[PATCH V3 1/2] MCE: fix an error of mce_bad_pages statistics

From: Xishi Qiu
Date: Tue Dec 11 2012 - 07:18:59 EST


1) move poisoned page check at the beginning of the function.
2) add page_lock to avoid unpoison clear the flag.

Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx>
ïSigned-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
---
mm/memory-failure.c | 43 ++++++++++++++++++++++---------------------
1 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8b20278..9b74983 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1419,18 +1419,17 @@ static int soft_offline_huge_page(struct page *page, int flags)
unsigned long pfn = page_to_pfn(page);
struct page *hpage = compound_head(page);

+ if (PageHWPoison(hpage)) {
+ pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
+ return -EBUSY;
+ }
+
ret = get_any_page(page, pfn, flags);
if (ret < 0)
return ret;
if (ret == 0)
goto done;

- if (PageHWPoison(hpage)) {
- put_page(hpage);
- pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
- return -EBUSY;
- }
-
/* Keep page count to indicate a given hugepage is isolated. */
ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, false,
MIGRATE_SYNC);
@@ -1441,12 +1440,14 @@ static int soft_offline_huge_page(struct page *page, int flags)
return ret;
}
done:
- if (!PageHWPoison(hpage))
- atomic_long_add(1 << compound_trans_order(hpage),
- &mce_bad_pages);
+ /* keep elevated page count for bad page */
+ lock_page(hpage);
+ atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
set_page_hwpoison_huge_page(hpage);
+ unlock_page(hpage);
+
dequeue_hwpoisoned_huge_page(hpage);
- /* keep elevated page count for bad page */
+
return ret;
}

@@ -1488,6 +1489,11 @@ int soft_offline_page(struct page *page, int flags)
}
}

+ if (PageHWPoison(page)) {
+ pr_info("soft offline: %#lx page already poisoned\n", pfn);
+ return -EBUSY;
+ }
+
ret = get_any_page(page, pfn, flags);
if (ret < 0)
return ret;
@@ -1519,19 +1525,11 @@ int soft_offline_page(struct page *page, int flags)
return -EIO;
}

- lock_page(page);
- wait_on_page_writeback(page);
-
/*
* Synchronized using the page lock with memory_failure()
*/
- if (PageHWPoison(page)) {
- unlock_page(page);
- put_page(page);
- pr_info("soft offline: %#lx page already poisoned\n", pfn);
- return -EBUSY;
- }
-
+ lock_page(page);
+ wait_on_page_writeback(page);
/*
* Try to invalidate first. This should work for
* non dirty unmapped page cache pages.
@@ -1582,8 +1580,11 @@ int soft_offline_page(struct page *page, int flags)
return ret;

done:
+ /* keep elevated page count for bad page */
+ lock_page(page);
atomic_long_add(1, &mce_bad_pages);
SetPageHWPoison(page);
- /* keep elevated page count for bad page */
+ unlock_page(page);
+
return ret;
}
--
1.7.1


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