mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE

Most of the VM_BUG_ON assertions are performed on a page.  Usually, when
one of these assertions fails we'll get a BUG_ON with a call stack and
the registers.

I've recently noticed based on the requests to add a small piece of code
that dumps the page to various VM_BUG_ON sites that the page dump is
quite useful to people debugging issues in mm.

This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
VM_BUG_ON() does, also dumps the page before executing the actual
BUG_ON.

[akpm@linux-foundation.org: fix up includes]
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 0596e8e0cc19..207d9aef662d 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -108,8 +108,8 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
 
 static inline void get_head_page_multiple(struct page *page, int nr)
 {
-        VM_BUG_ON(page != compound_head(page));
-        VM_BUG_ON(page_count(page) == 0);
+        VM_BUG_ON_PAGE(page != compound_head(page), page);
+        VM_BUG_ON_PAGE(page_count(page) == 0, page);
         atomic_add(nr, &page->_count);
         SetPageReferenced(page);
 }
@@ -135,7 +135,7 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
         head = pte_page(pte);
         page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
         do {
-                VM_BUG_ON(compound_head(page) != head);
+                VM_BUG_ON_PAGE(compound_head(page) != head, page);
                 pages[*nr] = page;
                 if (PageTail(page))
                         get_huge_page_tail(page);
@@ -212,7 +212,7 @@ static noinline int gup_huge_pud(pud_t pud, unsigned long addr,
         head = pte_page(pte);
         page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
         do {
-                VM_BUG_ON(compound_head(page) != head);
+                VM_BUG_ON_PAGE(compound_head(page) != head, page);
                 pages[*nr] = page;
                 if (PageTail(page))
                         get_huge_page_tail(page);