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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=uEIFfeil7ssJaBBmWiND1ItLKsRJcy4DAmF8CjtZoPI/WuyjzOd6Y1v3cTPpveuVv UOFr7zUgvX1dpfRXWXwgxD/+oxJVmazECRLFL8MmWeZ1QAVGHX8YC9I5Ynsa3rnWvz nIqJMTT1ibf/Y6p8ov3oRP2e91HaCdWzaguNav8U= Received: from pcnci.linuxbox.cz (pcnci.linuxbox.cz [10.76.3.14]) by linuxbox.linuxbox.cz (Sendmail) with ESMTPS id 69J8f1QH023969 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 19 Oct 2026 10:41:01 +0200 Received: from pcnci.linuxbox.cz (localhost [127.0.0.1]) by pcnci.linuxbox.cz (8.18.1/8.15.2) with ESMTPS id 69J8evSi3176760 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 19 Oct 2026 10:40:59 +0200 Date: Mon, 19 Oct 2026 10:40:57 +0200 From: Nikola Ciprich To: Andrew Morton Cc: Sean Christopherson , Borislav Petkov , David Laight , Rik van Riel , ljs@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@kernel.org, Mike Rapoport , Dave Hansen , Pedro Falcato , Kiryl Shutsemau , luizcap@redhat.com, pbonzini@redhat.com, Tal Zussman , Matt Fleming , Nikola Ciprich Subject: Re: hunting memory corruption bug in 6.18.x Message-ID: References: <20261009090042.39ba9c06@pumpkin> <20261014235736.GCatAW8GD0GlYumL4l@fat_crate.local> <20261015172820.7961d2c0def74d41cc6c4b0c@linux-foundation.org> <20261016031242.GDatGWKo98YSOhEOOn@fat_crate.local> <20261015211832.45d87fab15bb3e0bbc2f47cb@linux-foundation.org> <20261016054954.GEatG7AgMNFRkiTo1H@fat_crate.local> <20261018201538.d0957878f378a9821852836f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261018201538.d0957878f378a9821852836f@linux-foundation.org> X-Scanned-By: MIMEDefang 3.7.1 on 10.76.66.3 X-Scanned-By: MIMEDefang v3.7.1/SpamAssassin v4.000002 on lbxovapx9 (nik) X-Scanned-By: MIMEDefang 2.86 on 10.76.66.10 X-Antivirus: on lbxovapx9 by Antivirus X-Milter-Copy-Status: O X-Rspam-User: X-Rspamd-Queue-Id: 8D6A340007 X-Rspamd-Server: rspam08 X-Stat-Signature: 35mep7w9xnsprinia1yzohsdt3b98mz8 X-HE-Tag: 1792399280-833328 X-HE-Meta: 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 vIc/DIxx nDFlprhaqzYea2k9Yu86j0OhDaDGncBZPBuypvzlYUMbN9W+euWrC6CM2MAS1scXLRDcRqfomkJkLHEsThv4ECHKS6vijfHKHdmSKIt/Qo7ZOOKR97Z0Vhc9/tF2yg/k8FhyveqoVxml57DkC9z4rUIdyL7KxRIVvq5lyRxdoBMyEHNT2/Q4YpDAyDMxYe4Jbm8WQcmnVVXNPqQy1iQuKC9ZN0TFwInEFdHS4ncZK+ARVQrZFdHLHDGYf96MzJs//tCWx+/kSMcfE/epeHehdpZUWfGuOrTdTYbemeY2gKQn/wc4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Well we initially thought that nested virtualization was not involved. > > It it indeed is in the picture then it might have been 55780d8a1dcc > which unknowingly fixed this. > > Are you able to test that commit on the 6.18 kernel? Sure! And I have more good news: after applying 55780d8a1dcc to 6.18.56, I was able to perform more than 30 migrations without a glitch. After booting back into 6.18.56 without it, both VMs crashed within 2-3 migrations. Furthermore, some memory apparently got corrupted on one of the hosts, since various commands started crashing too: [ 303.466091] traps: systemd-logind[3085] trap invalid opcode ip:7f7b5667e616 sp:7ffe1afdec38 error:0 in libsystemd-shared-252.so[7e616,7f7b5666d000+22e000] [ 303.493810] traps: systemd-coredum[11269] trap invalid opcode ip:7fc6bf67f614 sp:7ffc075da958 error:0 in libsystemd-shared-252.so[7f614,7fc6bf66d000+22e000] [ 377.528955] traps: systemd[5607] trap invalid opcode ip:7f791447e616 sp:7ffe83e61cf8 error:0 in libsystemd-shared-252.so[7e616,7f791446d000+22e000] [ 377.556993] traps: systemd-coredum[12080] trap invalid opcode ip:7f97ce07f614 sp:7ffe28b56a88 error:0 in libsystemd-shared-252.so[7f614,7f97ce06d000+22e000] [ 3746.173043] traps: hostnamectl[45846] trap invalid opcode ip:7fe00cc7f614 sp:7fff89916e48 error:0 in libsystemd-shared-252.so[7f614,7fe00cc6d000+22e000] [ 3746.202305] traps: systemd-coredum[45847] trap invalid opcode ip:7f7fe9e7f614 sp:7ffea227cfa8 error:0 in libsystemd-shared-252.so[7f614,7f7fe9e6d000+22e000] [ 3750.581940] traps: systemctl[45903] trap invalid opcode ip:7fbb8967f614 sp:7fff733e5748 error:0 in libsystemd-shared-252.so[7f614,7fbb8966d000+22e000] [ 3750.612651] traps: systemd-coredum[45904] trap invalid opcode ip:7f90d347f614 sp:7ffdc7f55148 error:0 in libsystemd-shared-252.so[7f614,7f90d346d000+22e000] I'm not sure if this is of any use, but I collected a vmcore of this state by intentionally crashing the host via /proc/sysrq-trigger. Anyway, I'll give 55780d8a1dcc some more migration rounds, but it looks promising. I'll report soon Cheers, nik