[PATCH v2] HWPOISON: Fix the handling path of the victimized page frame that belong to non-LUR

[Chen Yucong <slaoub@gmail.com>]

Until now, the kernel has the same policy to handle victimized page frames that
belong to kernel-space(reserved/slab-subsystem) or non-LRU(unknown page state).
In other word, the result of handling either of these victimized page frames is
(IGNORED | FAILED), and the return value of memory_failure() is -EBUSY.

This patch is to avoid that memory_failure() returns very soon due to the "true"
value of (!PageLRU(p)), and it also ensures that action_result() can report more
precise information("reserved kernel",  "kernel slab", and "unknown page state")
instead of "non LRU", especially for memory errors which are detected by memory-scrubbing.

Changes since v1: http://www.spinics.net/lists/linux-mm/msg74044.html
  - Call goto just after if (hwpoison_filter(p)) block, and jump directly to just 
    before the code determining the page_state, as suggested by Naoya Horiguchi.

Signed-off-by: Chen Yucong <slaoub@gmail.com>
---
 mm/memory-failure.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index e3154d9..1340b30 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -862,7 +862,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	struct page *hpage = *hpagep;
 	struct page *ppage;
 
-	if (PageReserved(p) || PageSlab(p))
+	if (PageReserved(p) || PageSlab(p) || !PageLRU(p))
 		return SWAP_SUCCESS;
 
 	/*
@@ -1126,9 +1126,6 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 					action_result(pfn, "free buddy, 2nd try", DELAYED);
 				return 0;
 			}
-			action_result(pfn, "non LRU", IGNORED);
-			put_page(p);
-			return -EBUSY;
 		}
 	}
 
@@ -1161,6 +1158,9 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 		return 0;
 	}
 
+	if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p))
+		goto identify_page_state;
+
 	/*
 	 * For error on the tail page, we should set PG_hwpoison
 	 * on the head page to show that the hugepage is hwpoisoned
@@ -1210,6 +1210,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 		goto out;
 	}
 
+identify_page_state:
 	res = -EBUSY;
 	/*
 	 * The first check uses the current page flags which may not have any
-- 
1.7.10.4

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