From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
The change was introduced by "hugetlb: simplify migrate_huge_page() "
We should use compound page head instead of tail pages in
migrate_huge_page().
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
This is an important bug fix. If we want we can fold it with the not
yet merged upstream patch mentioned above in linux-next. The stack
trace for the crash is
[ 75.337421] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
[ 75.338386] IP: [<ffffffff816b3f0f>] __mutex_lock_common+0xa1/0x350
[ 75.338386] PGD 1d700067 PUD 1d7dd067 PMD 0
[ 75.338386] Oops: 0002 [#1] SMP
[ 75.338386] CPU 1
[ 75.338386] Modules linked in:
...
...
[ 75.338386] Call Trace:
[ 75.338386] [<ffffffff810ffc04>] ? try_to_unmap_file+0x38/0x51c
[ 75.338386] [<ffffffff810ffc04>] ? try_to_unmap_file+0x38/0x51c
[ 75.338386] [<ffffffff813b5f8b>] ? vsnprintf+0x83/0x421
[ 75.338386] [<ffffffff816b427d>] mutex_lock_nested+0x2a/0x31
[ 75.338386] [<ffffffff8110999b>] ? alloc_huge_page_node+0x1d/0x55
[ 75.338386] [<ffffffff810ffc04>] try_to_unmap_file+0x38/0x51c
[ 75.338386] [<ffffffff8110999b>] ? alloc_huge_page_node+0x1d/0x55
[ 75.338386] [<ffffffff810a06b9>] ? arch_local_irq_save+0x9/0xc
[ 75.338386] [<ffffffff816b5e3b>] ? _raw_spin_unlock+0x23/0x27
[ 75.338386] [<ffffffff81100839>] try_to_unmap+0x25/0x3c
[ 75.338386] [<ffffffff810641c2>] ? console_unlock+0x210/0x238
[ 75.338386] [<ffffffff811141e3>] migrate_huge_page+0x8d/0x178
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 4a45098..53a1495 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1428,8 +1428,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
}
/* Keep page count to indicate a given hugepage is isolated. */
- ret = migrate_huge_page(page, new_page, MPOL_MF_MOVE_ALL, 0, true);
- put_page(page);
+ ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, 0, true);
+ put_page(hpage);
if (ret) {
pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
--
1.7.10
--
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