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>
diff --git a/mm/ksm.c b/mm/ksm.c
index 3df141e..f91ddf5 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1898,13 +1898,13 @@
int ret = SWAP_AGAIN;
int search_new_forks = 0;
- VM_BUG_ON(!PageKsm(page));
+ VM_BUG_ON_PAGE(!PageKsm(page), page);
/*
* Rely on the page lock to protect against concurrent modifications
* to that page's node of the stable tree.
*/
- VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
stable_node = page_stable_node(page);
if (!stable_node)
@@ -1958,13 +1958,13 @@
{
struct stable_node *stable_node;
- VM_BUG_ON(!PageLocked(oldpage));
- VM_BUG_ON(!PageLocked(newpage));
- VM_BUG_ON(newpage->mapping != oldpage->mapping);
+ VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
+ VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+ VM_BUG_ON_PAGE(newpage->mapping != oldpage->mapping, newpage);
stable_node = page_stable_node(newpage);
if (stable_node) {
- VM_BUG_ON(stable_node->kpfn != page_to_pfn(oldpage));
+ VM_BUG_ON_PAGE(stable_node->kpfn != page_to_pfn(oldpage), oldpage);
stable_node->kpfn = page_to_pfn(newpage);
/*
* newpage->mapping was set in advance; now we need smp_wmb()