Generic pgtable_trans_huge_deposit()/pgtable_trans_huge_withdraw()
assume pgtable_t to be struct page * which is not true for all arches.
Thus arc, s390, sparch end up with their own copies despite no special
hardware requirements (unlike powerpc).
It seems massaging the code a bit can make it reusbale.
- Use explicit casts to (struct page *). For existing users, this
should be semantically no-op for existing users
- The only addition is zero'ing out of page->lru which for arc leaves
a stray entry in pgtable_t cause mm spew when such pgtable is freed.
| huge_memory: BUG: failure at
| ../mm/huge_memory.c:1858/__split_huge_page_map()!
| CPU: 0 PID: 901 Comm: bw_mem Not tainted 4.4.0-00015-g0569c1459cfa-dirty
|
| Stack Trace:
| arc_unwind_core.constprop.1+0x94/0x104
| split_huge_page_to_list+0x5c0/0x920
| __split_huge_page_pmd+0xc8/0x1b4
| vma_adjust_trans_huge+0x104/0x1c8
| vma_adjust+0xf8/0x6d8
| __split_vma.isra.40+0xf8/0x174
| do_munmap+0x360/0x428
| SyS_munmap+0x28/0x44
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-arch@xxxxxxxxxxxxxxx
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
mm/pgtable-generic.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index 75664ed7e3ab..c9f2f6f8c7bb 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -155,13 +155,17 @@ void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable)
{
+ struct page *new = (struct page *)pgtable;
+ struct page *head;
+
assert_spin_locked(pmd_lockptr(mm, pmdp));
/* FIFO */
- if (!pmd_huge_pte(mm, pmdp))
- INIT_LIST_HEAD(&pgtable->lru);
+ head = (struct page *)pmd_huge_pte(mm, pmdp);
+ if (!head)
+ INIT_LIST_HEAD(&new->lru);
else
- list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
+ list_add(&new->lru, &head->lru);
pmd_huge_pte(mm, pmdp) = pgtable;
}
#endif
@@ -170,20 +174,23 @@ void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
/* no "address" argument so destroys page coloring of some arch */
pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
- pgtable_t pgtable;
+ struct page *page;
assert_spin_locked(pmd_lockptr(mm, pmdp));
+ page = (struct page *)pmd_huge_pte(mm, pmdp);
+
/* FIFO */
- pgtable = pmd_huge_pte(mm, pmdp);
- if (list_empty(&pgtable->lru))
+ if (list_empty(&page->lru))
pmd_huge_pte(mm, pmdp) = NULL;
else {
- pmd_huge_pte(mm, pmdp) = list_entry(pgtable->lru.next,
- struct page, lru);
- list_del(&pgtable->lru);
+ pmd_huge_pte(mm, pmdp) = (pgtable_t) list_entry(page->lru.next,
+ struct page, lru);
+ list_del(&page->lru);
}
- return pgtable;
+
+ memset(&page->lru, 0, sizeof(page->lru));
+ return (pgtable_t)page;
}
#endif
--
2.5.0
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