Subject: Re: kvm splat in mmu_spte_clear_track_bits
To: Adam Borowski <kilobyte@angband.pl>,
        Paolo Bonzini <pbonzini@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        kvm <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20170820231302.s732zclznrqxwr46@angband.pl>
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 <20170821223228.edc6jrm7bpybtqlj@angband.pl>
 <1c270e76-05be-6f5f-29c6-9cb31f37f71d@redhat.com>
 <CANRm+Cyh6xs4c8Ed2yDFGbOeuyCohTO_+AUBdwM6co5Mkj1tXQ@mail.gmail.com>
 <20170825131419.r5lzm6oluauu65nx@angband.pl>
 <0a85df4b-ca0a-7e70-51dc-90bd1c460c85@redhat.com>
 <20170827123505.u4kb24kigjqwa2t2@angband.pl>
From: Bernhard Held <berny156@gmx.de>
Message-ID: <0dcca3a4-8ecd-0d05-489c-7f6d1ddb49a6@gmx.de>
Date: Mon, 28 Aug 2017 17:26:05 +0200
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On 08/27/2017 at 02:35 PM, Adam Borowski wrote:
> 4.13-rc5 retested fails
> Crashed only after two hours or so of testing.
> 
> 4.13-rc4 apparently works
> It survived several hours of varied tests (like 5 debian-installer runs, a
> win10 point release upgrade, some hurd package building, openbsd, etc),
> all while the host was likewise busy.
> 
> Thus: to the best of my knowledge, the problem is between 4.13-rc4 and 4.13-rc5
> but I wouldn't bet my life on it.

I get crashes with Win10 in kvm with 4.13-rc5. 4.13-rc4 works for me. THP seems to accelerate the crash, but that's not 100% sure.

There's still no crash after reverting merge 27df70 on 4.13-rc7. There are 21 commits in this merge, 10 are mm-related:

$ git log 4e082e9ba7cd..e86b298bebf7 --pretty=oneline --abbrev-commit
e86b298bebf7 userfaultfd: replace ENOSPC with ESRCH in case mm has gone during copy/zeropage
f357e345eef7 zram: rework copy of compressor name in comp_algorithm_store()
aac2fea94f7a rmap: do not call mmu_notifier_invalidate_page() under ptl
d041353dc98a mm: fix list corruptions on shmem shrinklist
af54aed94bf3 mm/balloon_compaction.c: don't zero ballooned pages
c0a6a5ae6b5d MAINTAINERS: copy virtio on balloon_compaction.c
b3a81d0841a9 mm: fix KSM data corruption
99baac21e458 mm: fix MADV_[FREE|DONTNEED] TLB flush miss problem
0a2dd266dd6b mm: make tlb_flush_pending global
56236a59556c mm: refactor TLB gathering API
a9b802500ebb Revert "mm: numa: defer TLB flush for THP migration as long as possible"
0a2c40487f3e mm: migrate: fix barriers around tlb_flush_pending
16af97dc5a89 mm: migrate: prevent racy access to tlb_flush_pending
9eeb52ae712e fault-inject: fix wrong should_fail() decision in task context
4e98ebe5f435 test_kmod: fix small memory leak on filesystem tests
9c56771316ef test_kmod: fix the lock in register_test_dev_kmod()
434b06ae23ba test_kmod: fix bug which allows negative values on two config options
a4afe8cdec16 test_kmod: fix spelling mistake: "EMTPY" -> "EMPTY"
5af10dfd0afc userfaultfd: hugetlbfs: remove superfluous page unlock in VM_SHARED case
75dddef32514 mm: ratelimit PFNs busy info message
d507e2ebd2c7 mm: fix global NR_SLAB_.*CLAIMABLE counter reads

Any hint on what to test first is welcome!

Bernhard