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author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-01-04 15:19:42 +0100 |
---|---|---|
committer | Sasha Levin <sashal@kernel.org> | 2019-01-09 20:20:47 +0100 |
commit | da8ced360ca8ad72d8f41f5c8fcd5b0e63e1555f (patch) | |
tree | 0ed4f5ccc9d4200b8a9e4b91e6235ba002ec097b /security/yama/Makefile | |
parent | Drivers: hv: vmbus: Check for ring when getting debug info (diff) | |
download | linux-da8ced360ca8ad72d8f41f5c8fcd5b0e63e1555f.tar.xz linux-da8ced360ca8ad72d8f41f5c8fcd5b0e63e1555f.zip |
hv_balloon: avoid touching uninitialized struct page during tail onlining
Hyper-V memory hotplug protocol has 2M granularity and in Linux x86 we use
128M. To deal with it we implement partial section onlining by registering
custom page onlining callback (hv_online_page()). Later, when more memory
arrives we try to online the 'tail' (see hv_bring_pgs_online()).
It was found that in some cases this 'tail' onlining causes issues:
BUG: Bad page state in process kworker/0:2 pfn:109e3a
page:ffffe08344278e80 count:0 mapcount:1 mapping:0000000000000000 index:0x0
flags: 0xfffff80000000()
raw: 000fffff80000000 dead000000000100 dead000000000200 0000000000000000
raw: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
page dumped because: nonzero mapcount
...
Workqueue: events hot_add_req [hv_balloon]
Call Trace:
dump_stack+0x5c/0x80
bad_page.cold.112+0x7f/0xb2
free_pcppages_bulk+0x4b8/0x690
free_unref_page+0x54/0x70
hv_page_online_one+0x5c/0x80 [hv_balloon]
hot_add_req.cold.24+0x182/0x835 [hv_balloon]
...
Turns out that we now have deferred struct page initialization for memory
hotplug so e.g. memory_block_action() in drivers/base/memory.c does
pages_correctly_probed() check and in that check it avoids inspecting
struct pages and checks sections instead. But in Hyper-V balloon driver we
do PageReserved(pfn_to_page()) check and this is now wrong.
Switch to checking online_section_nr() instead.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'security/yama/Makefile')
0 files changed, 0 insertions, 0 deletions