);
-        if (!mem)
-                return -EINVAL;
-
-        css = &mem->css;
-        ino = cgroup_ino(css->cgroup);
-        css_put(css);
-
-        if (ino != hwpoison_filter_memcg)
+        if (page_cgroup_ino(p) != hwpoison_filter_memcg)
                 return -EINVAL;
 
         return 0;