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 3DEE943A7E9 for ; Thu, 27 Aug 2026 11:17:09 +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=1787829435; cv=none; b=iESyLU+61+mdY1ux8OlldYLg+4GAvNVXxY/gGWLgzamWAczGQ/p1MeGKCwHPMj3hkgkD9EdouiPOJWLn6w/+w1PPLfeb0SZF9dUD1Sf2HWDOR9gnhjWQEOyznM0Z86Z0qY0k2zw/4/YVaExWLxoJR30FJ1KG8j1DvJ4m4XR3bqU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787829435; c=relaxed/simple; bh=P+n7t1lgDLepCUh6QK0CJBLUoi/QVnmD37Pp3bbMScU=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=oLfH8Xz4wIwkk9TQjEkcnRLAicQD0kwZ8wEc2byGgZW4MvQ/2GqLJ/udq99BjUYCyFpoJ57YsFWdvBkQfzMV/7EogY6ewJfkKes424sYRXGUm5FOiyCsMZiu+CrTF/vUEHgAHbPMEj6chxNNyf4oZKgdJti5IsA8e+7fy2zb33A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VmoPHhsZ; 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="VmoPHhsZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 860791F000E9; Thu, 27 Aug 2026 11:17:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787829425; bh=mCgiuu9Tc7EirM0QmHma2GvPOcCRqwf+MFqZ84T4WhE=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=VmoPHhsZBbleqko8zyQvhjUus2VexBVdg72lf+Xw5MerOaxveGi2S0WYucRRHUDb3 o7r+CH1Kr/UhXaUteCWLZXicl+nSYBb7TOvAzGbYnGT4kd/za1eZlebiLvfH+krNgu TG6UJSXRMFvgzIPGA2hebdb+pk5W/acWs8s9RlCQ4D59NfCfrJNh6gIlVmJgMl+nFp SknYTKHN+BVbQyNS12hONG/ZpRvEGYRICIvBrfblrBru2kJxYv67PaDZpknhAXYmTj 0IreM530LviEMJHSbmA+bWYKLz5ZACrEZwJ8StCSYHfzZa/PlvK9+43vgh34e+IGc0 yxq1gVIngCU7Q== From: sashiko-bot@kernel.org Subject: Re: [PATCH] KVM: Release reserved xarray entries if reserving memory attributes fails Reply-To: sashiko-reviews@lists.linux.dev To: "Zeng Chi" Cc: kvm@vger.kernel.org In-Reply-To: <20260827110558.457891-1-zeng_chi911@163.com> References: <20260827110558.457891-1-zeng_chi911@163.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 27 Aug 2026 11:17:05 +0000 Message-Id: <20260827111705.860791F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@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] The error cleanup loop in `kvm_vm_set_mem_attributes` lacks a `con= d_resched()` call, which can cause CPU soft lockups when reverting a massiv= e memory range. -- commit 628b8d791b455e8fdc196cf53b9e1f82e2d7fdb6 Author: Zeng Chi KVM: Release reserved xarray entries if reserving memory attributes fails This commit fixes a memory leak in kvm_vm_set_mem_attributes() where previo= usly reserved xarray entries were left behind if a subsequent reservation failed= . It adds a backward loop to release the successfully reserved entries before ba= iling out on the error path. > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2575,8 +2575,11 @@ static int kvm_vm_set_mem_attributes(struct kvm *k= vm, gfn_t start, gfn_t end, > */ > for (i =3D start; i < end; i++) { > r =3D xa_reserve(&kvm->mem_attr_array, i, GFP_KERNEL_ACCOUNT); > - if (r) > + if (r) { > + while (i-- > start) > + xa_release(&kvm->mem_attr_array, i); [Severity: High] Can this backward cleanup loop cause CPU soft lockups if a massive memory range was requested? The forward loop correctly yields the CPU via cond_resched() to handle large ranges, but the unwinding error path does not.=20 If userspace invokes KVM_SET_MEMORY_ATTRIBUTES on a massive range and xa_reserve() eventually fails, this loop will continuously process potentia= lly millions of entries. On kernels with CONFIG_PREEMPT_VOLUNTARY or CONFIG_PREEMPT_NONE, could this block scheduling long enough to trigger the soft lockup watchdog? > goto out_unlock; > + } > =20 > cond_resched(); > } --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260827110558.4578= 91-1-zeng_chi911@163.com?part=3D1