[PATCH] [9/21] HWPOISON: Handle hardware poisoned pages in try_to_unmap

From: Andi Kleen
Date: Fri Sep 11 2009 - 14:51:23 EST



From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

When a page has the poison bit set replace the PTE with a poison entry.
This causes the right error handling to be done later when a process runs
into it.

v2: add a new flag to not do that (needed for the memory-failure handler
later) (Fengguang)
v3: remove unnecessary is_migration_entry() test (Fengguang, Minchan)

Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Reviewed-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
include/linux/rmap.h | 1 +
mm/rmap.c | 9 ++++++++-
2 files changed, 9 insertions(+), 1 deletion(-)

Index: linux/mm/rmap.c
===================================================================
--- linux.orig/mm/rmap.c
+++ linux/mm/rmap.c
@@ -820,7 +820,14 @@ static int try_to_unmap_one(struct page
/* Update high watermark before we lower rss */
update_hiwater_rss(mm);

- if (PageAnon(page)) {
+ if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+ if (PageAnon(page))
+ dec_mm_counter(mm, anon_rss);
+ else
+ dec_mm_counter(mm, file_rss);
+ set_pte_at(mm, address, pte,
+ swp_entry_to_pte(make_hwpoison_entry(page)));
+ } else if (PageAnon(page)) {
swp_entry_t entry = { .val = page_private(page) };

if (PageSwapCache(page)) {
Index: linux/include/linux/rmap.h
===================================================================
--- linux.orig/include/linux/rmap.h
+++ linux/include/linux/rmap.h
@@ -93,6 +93,7 @@ enum ttu_flags {

TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
+ TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
};
#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)

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