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Re: [Xen-devel] [PATCH v2] mm/page_alloc: make bootscrub happen in idle-loop
- To: Jan Beulich <JBeulich@xxxxxxxx>, Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Thu, 8 Nov 2018 11:07:01 +0000
- Autocrypt: addr=andrew.cooper3@xxxxxxxxxx; prefer-encrypt=mutual; keydata= xsFNBFLhNn8BEADVhE+Hb8i0GV6mihnnr/uiQQdPF8kUoFzCOPXkf7jQ5sLYeJa0cQi6Penp VtiFYznTairnVsN5J+ujSTIb+OlMSJUWV4opS7WVNnxHbFTPYZVQ3erv7NKc2iVizCRZ2Kxn srM1oPXWRic8BIAdYOKOloF2300SL/bIpeD+x7h3w9B/qez7nOin5NzkxgFoaUeIal12pXSR Q354FKFoy6Vh96gc4VRqte3jw8mPuJQpfws+Pb+swvSf/i1q1+1I4jsRQQh2m6OTADHIqg2E ofTYAEh7R5HfPx0EXoEDMdRjOeKn8+vvkAwhviWXTHlG3R1QkbE5M/oywnZ83udJmi+lxjJ5 YhQ5IzomvJ16H0Bq+TLyVLO/VRksp1VR9HxCzItLNCS8PdpYYz5TC204ViycobYU65WMpzWe LFAGn8jSS25XIpqv0Y9k87dLbctKKA14Ifw2kq5OIVu2FuX+3i446JOa2vpCI9GcjCzi3oHV e00bzYiHMIl0FICrNJU0Kjho8pdo0m2uxkn6SYEpogAy9pnatUlO+erL4LqFUO7GXSdBRbw5 gNt25XTLdSFuZtMxkY3tq8MFss5QnjhehCVPEpE6y9ZjI4XB8ad1G4oBHVGK5LMsvg22PfMJ ISWFSHoF/B5+lHkCKWkFxZ0gZn33ju5n6/FOdEx4B8cMJt+cWwARAQABzSlBbmRyZXcgQ29v cGVyIDxhbmRyZXcuY29vcGVyM0BjaXRyaXguY29tPsLBegQTAQgAJAIbAwULCQgHAwUVCgkI CwUWAgMBAAIeAQIXgAUCWKD95wIZAQAKCRBlw/kGpdefoHbdD/9AIoR3k6fKl+RFiFpyAhvO 59ttDFI7nIAnlYngev2XUR3acFElJATHSDO0ju+hqWqAb8kVijXLops0gOfqt3VPZq9cuHlh IMDquatGLzAadfFx2eQYIYT+FYuMoPZy/aTUazmJIDVxP7L383grjIkn+7tAv+qeDfE+txL4 SAm1UHNvmdfgL2/lcmL3xRh7sub3nJilM93RWX1Pe5LBSDXO45uzCGEdst6uSlzYR/MEr+5Z JQQ32JV64zwvf/aKaagSQSQMYNX9JFgfZ3TKWC1KJQbX5ssoX/5hNLqxMcZV3TN7kU8I3kjK mPec9+1nECOjjJSO/h4P0sBZyIUGfguwzhEeGf4sMCuSEM4xjCnwiBwftR17sr0spYcOpqET ZGcAmyYcNjy6CYadNCnfR40vhhWuCfNCBzWnUW0lFoo12wb0YnzoOLjvfD6OL3JjIUJNOmJy RCsJ5IA/Iz33RhSVRmROu+TztwuThClw63g7+hoyewv7BemKyuU6FTVhjjW+XUWmS/FzknSi dAG+insr0746cTPpSkGl3KAXeWDGJzve7/SBBfyznWCMGaf8E2P1oOdIZRxHgWj0zNr1+ooF /PzgLPiCI4OMUttTlEKChgbUTQ+5o0P080JojqfXwbPAyumbaYcQNiH1/xYbJdOFSiBv9rpt TQTBLzDKXok86M7BTQRS4TZ/ARAAkgqudHsp+hd82UVkvgnlqZjzz2vyrYfz7bkPtXaGb9H4 Rfo7mQsEQavEBdWWjbga6eMnDqtu+FC+qeTGYebToxEyp2lKDSoAsvt8w82tIlP/EbmRbDVn 7bhjBlfRcFjVYw8uVDPptT0TV47vpoCVkTwcyb6OltJrvg/QzV9f07DJswuda1JH3/qvYu0p vjPnYvCq4NsqY2XSdAJ02HrdYPFtNyPEntu1n1KK+gJrstjtw7KsZ4ygXYrsm/oCBiVW/OgU g/XIlGErkrxe4vQvJyVwg6YH653YTX5hLLUEL1NS4TCo47RP+wi6y+TnuAL36UtK/uFyEuPy wwrDVcC4cIFhYSfsO0BumEI65yu7a8aHbGfq2lW251UcoU48Z27ZUUZd2Dr6O/n8poQHbaTd 6bJJSjzGGHZVbRP9UQ3lkmkmc0+XCHmj5WhwNNYjgbbmML7y0fsJT5RgvefAIFfHBg7fTY/i kBEimoUsTEQz+N4hbKwo1hULfVxDJStE4sbPhjbsPCrlXf6W9CxSyQ0qmZ2bXsLQYRj2xqd1 bpA+1o1j2N4/au1R/uSiUFjewJdT/LX1EklKDcQwpk06Af/N7VZtSfEJeRV04unbsKVXWZAk uAJyDDKN99ziC0Wz5kcPyVD1HNf8bgaqGDzrv3TfYjwqayRFcMf7xJaL9xXedMcAEQEAAcLB XwQYAQgACQUCUuE2fwIbDAAKCRBlw/kGpdefoG4XEACD1Qf/er8EA7g23HMxYWd3FXHThrVQ HgiGdk5Yh632vjOm9L4sd/GCEACVQKjsu98e8o3ysitFlznEns5EAAXEbITrgKWXDDUWGYxd pnjj2u+GkVdsOAGk0kxczX6s+VRBhpbBI2PWnOsRJgU2n10PZ3mZD4Xu9kU2IXYmuW+e5KCA vTArRUdCrAtIa1k01sPipPPw6dfxx2e5asy21YOytzxuWFfJTGnVxZZSCyLUO83sh6OZhJkk b9rxL9wPmpN/t2IPaEKoAc0FTQZS36wAMOXkBh24PQ9gaLJvfPKpNzGD8XWR5HHF0NLIJhgg 4ZlEXQ2fVp3XrtocHqhu4UZR4koCijgB8sB7Tb0GCpwK+C4UePdFLfhKyRdSXuvY3AHJd4CP 4JzW0Bzq/WXY3XMOzUTYApGQpnUpdOmuQSfpV9MQO+/jo7r6yPbxT7CwRS5dcQPzUiuHLK9i nvjREdh84qycnx0/6dDroYhp0DFv4udxuAvt1h4wGwTPRQZerSm4xaYegEFusyhbZrI0U9tJ B8WrhBLXDiYlyJT6zOV2yZFuW47VrLsjYnHwn27hmxTC/7tvG3euCklmkn9Sl9IAKFu29RSo d5bD8kMSCYsTqtTfT6W4A3qHGvIDta3ptLYpIAOD2sY3GYq2nf3Bbzx81wZK14JdDDHUX2Rs 6+ahAA==
- Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Julien Grall <julien.grall@xxxxxxx>, Wei Liu <wei.liu2@xxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxx
- Delivery-date: Thu, 08 Nov 2018 11:07:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Openpgp: preference=signencrypt
On 08/11/18 10:31, Jan Beulich wrote:
>>>> On 07.11.18 at 19:20, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 09/10/18 16:21, Sergey Dyasli wrote:
>>> Scrubbing RAM during boot may take a long time on machines with lots
>>> of RAM. Add 'idle' option to bootscrub which marks all pages dirty
>>> initially so they will eventually be scrubbed in idle-loop on every
>>> online CPU.
>>>
>>> It's guaranteed that the allocator will return scrubbed pages by doing
>>> eager scrubbing during allocation (unless MEMF_no_scrub was provided).
>>>
>>> Use the new 'idle' option as the default one.
>>>
>>> Signed-off-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
>> This patch reliably breaks boot, although its not immediately obvious how:
>>
>> (d9) (XEN) mcheck_poll: Machine check polling timer started.
>> (d9) (XEN) xenoprof: Initialization failed. Intel processor family 6 model
>> 60 is not supported
>> (d9) (XEN) Dom0 has maximum 400 PIRQs
>> (d9) (XEN) ----[ Xen-4.12-unstable x86_64 debug=y Not tainted ]----
>> (d9) (XEN) CPU: 0
>> (d9) (XEN) RIP: e008:[<ffff82d080440ddb>] setup.c#cmdline_cook+0x1d/0x77
>> (d9) (XEN) RFLAGS: 0000000000010282 CONTEXT: hypervisor
>> (d9) (XEN) rax: ffff82d080406bdc rbx: ffff8300c2c2c2c2 rcx:
>> 0000000000000000
>> (d9) (XEN) rdx: 00000007c7ffffff rsi: ffff83000045c24b rdi:
>> ffff83000045c24b
>> (d9) (XEN) rbp: ffff82d0804b7da8 rsp: ffff82d0804b7d98 r8:
>> ffff83003f057000
>> (d9) (XEN) r9: 7fffffffffffffff r10: 0000000000000000 r11:
>> 0000000000000001
>> (d9) (XEN) r12: ffff83003f0d8100 r13: 0000000000000000 r14:
>> ffff82d0805f33d0
>> (d9) (XEN) r15: 0000000000000002 cr0: 000000008005003b cr4:
>> 00000000001526e0
>> (d9) (XEN) cr3: 000000003fea7000 cr2: ffff8300c2c2c2c2
>> (d9) (XEN) fsb: 0000000000000000 gsb: 0000000000000000 gss:
>> 0000000000000000
>> (d9) (XEN) ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: e008
>> (d9) (XEN) Xen code around <ffff82d080440ddb>
>> (setup.c#cmdline_cook+0x1d/0x77):
>> (d9) (XEN) 05 5e fc ff 48 0f 44 d8 <80> 3b 20 75 09 48 83 c3 01 80 3b 20 74
>> f7 80 3d
>> (d9) (XEN) Xen stack trace from rsp=ffff82d0804b7d98:
>> [...]
>> (d9) (XEN) Xen call trace:
>> (d9) (XEN) [<ffff82d080440ddb>] setup.c#cmdline_cook+0x1d/0x77
>> (d9) (XEN) [<ffff82d080443b7f>] __start_xen+0x259c/0x292d
>> (d9) (XEN) [<ffff82d0802000f3>] __high_start+0x53/0x55
> That's apparently the 2nd cmdline_cook() invocation, when producing
> the Dom0 command line. I would suppose what "loader" points to has
> been scrubbed by the time we get there (with synchronous scrubbing
> APs wouldn't be able to get going with this before reaching
> heap_init_late()).
This is via a PVH boot (like a lot of my development work), and does
look to be a latent use-after-free. Dropping the VM down to a single
vcpu causes the problem to go away.
Sergey is kindly investigating.
~Andrew
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