| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.0 093/105] sched, numa: do not hint for NUMA balancing on VM_MIXEDMAP mappings | Date | Fri, 19 Jun 2015 13:36:23 -0700 |
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4.0-stable review patch. If anyone has any objections, please let me know.
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From: Mel Gorman <mgorman@suse.de>
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@suse.de> Reported-by: Jovi Zhangwei <jovi@cloudflare.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2166,7 +2166,7 @@ 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; }
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