From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=62.245.111.132 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792423411; b=Bxvh/EGbtuNtBAz1i96ilTh87Pu5iliZqCHk4sz556Fq6+5j0/i1klfz0VjAzfBPI8+v D18nlo34z/44bQ2BJJg7d57ZjTO1431fxTCgPf6tnjCDyWvRQT+cdVKwAMYE7I2dP8lD0 vlOongFXVsu2b/bHlmE6pOfwEBJQt9C+gwxPNCOv632AquPIbYT7o7gLCnuTVKwXCOYOG tGy6P93vFwlmGgdt9wtcZF1MJGyeQuz31I2AFxfNsbH4sxJ1zrGjV+Ry+UpCW4G9+Du4S Ud5UfZAdeQdDycNoFcdTI3hDx2YpbaklHBYn2CZVeM+4Dkm9w08c1ZSsX11cvz/BN3w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792423411; h=DMARC-Filter:Received:DKIM-Filter:DKIM-Signature:Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:Content-Transfer-Encoding: In-Reply-To:X-Scanned-By:X-Scanned-By:X-Scanned-By:X-Antivirus: X-Spam-Score:X-Milter-Copy-Status; bh=+HvJ2kFVuvGS7ZT5+hoLkozBmLJcLaDkGg+Rc7WYWmE=; b=o72ZooLDBJb6PLtMtdX/zS6nEu9F2jjVCS9hsD9nHETCavrQrj5W5HbzbZjE7FvapICu XuGrOrr5oU4MMPSw2DbwymFGjXdp5dDHPZtwyTdUM+wIDfJ14Pf+9mZ/Ml6n1hTpWljNA /M89wSRcJ6K6GJ78Dt9ur2LdHSDI1nKfVnCfnVLufIC3dvOzeEnmmyrwMZrrz397ArDdK yKa/eYkataAEB/fQnL5x2DiblZGb/yIPH4kReCOa4lHyf7JOQx9SaAasfbtzVzRYTYnP1 i8PuLNBl8cCRHn3OBsi3wR7K+D3sSwPTcdEUeyJ3h2UUdloAnbrMAeMqypta5Q5yAwg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linuxbox.cz; spf=pass smtp.mailfrom=linuxbox.cz; dkim=pass header.d=linuxbox.cz header.i=@linuxbox.cz header.a=rsa-sha256 header.s=default header.b=Hh5PLXpv; arc=none smtp.remote-ip=62.245.111.132 Received: from gwu.lbox.cz (gwu.lbox.cz [62.245.111.132]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E36260ACCC9 for ; Mon, 19 Oct 2026 15:23:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9E36260ACCC9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linuxbox.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linuxbox.cz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxbox.cz header.i=@linuxbox.cz header.a=rsa-sha256 header.s=default header.b=Hh5PLXpv Received: from linuxbox.linuxbox.cz (linuxbox.linuxbox.cz [10.76.66.10]) by gwu.lbox.cz (Sendmail) with ESMTPS id 69JFMfLC1208580 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 19 Oct 2026 17:22:41 +0200 DKIM-Filter: OpenDKIM Filter v2.11.0 gwu.lbox.cz 69JFMfLC1208580 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxbox.cz; s=default; t=1792423362; bh=+HvJ2kFVuvGS7ZT5+hoLkozBmLJcLaDkGg+Rc7WYWmE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Hh5PLXpv5/rcoN0VZaOLprddInBoOxdrtKPj8uYQo+VzSQcyZAU2ZNQ3Kqt2My1qX /520Dy+VoiNeqPY5l/1x2zlBC6dLkRDxm6cGczTHN8N8Gr4biMl9ZkZKfHFtPNJR/M AxZd75YD1uEaQr1hKEINql/b/YbZC2nZett8lwHI= Received: from pcnci.linuxbox.cz (pcnci.linuxbox.cz [10.76.3.14]) by linuxbox.linuxbox.cz (Sendmail) with ESMTPS id 69JFMeGg012171 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 19 Oct 2026 17:22:40 +0200 Received: from pcnci.linuxbox.cz (localhost [127.0.0.1]) by pcnci.linuxbox.cz (8.18.1/8.15.2) with ESMTPS id 69JFMbH63191394 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 19 Oct 2026 17:22:39 +0200 Date: Mon, 19 Oct 2026 17:22:37 +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: <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> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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-Spam-Score: N/A (trusted relay) X-Milter-Copy-Status: O > > 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. 500+ migrations back and forth, no issues. I consider this solved and am rolling out the patched kernel; I’ll report if anything new turns up. Definitely a -stable candidate. Andrew, will you send it to Greg, or shall I? Thank you all for spending time on this! BR nik > > I'll report soon > > Cheers, nik > -- Ing. Nikola CIPRICH technický ředitel +420 591 166 214 +420 777 093 799 nikola.ciprich@linuxbox.cz www.linuxbox.cz