Michal Hocko <mhocko@xxxxxxx> writes:
> On Mon 28-05-12 20:51:30, Aneesh Kumar K.V wrote:
>> 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
>
> This should be part of the changelog.
I was expecting the patch to be folded back to the existing patch in
-mm. That is the reason I added stack trace in the notes section so that
if we decided to keep it as a separate patch we can pull the stack trace
and add it to commit message.
>
>>
>>
>> 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);
>
> I guess you want hpage->flags here.
Existing code pass the flag details of the page passed as the
argument. I didn't want to change that.
-aneesh
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