advice on bad_page instance

[Luigi Semenzato <semenzato@google.com>]

We are seeing several instances of these things (often with different
but plausible values in the struct page) in kernel 3.8.11, followed by
a panic() in release_pages a few seconds later.

I realize it's an old kernel and probably of little interest here, but
I would be most grateful for any pointers on how to proceed.  In
particular, I suspect that many such bugs may have been fixed by now,
but I am not sure how to find the right fix (which I would backport).

Also, this happens under heavy swap, and we're using zram.  I wonder
if there may be a race condition related to zram which may have been
fixed since then, and which may result in these symptoms.

Many thanks for any pointer!

Luigi

<1>[ 5392.106074] BUG: Bad page state in process CompositorTileW  pfn:57a7e
<1>[ 5392.106109] page:ffffea00015e9f80 count:0 mapcount:0 mapping:
      (null) index:0x2
<1>[ 5392.106122] page flags: 0x4000000000000004(referenced)
<5>[ 5392.106139] Modules linked in: i2c_dev uinput
snd_hda_codec_realtek memconsole snd_hda_codec_hdmi uvcvideo
videobuf2_vmalloc videobuf2_memops videobuf2_core videodev
snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_timer
zram(C) lzo_compress zsmalloc(C) fuse nf_conntrack_ipv6 nf_defrag_ipv6
ip6table_filter ip6_tables ath9k_btcoex ath9k_common_btcoex
ath9k_hw_btcoex ath mac80211 cfg80211 option usb_wwan cdc_ether usbnet
ath3k btusb bluetooth joydev ppp_async ppp_generic slhc tun
<5>[ 5392.106333] Pid: 27363, comm: CompositorTileW Tainted: G    B
C   3.8.11 #1
<5>[ 5392.106344] Call Trace:
<5>[ 5392.106357]  [<ffffffff978ba5bb>] bad_page+0xcf/0xe3
<5>[ 5392.106370]  [<ffffffff978bb181>] get_page_from_freelist+0x21a/0x46c
<5>[ 5392.106383]  [<ffffffff978beb74>] ? release_pages+0x19b/0x1be
<5>[ 5392.106394]  [<ffffffff978bb5da>] __alloc_pages_nodemask+0x207/0x685
<5>[ 5392.106407]  [<ffffffff97cb8caf>] ? _cond_resched+0xe/0x1e
<5>[ 5392.106421]  [<ffffffff978d215a>] handle_pte_fault+0x305/0x500
<5>[ 5392.106433]  [<ffffffff978d4f5e>] ? __vma_link_file+0x65/0x67
<5>[ 5392.106445]  [<ffffffff978d30d0>] handle_mm_fault+0x97/0xbb
<5>[ 5392.106459]  [<ffffffff97828616>] __do_page_fault+0x1d4/0x38c
<5>[ 5392.106470]  [<ffffffff978d7803>] ? do_mmap_pgoff+0x284/0x2c0
<5>[ 5392.106482]  [<ffffffff978ca82c>] ? vm_mmap_pgoff+0x7d/0x8e
<5>[ 5392.106495]  [<ffffffff97828800>] do_page_fault+0xe/0x10
<5>[ 5392.106506]  [<ffffffff97cb9d32>] page_fault+0x22/0x30

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