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Message-ID: <rar5bkfy7iplfhitsbna3b2dmxbk7nunlaiclwars6kffdetl4@lzm7iualliua>
Date: Tue, 25 Mar 2025 15:33:15 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: "Aithal, Srikanth" <sraithal@....com>
Cc: Linux-Next Mailing List <linux-next@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>, "Lendacky, Thomas" <Thomas.Lendacky@....com>,
"Roth, Michael" <Michael.Roth@....com>
Subject: Re: linux-next regression: SNP Guest boot hangs with certain cpu/mem
config combination
On Tue, Mar 25, 2025 at 02:40:00PM +0530, Aithal, Srikanth wrote:
> Hello,
>
>
> Starting linux-next build next-20250312, including recent build 20250324, we
> are seeing an issue where the SNP guest boot hangs at the "boot smp config"
> step:
>
>
> [ 2.294722] smp: Bringing up secondary CPUs ...
> [ 2.295211] smpboot: Parallel CPU startup disabled by the platform
> [ 2.309687] smpboot: x86: Booting SMP configuration:
> [ 2.310214] .... node #0, CPUs: #1 #2 #3 #4 #5 #6
> #7 #8 #9 #10 #11 #12 #13 #14 #15 #16 #17 #18 #19 #20 #21
> #22 #23 #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 #36
> #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47 #48 #49 #50 #51
> #52 #53 #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66
> #67 #68 #69 #70 #71 #72 #73 #74 #75 #76 #77 #78 #79 #80 #81
> #82 #83 #84 #85 #86 #87 #88 #89 #90 #91 #92 #93 #94 #95 #96
> #97 #98 #99 #100 #101 #102 #103 #104 #105 #106 #107 #108 #109 #110 #111
> #112 #113 #114 #115 #116 #117 #118 #119 #120 #121 #122 #123 #124 #125 #126
> #127 #128 #129 #130 #131 #132 #133 #134 #135 #136 #137 #138 #139 #140 #141
> #142 #143 #144 #145 #146 #147 #148 #149 #150 #151 #152 #153 #154 #155 #156
> #157 #158 #159 #160 #161 #162 #163 #164 #165 #166 #167 #168 #169 #170 #171
> #172 #173 #174 #175 #176 #177 #178 #179 #180 #181 #182 #183 #184 #185 #186
> #187 #188 #189 #190 #191 #192 #193 #194 #195 #196 #197 #198
> --> The guest hangs forever at this point.
>
>
> I have observed that certain vCPU and memory combinations work, while others
> do not. The VM configuration I am using does not have any NUMA nodes.
>
> vcpus Mem SNP guest boot
> <=240 19456M Boots fine
> >=241,<255 19456M Hangs
> 1-255 2048M Boots fine
> 1-255 4096M Boots fine
> >71 8192M Hangs
> >41 6144M Hangs
>
> When I bisected this issue, it pointed to the following commit :
>
>
> *commit 800f1059c99e2b39899bdc67a7593a7bea6375d8*
> Author: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Date: Mon Mar 10 10:28:55 2025 +0200
>
> mm/page_alloc: fix memory accept before watermarks gets initialized
Hm. It is puzzling for me. I don't see how this commit can cause the hang.
Could you track down where hang happens?
--
Kiryl Shutsemau / Kirill A. Shutemov
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