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_set_poison to set it as poisoned and grab a refcount on it. Signed-off-by: Oscar Salvador <[email protected]> --- mm/memory-failure.c | 20 +++++++++++----- mm/page_alloc.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+), 6 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 37b230b8cfe7..1d986580522d 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -78,6 +78,15 @@ EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor); EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask); EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value); +extern bool take_page_off_buddy(struct page *page); + +static void page_handle_poison(struct page *page) +{ + SetPageHWPoison(page); + page_ref_inc(page); + num_poisoned_pages_inc(); +} + static int hwpoison_filter_dev(struct page *p) { struct address_space *mapping; @@ -1830,14 +1839,13 @@ 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 a/mm/page_alloc.c b/mm/page_alloc.c index cd1dd0712624..255df0c76a40 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8632,6 +8632,74 @@ 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, + struct free_area *area, int migratetype) +{ + unsigned long size = 1 << high; + struct page *current_buddy, *next_page; + + while (high > low) { + area--; + 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_area(current_buddy, area, 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); + struct free_area *area = &(zone->free_area[buddy_order]); + + 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_area(page_head, area); + break_down_buddy_pages(zone, page_head, page, 0, + buddy_order, area, migratetype); + ret = true; + 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. -- 2.12.3
