Commit 06be6ff3 authored by Oscar Salvador's avatar Oscar Salvador Committed by Linus Torvalds
Browse files

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.

Signed-off-by: default avatarOscar Salvador <osalvador@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Aristeu Rozanski <aris@ruivo.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Yakunin <zeil@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200922135650.1634-9-osalvador@suse.de


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 694bf0b0

include/linux/page-flags.h

+1 −0
Original line number Diff line number Diff line
@@ -432,6 +432,7 @@ 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)

mm/memory-failure.c

+12 −6
Original line number Diff line number Diff line
@@ -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;
@@ -1884,14 +1891,13 @@ static int soft_offline_in_use_page(struct page *page, int flags) 


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;

}

mm/page_alloc.c

+68 −0
Original line number Diff line number Diff line
@@ -8777,6 +8777,74 @@ 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

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