On Tue, Jun 16, 2015 at 03:12:01PM -0700, Jovi Zhangwei wrote:
> commit 8e76d4eecf7afeec9328e21cd5880e281838d0d6 upstream.
>
> Jovi Zhangwei reported the following problem
>
> Below kernel vm bug can be triggered by tcpdump which mmaped a lot of pages
> with GFP_COMP flag.
>
> [Mon May 25 05:29:33 2015] page:ffffea0015414000 count:66 mapcount:1 mapping:
> (null) index:0x0
> [Mon May 25 05:29:33 2015] flags: 0x20047580004000(head)
> [Mon May 25 05:29:33 2015] page dumped because: VM_BUG_ON_PAGE(compound_order
> (page) && !PageTransHuge(page))
> [Mon May 25 05:29:33 2015] ------------[ cut here ]------------
> [Mon May 25 05:29:33 2015] kernel BUG at mm/migrate.c:1661!
> [Mon May 25 05:29:33 2015] invalid opcode: 0000 [#1] SMP
>
> In this case it was triggered by running tcpdump but it's not necessary
> reproducible on all systems.
>
> sudo tcpdump -i bond0.100 'tcp port 4242' -c 100000000000 -w 4242.pcap
>
> Compound pages cannot be migrated and it was not expected that such pages
> be marked for NUMA balancing. This did not take into account that drivers
> such as net/packet/af_packet.c may insert compound pages into userspace
> with vm_insert_page. This patch tells the NUMA balancing protection
> scanner to skip all VM_MIXEDMAP mappings which avoids the possibility that
> compound pages are marked for migration.
>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
> [jovi: Backported to 3.18: adjust context]
> Signed-off-by: Jovi Zhangwei <jovi@xxxxxxxxxxxxxx>
> Reported-by: Jovi Zhangwei <jovi@xxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> ---
> kernel/sched/fair.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index ef2b104..2246a36 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1979,8 +1979,10 @@ void task_numa_work(struct callback_head *work)
> vma = mm->mmap;
> }
> for (; vma; vma = vma->vm_next) {
> - if (!vma_migratable(vma) || !vma_policy_mof(vma))
> + if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
> + is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
> continue;
> + }
Patch is corrupted :(
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