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Groups > linux.kernel > #1507867

[PATCHv4 10/43] thp: try to free page's buffers before attempt split

From "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Newsgroups linux.kernel
Subject [PATCHv4 10/43] thp: try to free page's buffers before attempt split
Date 2016-10-25 02:20 +0200
Message-ID <svXDd-6uQ-51@gated-at.bofh.it> (permalink)
References <svXDb-6uQ-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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We want page to be isolated from the rest of the system before spliting
it. We rely on page count to be 2 for file pages to make sure nobody
uses the page: one pin to caller, one to radix-tree.

Filesystems with backing storage can have page count increased if it has
buffers.

Let's try to free them, before attempt split. And remove one guarding
VM_BUG_ON_PAGE().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/buffer_head.h |  1 +
 mm/huge_memory.c            | 19 ++++++++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index ebbacd14d450..006a8a42acfb 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -395,6 +395,7 @@ extern int __set_page_dirty_buffers(struct page *page);
 #else /* CONFIG_BLOCK */
 
 static inline void buffer_init(void) {}
+static inline int page_has_buffers(struct page *page) { return 0; }
 static inline int try_to_free_buffers(struct page *page) { return 1; }
 static inline int inode_has_buffers(struct inode *inode) { return 0; }
 static inline void invalidate_inode_buffers(struct inode *inode) {}
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e7cda8e86f2c..40fe91ac383c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -30,6 +30,7 @@
 #include <linux/userfaultfd_k.h>
 #include <linux/page_idle.h>
 #include <linux/shmem_fs.h>
+#include <linux/buffer_head.h>
 
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
@@ -2066,7 +2067,6 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 
 	VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
 
 	if (PageAnon(head)) {
@@ -2095,6 +2095,23 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 			goto out;
 		}
 
+		/* Try to free buffers before attempt split */
+		if (!PageSwapBacked(head) && PagePrivate(page)) {
+			/*
+			 * We cannot trigger writeback from here due possible
+			 * recursion if triggered from vmscan, only wait.
+			 *
+			 * Caller can trigger writeback it on its own, if safe.
+			 */
+			wait_on_page_writeback(head);
+
+			if (page_has_buffers(head) && !try_to_release_page(head,
+						GFP_KERNEL)) {
+				ret = -EBUSY;
+				goto out;
+			}
+		}
+
 		/* Addidional pin from radix tree */
 		extra_pins = 1;
 		anon_vma = NULL;
-- 
2.9.3

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[PATCHv4 00/43] ext4: support of huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 02/43] radix tree test suite: Allow GFP_ATOMIC allocations to fail "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 34/43] ext4: handle huge pages in __ext4_block_zero_page_range() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 26/43] fs: make block_page_mkwrite() aware about huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 40/43] ext4: fix SEEK_DATA/SEEK_HOLE for huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 42/43] mm, fs, ext4: expand use of page_mapping() and page_to_pgoff() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 41/43] ext4: make fallocate() operations work with huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 09/43] mm, rmap: account file thp pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 35/43] ext4: make ext4_block_write_begin() aware about huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 06/43] mm, shmem: swich huge tmpfs to multi-order radix-tree entries "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 36/43] ext4: handle huge pages in ext4_da_write_end() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 10/43] thp: try to free page's buffers before attempt split "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 11/43] thp: handle write-protection faults for file THP "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:20 +0200
  [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if huge page cache enabled "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
    Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled Christoph Hellwig <hch@infradead.org> - 2016-10-25 09:30 +0200
      Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-10-26 00:40 +0200
        Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if huge page cache enabled Andreas Dilger <adilger@dilger.ca> - 2016-10-26 06:20 +0200
          Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled Ming Lei <tom.leiming@gmail.com> - 2016-10-26 09:40 +0200
            Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled Christoph Hellwig <hch@infradead.org> - 2016-10-26 09:40 +0200
          Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled Christoph Hellwig <hch@infradead.org> - 2016-10-26 09:40 +0200
        Re: [PATCHv4 18/43] block: define BIO_MAX_PAGES to HPAGE_PMD_NR if  huge page cache enabled Christoph Hellwig <hch@infradead.org> - 2016-10-26 09:40 +0200
  [PATCHv4 30/43] mm: account huge pages to dirty, writaback, reclaimable, etc. "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 31/43] ext4: make ext4_mpage_readpages() hugepage-aware "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 17/43] HACK: readahead: alloc huge pages, if allowed "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 20/43] mm: make write_cache_pages() work on huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 21/43] thp: introduce hpage_size() and hpage_mask() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 01/43] tools: Add WARN_ON_ONCE "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 08/43] page-flags: relax page flag policy for few flags "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 39/43] ext4: make EXT4_IOC_MOVE_EXT work with huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 32/43] ext4: make ext4_writepage() work on huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 13/43] filemap: allocate huge page in page_cache_read(), if allowed "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 28/43] truncate: make invalidate_inode_pages2_range() aware about huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 03/43] radix-tree: Add radix_tree_join "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 15/43] filemap: allocate huge page in pagecache_get_page(), if allowed "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 29/43] mm, hugetlb: switch hugetlbfs to multi-order radix-tree entries "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 23/43] thp: make thp_get_unmapped_area() respect S_HUGE_MODE "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200
  [PATCHv4 24/43] fs: make block_read_full_page() be able to read huge page "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-10-25 02:30 +0200

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