* akpm@xxxxxxxxxxxxxxxxxxxx <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> From: Mel Gorman <mgorman@xxxxxxx>
> Subject: sched, numa: do not hint for NUMA balancing on VM_MIXEDMAP mappings
>
> 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
> --- a/kernel/sched/fair.c~sched-numa-do-not-hint-for-numa-balancing-on-vm_mixedmap-mappings
> +++ a/kernel/sched/fair.c
> @@ -2181,7 +2181,7 @@ void task_numa_work(struct callback_head
> }
> for (; vma; vma = vma->vm_next) {
> if (!vma_migratable(vma) || !vma_policy_mof(vma) ||
> - is_vm_hugetlb_page(vma)) {
> + is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_MIXEDMAP)) {
> continue;
> }
the fix looks good to me, but this should really be done in a bit cleaner fashion,
by breaking out an vma_numa_migratable() inline helper or so? Anyway:
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Thanks,
Ingo
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