kexec: export free_huge_page to VMCOREINFO

PG_head_mask was added into VMCOREINFO to filter huge pages in b3acc56bfe1
("kexec: save PG_head_mask in VMCOREINFO"), but makedumpfile still need
another symbol to filter *hugetlbfs* pages.

If a user hope to filter user pages, makedumpfile tries to exclude them by
checking the condition whether the page is anonymous, but hugetlbfs pages
aren't anonymous while they also be user pages.

We know it's possible to detect them in the same way as PageHuge(),
so we need the start address of free_huge_page():

    int PageHuge(struct page *page)
    {
            if (!PageCompound(page))
                    return 0;

            page = compound_head(page);
            return get_compound_page_dtor(page) == free_huge_page;
    }

For that reason, this patch changes free_huge_page() into public
to export it to VMCOREINFO.

Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 255cd5cc07541034fd0f80e1d944ca775b6c78df..a23c096b30807c20db8d967dbb130f4842fa44e2 100644 (file)
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -80,6 +80,7 @@ int dequeue_hwpoisoned_huge_page(struct page *page);
 bool isolate_huge_page(struct page *page, struct list_head *list);
 void putback_active_hugepage(struct page *page);
 bool is_hugepage_active(struct page *page);
+void free_huge_page(struct page *page);
 
 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud);

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 369f41a9412481029354034d4c6e0193fe132f56..23a088fec3c0a62e10f6ad149cb684f1b5de8364 100644 (file)
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -33,6 +33,7 @@
 #include <linux/swap.h>
 #include <linux/syscore_ops.h>
 #include <linux/compiler.h>
+#include <linux/hugetlb.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -1619,6 +1620,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 #endif
        VMCOREINFO_NUMBER(PG_head_mask);
        VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
+       VMCOREINFO_SYMBOL(free_huge_page);
 
        arch_crash_save_vmcoreinfo();
        update_vmcoreinfo_note();

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 9221c02ed9e2b8ab495e0b39482e2bcfa5ba9957..7a0a73d2fcff128850b32af9910a873d6fb384f5 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -856,7 +856,7 @@ struct hstate *size_to_hstate(unsigned long size)
        return NULL;
 }
 
-static void free_huge_page(struct page *page)
+void free_huge_page(struct page *page)
 {
        /*
         * Can't pass hstate in here because it is called from the