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From: nao.horiguchi@gmail.com
To: linux-mm@kvack.org
Cc: mhocko@kernel.org, akpm@linux-foundation.org,
	mike.kravetz@oracle.com, osalvador@suse.de, tony.luck@intel.com,
	david@redhat.com, aneesh.kumar@linux.vnet.ibm.com,
	zeil@yandex-team.ru, cai@lca.pw, naoya.horiguchi@nec.com,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 11/16] mm,hwpoison: Rework soft offline for free pages
Date: Fri, 31 Jul 2020 12:21:07 +0000
Message-ID: <20200731122112.11263-12-nao.horiguchi@gmail.com> (raw)
In-Reply-To: <20200731122112.11263-1-nao.horiguchi@gmail.com>

From: Oscar Salvador <osalvador@suse.de>

When trying to soft-offline a free page, we need to first take it off
the buddy allocator.
Once we know is out of reach, we can safely flag it as poisoned.

take_page_off_buddy will be used to take a page meant to be poisoned
off the buddy allocator.
take_page_off_buddy calls break_down_buddy_pages, which splits a
higher-order page in case our page belongs to one.

Once the page is under our control, we call page_handle_poison to set it
as poisoned and grab a refcount on it.

Signed-off-by: Oscar Salvador <osalvador@suse.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
ChangeLog v4 -> v5:
- fix comile error

ChangeLog v2 -> v3:
- use add_to_free_list() instead of add_to_free_area()
- use del_page_from_free_list() instead of del_page_from_free_area()
- add fast return
- move extern definition to header file as warned by checkpatch.pl
---
 include/linux/page-flags.h |  1 +
 mm/memory-failure.c        | 18 ++++++----
 mm/page_alloc.c            | 68 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+), 6 deletions(-)

diff --git v5.8-rc7-mmotm-2020-07-27-18-18/include/linux/page-flags.h v5.8-rc7-mmotm-2020-07-27-18-18_patched/include/linux/page-flags.h
index 6be1aa559b1e..9fa5d4e2d69a 100644
--- v5.8-rc7-mmotm-2020-07-27-18-18/include/linux/page-flags.h
+++ v5.8-rc7-mmotm-2020-07-27-18-18_patched/include/linux/page-flags.h
@@ -423,6 +423,7 @@ PAGEFLAG(HWPoison, hwpoison, PF_ANY)
 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
 #define __PG_HWPOISON (1UL << PG_hwpoison)
 extern bool set_hwpoison_free_buddy_page(struct page *page);
+extern bool take_page_off_buddy(struct page *page);
 #else
 PAGEFLAG_FALSE(HWPoison)
 static inline bool set_hwpoison_free_buddy_page(struct page *page)
diff --git v5.8-rc7-mmotm-2020-07-27-18-18/mm/memory-failure.c v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/memory-failure.c
index 803f4b2ac510..8b6a98929b54 100644
--- v5.8-rc7-mmotm-2020-07-27-18-18/mm/memory-failure.c
+++ v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/memory-failure.c
@@ -65,6 +65,13 @@ int sysctl_memory_failure_recovery __read_mostly = 1;
 
 atomic_long_t num_poisoned_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
+static void page_handle_poison(struct page *page)
+{
+	SetPageHWPoison(page);
+	page_ref_inc(page);
+	num_poisoned_pages_inc();
+}
+
 #if defined(CONFIG_HWPOISON_INJECT) || defined(CONFIG_HWPOISON_INJECT_MODULE)
 
 u32 hwpoison_filter_enable = 0;
@@ -1873,14 +1880,13 @@ static int soft_offline_in_use_page(struct page *page)
 
 static int soft_offline_free_page(struct page *page)
 {
-	int rc = dissolve_free_huge_page(page);
+	int rc = -EBUSY;
 
-	if (!rc) {
-		if (set_hwpoison_free_buddy_page(page))
-			num_poisoned_pages_inc();
-		else
-			rc = -EBUSY;
+	if (!dissolve_free_huge_page(page) && take_page_off_buddy(page)) {
+		page_handle_poison(page);
+		rc = 0;
 	}
+
 	return rc;
 }
 
diff --git v5.8-rc7-mmotm-2020-07-27-18-18/mm/page_alloc.c v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/page_alloc.c
index efe2e94c45f5..aab89f7db4ac 100644
--- v5.8-rc7-mmotm-2020-07-27-18-18/mm/page_alloc.c
+++ v5.8-rc7-mmotm-2020-07-27-18-18_patched/mm/page_alloc.c
@@ -8776,6 +8776,74 @@ bool is_free_buddy_page(struct page *page)
 }
 
 #ifdef CONFIG_MEMORY_FAILURE
+/*
+ * Break down a higher-order page in sub-pages, and keep our target out of
+ * buddy allocator.
+ */
+static void break_down_buddy_pages(struct zone *zone, struct page *page,
+				   struct page *target, int low, int high,
+				   int migratetype)
+{
+	unsigned long size = 1 << high;
+	struct page *current_buddy, *next_page;
+
+	while (high > low) {
+		high--;
+		size >>= 1;
+
+		if (target >= &page[size]) {
+			next_page = page + size;
+			current_buddy = page;
+		} else {
+			next_page = page;
+			current_buddy = page + size;
+		}
+
+		if (set_page_guard(zone, current_buddy, high, migratetype))
+			continue;
+
+		if (current_buddy != target) {
+			add_to_free_list(current_buddy, zone, high, migratetype);
+			set_page_order(current_buddy, high);
+			page = next_page;
+		}
+	}
+}
+
+/*
+ * Take a page that will be marked as poisoned off the buddy allocator.
+ */
+bool take_page_off_buddy(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long flags;
+	unsigned int order;
+	bool ret = false;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	for (order = 0; order < MAX_ORDER; order++) {
+		struct page *page_head = page - (pfn & ((1 << order) - 1));
+		int buddy_order = page_order(page_head);
+
+		if (PageBuddy(page_head) && buddy_order >= order) {
+			unsigned long pfn_head = page_to_pfn(page_head);
+			int migratetype = get_pfnblock_migratetype(page_head,
+								   pfn_head);
+
+			del_page_from_free_list(page_head, zone, buddy_order);
+			break_down_buddy_pages(zone, page_head, page, 0,
+						buddy_order, migratetype);
+			ret = true;
+			break;
+		}
+		if (page_count(page_head) > 0)
+			break;
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+	return ret;
+}
+
 /*
  * Set PG_hwpoison flag if a given page is confirmed to be a free page.  This
  * test is performed under the zone lock to prevent a race against page
-- 
2.17.1



  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31 12:20 [PATCH v5 00/16] HWPOISON: soft offline rework nao.horiguchi
2020-07-31 12:20 ` [PATCH v5 01/16] mm,hwpoison: cleanup unused PageHuge() check nao.horiguchi
2020-07-31 12:20 ` [PATCH v5 02/16] mm, hwpoison: remove recalculating hpage nao.horiguchi
2020-07-31 12:20 ` [PATCH v5 03/16] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 04/16] mm,madvise: Refactor madvise_inject_error nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 05/16] mm,hwpoison-inject: don't pin for hwpoison_filter nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 06/16] mm,hwpoison: Un-export get_hwpoison_page and make it static nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 07/16] mm,hwpoison: Kill put_hwpoison_page nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 08/16] mm,hwpoison: remove MF_COUNT_INCREASED nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 09/16] mm,hwpoison: remove flag argument from soft offline functions nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 10/16] mm,hwpoison: Unify THP handling for hard and soft offline nao.horiguchi
2020-07-31 12:21 ` nao.horiguchi [this message]
2020-07-31 12:21 ` [PATCH v5 12/16] mm,hwpoison: Rework soft offline for in-use pages nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 13/16] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 14/16] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline nao.horiguchi
2020-07-31 12:21 ` [PATCH v5 15/16] mm,hwpoison: introduce MF_MSG_UNSPLIT_THP nao.horiguchi
     [not found] ` <20200803123954.GA4631@lca.pw>
2020-08-03 13:36   ` [PATCH v5 00/16] HWPOISON: soft offline rework HORIGUCHI NAOYA(堀口 直也)
     [not found]     ` <20200803151907.GA8894@lca.pw>
2020-08-05 20:43       ` HORIGUCHI NAOYA(堀口 直也)
     [not found] ` <20200803190709.GB8894@lca.pw>
2020-08-04  1:16   ` HORIGUCHI NAOYA(堀口 直也)
2020-08-04  1:49     ` Qian Cai
2020-08-04  8:13       ` osalvador
2020-08-05 20:44       ` HORIGUCHI NAOYA(堀口 直也)

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