From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792427924; b=g6+2s72/LffrKi0zrngBWO1VGqRKW9y1tkymjyTVI+1XCl8KB29LEyy09+aOxgNCon7W vW7u9s2tj8ZcgHzr1gqtDxKT/8IzdmkcmoH9RJ4aAmRH0v14DN027ya9fjIEDujSBlC7v EA5SEPXgEgHWNLi86gOP5abIC7vCA17J/4FTvinOGmROW65YGF64yv3XgmrOxSP/ffG0/ cCU4NzDZEFBP2SrIM6vJdxuZ0pru9IjPpua7hfE7EaWwRDursGnrh1/7MMKApAZEyvlEN HiIhcyCsSeJn5TnX6+Fi+AO6+Y9hL7B8zNfoBTXrInzTNydfPoHzCemM+br+ZHPOJlw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792427924; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition: Content-Transfer-Encoding:In-Reply-To; bh=782DsQAc3PyqP86rwUshH6wFfstxk+d0IqNd3tGjmLM=; b=FLimXclqiMmoeC78AWwVlItNriy0dSG2dM2ZgrbL76rrVpGPk4xf95aeTCQ58tzbrnr3 nLqXIsMSbi2Bgjja8tn9giWF6xm5OxJT4ZvsgR4yMyWCgcoMQAIp+b1SeI3Qa/CO/D248 VFhs2p/vRAyPThLzqR1Sw2B3NSQeInUtf4dS8AwuyIjmsiSRE+A8Tf91B7Gcj9MiCODiT LBmPPZz8wMilTECOgZUj8KVIFPkxWuu13k60sAmT705GDMPqnHVxP1PtWkfSy2NRrcmNi upaTdMj/OCYWQrujoCP2lV+WqA1Z7ZlsCHAmfgucae+R0ghpbsTtZ+ask8YGh4n3MXw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QBRYFQz5; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EEE32606A31C for ; Mon, 19 Oct 2026 16:38:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QBRYFQz5 Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE1041F000C4; Mon, 19 Oct 2026 16:38:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792427923; bh=782DsQAc3PyqP86rwUshH6wFfstxk+d0IqNd3tGjmLM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=QBRYFQz5RTCmVbvuVbgrR2TdBhZPz21zHiCpfBbQ/2P+18ztTuSIwWEN7fYxYK7Go 2r0/1F5w1jdvDFBaJfn2Idama23UR+CceHtAKtV4lhy2qc6XE6yaDx4s223npvokb3 ceYc6aYzP8nV1pVgNqT+RCPhpX9Z3jYTUOj/S9ee2rlIBT1MlWAQH2D0RQhTNzhU5L nE+30paIAZr30qyAzEFaiIIsVNhvuC/GjPL9diq/bHKKumMlblrLS2+yfe8ve6qbl1 jTbHjnWViWqsQJGDf1hyuA99Ky2aDigW+SDvSSihAfC849JCTGlMaRhiyT7rgSuObU q+vmqhOBgSofA== Date: Mon, 19 Oct 2026 17:38:37 +0100 From: "Lorenzo Stoakes (ARM)" To: Andrew Morton Cc: Nikola Ciprich , Sean Christopherson , Borislav Petkov , David Laight , Rik van Riel , 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 , Yosry Ahmed Subject: Re: hunting memory corruption bug in 6.18.x Message-ID: References: <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> <20261019083529.a81910ac0976c1a5687d4c6a@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: <20261019083529.a81910ac0976c1a5687d4c6a@linux-foundation.org> On Mon, Oct 19, 2026 at 08:35:29AM -0700, Andrew Morton wrote: > On Mon, 19 Oct 2026 17:22:37 +0200 Nikola Ciprich wrote: > > > > > > > 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. > > Great, thanks. > > oops, we haven't been cc'ing Yosry. > > > Definitely a -stable candidate. Andrew, will you send it to Greg, or shall I? > > I volunteer Yosry or Sean ;) > > I think 55780d8a1dcc should be repackaged before sending over to the > -stable people. Its changelog is very wrong: "The bug is benign > though". Update the changelog to explain that the bug is in fact evil. > Otherwise -stable and further downstream won't understand why we sent > it to them and won't understand the impact. > > And that repackaging would be an opportunity to add > Reported-by:/Closes:/Tested-by: you, which is the least we can do to > thank you for all this diligent work! > Very happy to see this tracked down :) thanks to everybody else who got stuck in after me! -- Cheers, Lorenzo