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

Naoya Horiguchi
2020-06-28T06:54:20Z

On Fri, Jun 26, 2020 at 10:23:43PM +0530, Naresh Kamboju wrote:
> 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

Thanks for reporting, Naresh, Qian Cai.

page_handle_poison() is now defined in #ifdef CONFIG_HWPOISON_INJECT block,
which is not correct because this function is used in non-injection code
path. I'd like to move this function out of the block and it affects
multiple patches in this series, so maybe I have to update/resend the whole
series, but I like to wait for a few days for other reviews, so for quick
fix for linux-next I suggest the following one.

Andrew, could you append this diff on top of this series on mmotm?

Thanks,
Naoya Horiguchi
---
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index e90ddddab397..b49590bc5615 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -78,38 +78,6 @@ EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);

-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);
- page_ref_inc(page);
- num_poisoned_pages_inc();
-
- return true;
-}
-
static int hwpoison_filter_dev(struct page *p)
{
struct address_space *mapping;
@@ -204,6 +172,38 @@ int hwpoison_filter(struct page *p)

EXPORT_SYMBOL_GPL(hwpoison_filter);

+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);
+ page_ref_inc(page);
+ num_poisoned_pages_inc();
+
+ return true;
+}
+
/*
* Kill all processes that have a poisoned page mapped and then isolate
* the page.