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, 18 insertions, 18 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 95d1acb0f3d2..25fab7150fa0 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -712,7 +712,7 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
         pgtable_t pgtable;
         spinlock_t *ptl;
 
-        VM_BUG_ON(!PageCompound(page));
+        VM_BUG_ON_PAGE(!PageCompound(page), page);
         pgtable = pte_alloc_one(mm, haddr);
         if (unlikely(!pgtable))
                 return VM_FAULT_OOM;
@@ -893,7 +893,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                 goto out;
         }
         src_page = pmd_page(pmd);
-        VM_BUG_ON(!PageHead(src_page));
+        VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
         get_page(src_page);
         page_dup_rmap(src_page);
         add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
@@ -1067,7 +1067,7 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
         ptl = pmd_lock(mm, pmd);
         if (unlikely(!pmd_same(*pmd, orig_pmd)))
                 goto out_free_pages;
-        VM_BUG_ON(!PageHead(page));
+        VM_BUG_ON_PAGE(!PageHead(page), page);
 
         pmdp_clear_flush(vma, haddr, pmd);
         /* leave pmd empty until pte is filled */
@@ -1133,7 +1133,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 goto out_unlock;
 
         page = pmd_page(orig_pmd);
-        VM_BUG_ON(!PageCompound(page) || !PageHead(page));
+        VM_BUG_ON_PAGE(!PageCompound(page) || !PageHead(page), page);
         if (page_mapcount(page) == 1) {
                 pmd_t entry;
                 entry = pmd_mkyoung(orig_pmd);
@@ -1211,7 +1211,7 @@ alloc:
                         add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
                         put_huge_zero_page();
                 } else {
-                        VM_BUG_ON(!PageHead(page));
+                        VM_BUG_ON_PAGE(!PageHead(page), page);
                         page_remove_rmap(page);
                         put_page(page);
                 }
@@ -1249,7 +1249,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
                 goto out;
 
         page = pmd_page(*pmd);
-        VM_BUG_ON(!PageHead(page));
+        VM_BUG_ON_PAGE(!PageHead(page), page);
         if (flags & FOLL_TOUCH) {
                 pmd_t _pmd;
                 /*
@@ -1274,7 +1274,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
                 }
         }
         page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
-        VM_BUG_ON(!PageCompound(page));
+        VM_BUG_ON_PAGE(!PageCompound(page), page);
         if (flags & FOLL_GET)
                 get_page_foll(page);
 
@@ -1432,9 +1432,9 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                 } else {
                         page = pmd_page(orig_pmd);
                         page_remove_rmap(page);
-                        VM_BUG_ON(page_mapcount(page) < 0);
+                        VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
                         add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
-                        VM_BUG_ON(!PageHead(page));
+                        VM_BUG_ON_PAGE(!PageHead(page), page);
                         atomic_long_dec(&tlb->mm->nr_ptes);
                         spin_unlock(ptl);
                         tlb_remove_page(tlb, page);
@@ -2176,9 +2176,9 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
                 if (unlikely(!page))
                         goto out;
 
-                VM_BUG_ON(PageCompound(page));
-                BUG_ON(!PageAnon(page));
-                VM_BUG_ON(!PageSwapBacked(page));
+                VM_BUG_ON_PAGE(PageCompound(page), page);
+                VM_BUG_ON_PAGE(!PageAnon(page), page);
+                VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 
                 /* cannot use mapcount: can't collapse if there's a gup pin */
                 if (page_count(page) != 1)
@@ -2201,8 +2201,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
                 }
                 /* 0 stands for page_is_file_cache(page) == false */
                 inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
-                VM_BUG_ON(!PageLocked(page));
-                VM_BUG_ON(PageLRU(page));
+                VM_BUG_ON_PAGE(!PageLocked(page), page);
+                VM_BUG_ON_PAGE(PageLRU(page), page);
 
                 /* If there is no mapped pte young don't collapse the page */
                 if (pte_young(pteval) || PageReferenced(page) ||
@@ -2232,7 +2232,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
                 } else {
                         src_page = pte_page(pteval);
                         copy_user_highpage(page, src_page, address, vma);
-                        VM_BUG_ON(page_mapcount(src_page) != 1);
+                        VM_BUG_ON_PAGE(page_mapcount(src_page) != 1, src_page);
                         release_pte_page(src_page);
                         /*
                          * ptl mostly unnecessary, but preempt has to
@@ -2311,7 +2311,7 @@ static struct page
                        struct vm_area_struct *vma, unsigned long address,
                        int node)
 {
-        VM_BUG_ON(*hpage);
+        VM_BUG_ON_PAGE(*hpage, *hpage);
         /*
          * Allocate the page while the vma is still valid and under
          * the mmap_sem read mode so there is no memory allocation
@@ -2580,7 +2580,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
                  */
                 node = page_to_nid(page);
                 khugepaged_node_load[node]++;
-                VM_BUG_ON(PageCompound(page));
+                VM_BUG_ON_PAGE(PageCompound(page), page);
                 if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
                         goto out_unmap;
                 /* cannot use mapcount: can't collapse if there's a gup pin */
@@ -2876,7 +2876,7 @@ again:
                 return;
         }
         page = pmd_page(*pmd);
-        VM_BUG_ON(!page_count(page));
+        VM_BUG_ON_PAGE(!page_count(page), page);
         get_page(page);
         spin_unlock(ptl);
         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);