The patch titled
Subject: mm,hwpoison: rework soft offline for free pages
has been added to the -mm tree. Its filename is
mmhwpoison-rework-soft-offline-for-free-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmhwpoison-rework-soft-offline-for-free-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmhwpoison-rework-soft-offline-for-free-pages.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxx>
Subject: mm,hwpoison: rework soft offline for free pages
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.
Link: http://lkml.kernel.org/r/20200806184923.7007-8-nao.horiguchi@xxxxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxxx>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dmitry Yakunin <zeil@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-flags.h | 1
mm/memory-failure.c | 18 ++++++---
mm/page_alloc.c | 68 +++++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+), 6 deletions(-)
--- a/include/linux/page-flags.h~mmhwpoison-rework-soft-offline-for-free-pages
+++ a/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)
--- a/mm/memory-failure.c~mmhwpoison-rework-soft-offline-for-free-pages
+++ a/mm/memory-failure.c
@@ -65,6 +65,13 @@ int sysctl_memory_failure_recovery __rea
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;
@@ -1882,14 +1889,13 @@ static int soft_offline_in_use_page(stru
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;
}
--- a/mm/page_alloc.c~mmhwpoison-rework-soft-offline-for-free-pages
+++ a/mm/page_alloc.c
@@ -8773,6 +8773,74 @@ bool is_free_buddy_page(struct page *pag
#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
* allocation.
_
Patches currently in -mm which might be from osalvador@xxxxxxx are
mmhwpoison-un-export-get_hwpoison_page-and-make-it-static.patch
mmhwpoison-kill-put_hwpoison_page.patch
mmhwpoison-unify-thp-handling-for-hard-and-soft-offline.patch
mmhwpoison-rework-soft-offline-for-free-pages.patch
mmhwpoison-rework-soft-offline-for-in-use-pages.patch
mmhwpoison-refactor-soft_offline_huge_page-and-__soft_offline_page.patch
mmhwpoison-return-0-if-the-page-is-already-poisoned-in-soft-offline.patch
