Re: [PATCH v3 13/15] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page

Naresh Kamboju
2020-06-26T16:53:59Z

On Wed, 24 Jun 2020 at 20:32, <nao.horiguchi@gmail.com> wrote:
>
> From: Oscar Salvador <osalvador@suse.de>
>
> Merging soft_offline_huge_page and __soft_offline_page let us get rid of
> quite some duplicated code, and makes the code much easier to follow.
>
> Now, __soft_offline_page will handle both normal and hugetlb pages.
>
> Note that move put_page() block to the beginning of page_handle_poison()
> with drain_all_pages() in order to make sure that the target page is
> freed and sent into free list to make take_page_off_buddy() work properly.
>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
> ChangeLog v2 -> v3:
> - use page_is_file_lru() instead of page_is_file_cache(),
> - add description about put_page() and drain_all_pages().
> - fix coding style warnings by checkpatch.pl
> ---
> mm/memory-failure.c | 185 ++++++++++++++++++++------------------------
> 1 file changed, 86 insertions(+), 99 deletions(-)
>
> diff --git v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
> index f744eb90c15c..22c904f6d17a 100644
> --- v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c
> +++ v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
> @@ -78,14 +78,36 @@ EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
> EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
> EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);
>
> -static void page_handle_poison(struct page *page, bool release)
> +static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
> {
> + if (release) {
> + put_page(page);
> + drain_all_pages(page_zone(page));
> + }
> +
> + if (hugepage_or_freepage) {
> + /*
> + * Doing this check for free pages is also fine since dissolve_free_huge_page
> + * returns 0 for non-hugetlb pages as well.
> + */
> + if (dissolve_free_huge_page(page) || !take_page_off_buddy(page))
> + /*
> + * The hugetlb page can end up being enqueued back into
> + * the freelists by means of:
> + * unmap_and_move_huge_page
> + * putback_active_hugepage
> + * put_page->free_huge_page
> + * enqueue_huge_page
> + * If this happens, we might lose the race against an allocation.
> + */
> + return false;
> + }
>
> SetPageHWPoison(page);
> - if (release)
> - put_page(page);
> page_ref_inc(page);
> num_poisoned_pages_inc();
> +
> + return true;
> }
>
> static int hwpoison_filter_dev(struct page *p)
> @@ -1718,63 +1740,52 @@ static int get_any_page(struct page *page, unsigned long pfn)
> return ret;
> }
>
> -static int soft_offline_huge_page(struct page *page)
> +static bool isolate_page(struct page *page, struct list_head *pagelist)
> {
> - int ret;
> - unsigned long pfn = page_to_pfn(page);
> - struct page *hpage = compound_head(page);
> - LIST_HEAD(pagelist);
> + bool isolated = false;
> + bool lru = PageLRU(page);
> +
> + if (PageHuge(page)) {
> + isolated = isolate_huge_page(page, pagelist);
> + } else {
> + if (lru)
> + isolated = !isolate_lru_page(page);
> + else
> + isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
> +
> + if (isolated)
> + list_add(&page->lru, pagelist);
>
> - /*
> - * This double-check of PageHWPoison is to avoid the race with
> - * memory_failure(). See also comment in __soft_offline_page().
> - */
> - lock_page(hpage);
> - if (PageHWPoison(hpage)) {
> - unlock_page(hpage);
> - put_page(hpage);
> - pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
> - return -EBUSY;
> }
> - unlock_page(hpage);
>
> - ret = isolate_huge_page(hpage, &pagelist);
> + if (isolated && lru)
> + inc_node_page_state(page, NR_ISOLATED_ANON +
> + page_is_file_lru(page));
> +
> /*
> - * get_any_page() and isolate_huge_page() takes a refcount each,
> - * so need to drop one here.
> + * If we succeed to isolate the page, we grabbed another refcount on
> + * the page, so we can safely drop the one we got from get_any_pages().
> + * If we failed to isolate the page, it means that we cannot go further
> + * and we will return an error, so drop the reference we got from
> + * get_any_pages() as well.
> */
> - put_page(hpage);
> - if (!ret) {
> - pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
> - return -EBUSY;
> - }
> -
> - ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
> - MIGRATE_SYNC, MR_MEMORY_FAILURE);
> - if (ret) {
> - pr_info("soft offline: %#lx: hugepage migration failed %d, type %lx (%pGp)\n",
> - pfn, ret, page->flags, &page->flags);
> - if (!list_empty(&pagelist))
> - putback_movable_pages(&pagelist);
> - if (ret > 0)
> - ret = -EIO;
> - } else {
> - /*
> - * We set PG_hwpoison only when we were able to take the page
> - * off the buddy.
> - */
> - if (!dissolve_free_huge_page(page) && take_page_off_buddy(page))
> - page_handle_poison(page, false);
> - else
> - ret = -EBUSY;
> - }
> - return ret;
> + put_page(page);
> + return isolated;
> }
>
> +/*
> + * __soft_offline_page handles hugetlb-pages and non-hugetlb pages.
> + * If the page is a non-dirty unmapped page-cache page, it simply invalidates.
> + * If the page is mapped, it migrates the contents over.
> + */
> static int __soft_offline_page(struct page *page)
> {
> - int ret;
> + int ret = 0;
> unsigned long pfn = page_to_pfn(page);
> + struct page *hpage = compound_head(page);
> + const char *msg_page[] = {"page", "hugepage"};
> + bool huge = PageHuge(page);
> + LIST_HEAD(pagelist);
>
> /*
> * Check PageHWPoison again inside page lock because PageHWPoison
> @@ -1783,98 +1794,74 @@ static int __soft_offline_page(struct page *page)
> * so there's no race between soft_offline_page() and memory_failure().
> */
> lock_page(page);
> - wait_on_page_writeback(page);
> + if (!PageHuge(page))
> + wait_on_page_writeback(page);
> if (PageHWPoison(page)) {
> unlock_page(page);
> put_page(page);
> pr_info("soft offline: %#lx page already poisoned\n", pfn);
> return -EBUSY;
> }
> - /*
> - * Try to invalidate first. This should work for
> - * non dirty unmapped page cache pages.
> - */
> - ret = invalidate_inode_page(page);
> +
> + if (!PageHuge(page))
> + /*
> + * Try to invalidate first. This should work for
> + * non dirty unmapped page cache pages.
> + */
> + ret = invalidate_inode_page(page);
> unlock_page(page);
> +
> /*
> * RED-PEN would be better to keep it isolated here, but we
> * would need to fix isolation locking first.
> */
> - if (ret == 1) {
> + if (ret) {
> pr_info("soft_offline: %#lx: invalidated\n", pfn);
> - page_handle_poison(page, true);
> + page_handle_poison(page, false, true);

arm64 build failed on linux-next 20200626 tag

make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=arm64
CROSS_COMPILE=aarch64-linux-gnu- HOSTCC=gcc CC="sccache
aarch64-linux-gnu-gcc" O=build Image
79 #
80 ../mm/memory-failure.c: In function ‘__soft_offline_page’:
81 ../mm/memory-failure.c:1827:3: error: implicit declaration of
function ‘page_handle_poison’; did you mean ‘page_init_poison’?
[-Werror=implicit-function-declaration]
82 1827 | page_handle_poison(page, false, true);
83 | ^~~~~~~~~~~~~~~~~~
84 | page_init_poison

--
Linaro LKFT