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, 5 insertions, 5 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 962e2a1..2dcd335 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -894,9 +894,9 @@ void page_move_anon_rmap(struct page *page,
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 
-	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON(!anon_vma);
-	VM_BUG_ON(page->index != linear_page_index(vma, address));
+	VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
 
 	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
 	page->mapping = (struct address_space *) anon_vma;
@@ -995,7 +995,7 @@ void do_page_add_anon_rmap(struct page *page,
 	if (unlikely(PageKsm(page)))
 		return;
 
-	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	/* address might be in next vma when migration races vma_adjust */
 	if (first)
 		__page_set_anon_rmap(page, vma, address, exclusive);
@@ -1481,7 +1481,7 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
 		.anon_lock = page_lock_anon_vma_read,
 	};
 
-	VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
+	VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
 
 	/*
 	 * During exec, a temporary VMA is setup and later moved.
@@ -1533,7 +1533,7 @@ int try_to_munlock(struct page *page)
 
 	};
 
-	VM_BUG_ON(!PageLocked(page) || PageLRU(page));
+	VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
 
 	ret = rmap_walk(page, &rwc);
 	return ret;