linux-kernel - [PATCH] [9/15] HWPOISON: Handle hardware poisoned pages in try_to

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Message-Id: <20090804215308.553F4B15D8@basil.firstfloor.org>
Date:	Tue,  4 Aug 2009 23:53:08 +0200 (CEST)
From:	Andi Kleen <andi@...stfloor.org>
To:	akpm@...ux-foundation.org, linux-mm@...r.kernel.org,
	linux-kernel@...r.kernel.org, fengguang.wu@...el.com
Subject: [PATCH] [9/15] HWPOISON: Handle hardware poisoned pages in try_to_unmap


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.

Also add a new flag to not do that (needed for the memory-failure handler
later)

Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 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
@@ -819,7 +819,14 @@ 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 if (!is_migration_entry(pte_to_swp_entry(*pte)))
+			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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