[RFC][PATCH v1 05/11] mm: hwpoison-inject: don't pin for hwpoison_filter()

[Naoya Horiguchi]

Another memory error injection interface debugfs:hwpoison/corrupt-pfn
also takes bogus refcount for hwpoison_filter(). It's justified
because this does a coarse filter, expecting that memory_failure()
redoes the check for sure.

Signed-off-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
---
 mm/hwpoison-inject.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git v4.19-mmotm-2018-10-30-16-08/mm/hwpoison-inject.c 
v4.19-mmotm-2018-10-30-16-08_patched/mm/hwpoison-inject.c
index b6ac706..766062c 100644
--- v4.19-mmotm-2018-10-30-16-08/mm/hwpoison-inject.c
+++ v4.19-mmotm-2018-10-30-16-08_patched/mm/hwpoison-inject.c
@@ -25,11 +25,6 @@ static int hwpoison_inject(void *data, u64 val)
 
        p = pfn_to_page(pfn);
        hpage = compound_head(p);
-       /*
-        * This implies unable to support free buddy pages.
-        */
-       if (!get_hwpoison_page(p))
-               return 0;
 
        if (!hwpoison_filter_enable)
                goto inject;
@@ -39,23 +34,20 @@ static int hwpoison_inject(void *data, u64 val)
         * This implies unable to support non-LRU pages.
         */
        if (!PageLRU(hpage) && !PageHuge(p))
-               goto put_out;
+               return 0;
 
        /*
-        * 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).
+        * do a racy check to make sure PG_hwpoison will only be set for
+        * the targeted owner (or on a free page).
         * memory_failure() will redo the check reliably inside page lock.
         */
        err = hwpoison_filter(hpage);
        if (err)
-               goto put_out;
+               return 0;
 
 inject:
        pr_info("Injecting memory failure at pfn %#lx\n", pfn);
-       return memory_failure(pfn, MF_COUNT_INCREASED);
-put_out:
-       put_hwpoison_page(p);
-       return 0;
+       return memory_failure(pfn, 0);
 }
 
 static int hwpoison_unpoison(void *data, u64 val)
-- 
2.7.0