From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E85FD3446CE; Wed, 10 Jun 2026 17:06:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781111188; cv=none; b=uZbDYS6Afg1WzB+qQnrX50KUnQyu9mwqsCBACNHYv0x2jBR8Gq2082kvOWI3WcIrmGkaB6WFbSLm+FzJ8rFL/BUApwXn0y+jI5t5RxX9UsnGQ2iwT6HZ1gX98ogr8ri7Z6K8eDS0FIb4yIDubis7/3+mUFCRzW+yWKBnkagb9ag= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781111188; c=relaxed/simple; bh=7cgMsRQUBojA6Mva2ZYVvWsCGdM3/e+cNfzD10dDeio=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=O0O574IL3OROmNQehoNIh9SYHeSKZp9CwbaT1kbLHHdpxcZRvofDSW+1QsL7h7CXWQK31S96TQm8vdiATfDOhC/XsoTwfPNrP6MnfcjqhHi7a7YtGFIdYdld/hxHp54m1Sd1jOVezSIDBZnZTWluRd7NWGxoS6pMUmYVn2WMqYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TGSs4LCL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TGSs4LCL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FFF01F00899; Wed, 10 Jun 2026 17:06:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781111187; bh=Z8ruKHHrlEYrpu6Cn+yWVJnDZPbAYpa+QMkhGoRxhLo=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=TGSs4LCLc9Tt+HNdxZVSF53FXJm0UzAvGMlASAfrx4rkXD4BGMpJmxYRLMx0TH3Qg s7oB89jH3m4YmSmOZCmvomhXijjGG2HjVrzRg77QaDPH5/nrNjpaqtS9ykghiAinPL slTNidno5EmOfXguS9dZIpl5iET/UtC6LnqhK5x3do5rkCLJt2N/aqjYQqnc8qe44T wzzFIjhkwu43bFo3Tv+hebG+jA6k+ivLgH1WjPlaLFCFTHc+bS9uRNtU/q47+Yp1C6 a6SCQB/qCmKBnBs1+fCYOOQR/KEWGHDTkkGh+eifD5te8tCGPyDnsKfExIeJgeSOrK SzlB3gv8RnVpw== From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 4/5] KVM: s390: vsie: Add missing radix_tree_preload() in _gaccess_shadow_fault() Reply-To: sashiko-reviews@lists.linux.dev To: "Claudio Imbrenda" Cc: "Heiko Carstens" , kvm@vger.kernel.org, "Alexander Gordeev" , linux-s390@vger.kernel.org, "Vasily Gorbik" In-Reply-To: <20260610165247.238366-5-imbrenda@linux.ibm.com> References: <20260610165247.238366-5-imbrenda@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 10 Jun 2026 17:06:26 +0000 Message-Id: <20260610170627.2FFF01F00899@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] Ignoring the return value of radix_tree_preload() causes an unbala= nced unlock and preempt count underflow if preloading fails. -- commit c5536624d068cf6e0fec6f8851a47bfb6f4371b3 Author: Claudio Imbrenda KVM: s390: vsie: Add missing radix_tree_preload() in _gaccess_shadow_fault() This commit adds a missing radix_tree_preload() to _gaccess_shadow_fault() to guarantee forward progress. It also splits the core of the function into ___gaccess_shadow_fault() to simplify locking. CC: stable@vger.kernel.org # 7.1 > diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c > index 20e28b183c1ac..c072b6872bf8b 100644 > --- a/arch/s390/kvm/gaccess.c > +++ b/arch/s390/kvm/gaccess.c [ ... ] > @@ -1582,35 +1582,46 @@ static int _gaccess_do_shadow(struct kvm_s390_mmu= _cache *mc, struct gmap *sg, [ ... ] > static inline int _gaccess_shadow_fault(struct kvm_vcpu *vcpu, struct gm= ap *sg, gpa_t saddr, > unsigned long seq, struct pgtwalk *walk) > { > int rc; > =20 > if (kvm_s390_array_needs_retry_unsafe(vcpu->kvm, seq, walk->raw_entries= )) > return -EAGAIN; > rc =3D kvm_s390_mmu_cache_topup(vcpu->arch.mc); > if (rc) > return rc; > + > + do { > + radix_tree_preload(GFP_KERNEL); > + scoped_guard(read_lock, &vcpu->kvm->mmu_lock) > + rc =3D ___gaccess_shadow_fault(vcpu, sg, saddr, seq, walk); > + radix_tree_preload_end(); [Severity: High] Does this code handle radix_tree_preload() allocation failures correctly? radix_tree_preload() can return -ENOMEM under memory pressure. When it fail= s, it returns without disabling preemption or acquiring the local lock. Since the return value is ignored here, radix_tree_preload_end() is unconditionally called at the end of the loop iteration. Could this result in an unbalanced unlock and preempt count underflow if the preload fails? > + } while (rc =3D=3D -ENOMEM); > + > return rc; > } --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260610165247.2383= 66-1-imbrenda@linux.ibm.com?part=3D4