[BUG] random kernel crashes after THP rework on s390 (maybe also on PowerPC and ARM)
From: Kirill A. Shutemov <hidden>
Date: 2016-02-24 09:14:03
Also in:
linux-mm, linuxppc-dev, lkml
Subsystem:
memory management, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Linus Torvalds
On Tue, Feb 23, 2016 at 07:19:07PM +0100, Gerald Schaefer wrote:
I'll check with Martin, maybe it is actually trivial, then we can do a quick test it to rule that one out.
Oh. I found a bug in __split_huge_pmd_locked(). Although, not sure if it's _the_ bug. pmdp_invalidate() is called for the wrong address :-/ I guess that can be destructive on the architecture, right? Could you check this?
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1c317b85ea7d..4246bc70e55a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -2865,7 +2865,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pgtable = pgtable_trans_huge_withdraw(mm, pmd); pmd_populate(mm, &_pmd, pgtable); - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { + for (i = 0; i < HPAGE_PMD_NR; i++) { pte_t entry, *pte; /* * Note that NUMA hinting access restrictions are not
@@ -2886,9 +2886,9 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, } if (dirty) SetPageDirty(page + i); - pte = pte_offset_map(&_pmd, haddr); + pte = pte_offset_map(&_pmd, haddr + i * PAGE_SIZE); BUG_ON(!pte_none(*pte)); - set_pte_at(mm, haddr, pte, entry); + set_pte_at(mm, haddr + i * PAGE_SIZE, pte, entry); atomic_inc(&page[i]._mapcount); pte_unmap(pte); }
@@ -2938,7 +2938,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pmd_populate(mm, pmd, pgtable); if (freeze) { - for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) { + for (i = 0; i < HPAGE_PMD_NR; i++) { page_remove_rmap(page + i, false); put_page(page + i); }
--
Kirill A. Shutemov