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

On Wed, 24 Jun 2020 at 20:32, [off-list ref] wrote:

quoted

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 <redacted>
---
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.