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.
Cc: sta...@vger.kernel.org
Signed-off-by: Mel Gorman <mgor...@suse.de>
Reported-by: Jovi Zhangwei <j...@cloudflare.com>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ffeaa4105e48..c2980e8733bc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2181,7 +2181,7 @@ void task_numa_work(struct callback_head *work)
}
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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