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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-01-16 03:54:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-16 04:56:32 +0300
commite9b61f19858a5d6c42ce2298cf138279375d0d9b (patch)
treeba2f5851d193c0ab96af67a9df9856b1dd9480ad /include/linux/huge_mm.h
parent4e41a30c6d506c884d3da9aeb316352e70679d4b (diff)
downloadlinux-e9b61f19858a5d6c42ce2298cf138279375d0d9b.tar.xz
thp: reintroduce split_huge_page()
This patch adds implementation of split_huge_page() for new refcountings. Unlike previous implementation, new split_huge_page() can fail if somebody holds GUP pin on the page. It also means that pin on page would prevent it from bening split under you. It makes situation in many places much cleaner. The basic scheme of split_huge_page(): - Check that sum of mapcounts of all subpage is equal to page_count() plus one (caller pin). Foll off with -EBUSY. This way we can avoid useless PMD-splits. - Freeze the page counters by splitting all PMD and setup migration PTEs. - Re-check sum of mapcounts against page_count(). Page's counts are stable now. -EBUSY if page is pinned. - Split compound page. - Unfreeze the page by removing migration entries. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/huge_mm.h')
-rw-r--r--include/linux/huge_mm.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f1fa1c283be1..90e11e6a37ab 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -90,8 +90,11 @@ extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
extern unsigned long transparent_hugepage_flags;
-#define split_huge_page_to_list(page, list) BUILD_BUG()
-#define split_huge_page(page) BUILD_BUG()
+int split_huge_page_to_list(struct page *page, struct list_head *list);
+static inline int split_huge_page(struct page *page)
+{
+ return split_huge_page_to_list(page, NULL);
+}
void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long address);