linux-kernel - [PATCH v1 2/9] mm: hugetlb: return immediately for hugetlb page in __delete_from_page

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Message-Id: <1496305019-5493-3-git-send-email-n-horiguchi@ah.jp.nec.com>
Date:   Thu,  1 Jun 2017 17:16:52 +0900
From:   Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: [PATCH v1 2/9] mm: hugetlb: return immediately for hugetlb page in __delete_from_page_cache()

We avoid calling __mod_node_page_state(NR_FILE_PAGES) for hugetlb page
now, but it's not enough because later code doesn't handle hugetlb
properly.  Actually in our testing, WARN_ON_ONCE(PageDirty(page)) at the
end of this function fires for hugetlb, which makes no sense.  So we
should return immediately for hugetlb pages.

Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
 mm/filemap.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git v4.12-rc3/mm/filemap.c v4.12-rc3_patched/mm/filemap.c
index 6f1be57..2867fcb 100644
--- v4.12-rc3/mm/filemap.c
+++ v4.12-rc3_patched/mm/filemap.c
@@ -239,14 +239,16 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 	/* Leave page->index set: truncation lookup relies upon it */
 
 	/* hugetlb pages do not participate in page cache accounting. */
-	if (!PageHuge(page))
-		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
+	if (PageHuge(page))
+		return;
+
+	__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, -nr);
 	if (PageSwapBacked(page)) {
 		__mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr);
 		if (PageTransHuge(page))
 			__dec_node_page_state(page, NR_SHMEM_THPS);
 	} else {
-		VM_BUG_ON_PAGE(PageTransHuge(page) && !PageHuge(page), page);
+		VM_BUG_ON_PAGE(PageTransHuge(page), page);
 	}
 
 	/*
-- 
2.7.0