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Tue, 8 Sep 2026 09:55:27 +0000 (GMT) Message-ID: <490a5c66-c415-42c6-883e-1927d9517322@linux.ibm.com> Date: Tue, 8 Sep 2026 11:55:27 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next] dibs: Avoid inconsistent lockstate warning in dibs_lo_move_data() To: sashiko-reviews@lists.linux.dev Cc: Alexander Gordeev , Heiko Carstens , linux-s390@vger.kernel.org, Vasily Gorbik , Christian Borntraeger References: <20260904094446.1342654-1-wintera@linux.ibm.com> <20260905094515.D65911F00A3D@smtp.kernel.org> Content-Language: en-US From: Alexandra Winter In-Reply-To: <20260905094515.D65911F00A3D@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=E7T9Y6dl c=1 sm=1 tr=0 ts=6a9fdb94 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=2redr1V9L8-sxEALg8QA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA4MDEwMCBTYWx0ZWRfX57JHqg8KiJkB wsY0ZbumEaKLudN8V2/gWIMkWHG81fINvHqTcmNvT1YXBG1mWzMiqYZoyN5Ps6C19rf4WUzDY4X 22WVCDeMmBT23aLDaIc9kd4PhjPihOk= X-Proofpoint-ORIG-GUID: NhOc5yEyrGyUcU_j9nSM_6d52_3XYdA1 X-Proofpoint-GUID: NhOc5yEyrGyUcU_j9nSM_6d52_3XYdA1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA4MDEwMCBTYWx0ZWRfX403J6N2YHWTz puhEAwJ3RKAYvcsKTH7BmSnrausFzYDvYkF65N5P14oVsd54Y0PVgF7xUW5kS4KBA6zO6297uYQ kjFoYLWCzdptpekeqdJo7gDjLe/4Cx/FJYvweRAopLWB8D6TQSpCvHZGvNkPBRV+ZnlcHYuaeEe L0CQZd8j+Yvw0fBs77sZ1vhXTHAxZA3KbJrvISj5cr08kZN4ZsZb6TEUcUud/Xsq5D55FLW8m4X 5JvCwzn37Idz3osvnFR7iH6/NpXX1+/cHCQLxP6mwAhtQXQFH5+AAq+uCEz4lvNpQokjUmBWlx2 5p4PmQYDbiiHh7IpJFW6RZRjwOfjSiRRjnJVE/nhqufsN2Qr4jbfFTpCKUrKP5giDOWWAH36fF6 QR5ctVeeoaZPRwr/Owq3CBWTzF4qLoZccD0MOWA3eFD8Al38CmmsGAI+2b0RQLdTPYRFiqyQYsb pEFsX9OAMo+Nxw7418A== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-08_01,2026-09-07_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 phishscore=0 spamscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609080100 On 05.09.26 11:45, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > > Pre-existing issues: > - [High] Unsafe error path calling kfree() on memory allocated via folio_alloc(). > -- > > commit 71f881ca9b5f87a2235598ada197106f8482dccb > Author: Alexandra Winter > > dibs: Avoid inconsistent lockstate warning in dibs_lo_move_data() > > dibs->lock is acquired in process context and interrupt context > (ism_handle_irq()). So always use spin_lock_irqsave() in process context. > > Note that this is not a real deadlock, as dibs_lo devices don't have > any interrupt context. > > [ ... ] > >> diff --git a/drivers/dibs/dibs_loopback.c b/drivers/dibs/dibs_loopback.c >> index 649e4e375be33..44a2e74c2efcb 100644 >> --- a/drivers/dibs/dibs_loopback.c >> +++ b/drivers/dibs/dibs_loopback.c > > [ ... ] > > While reviewing this commit, I noticed a pre-existing issue in the related > ism_alloc_dmb() function: > > drivers/s390/net/ism_drv.c:ism_alloc_dmb() { > [ ... ] > folio = folio_alloc(GFP_KERNEL | __GFP_NOWARN | __GFP_NOMEMALLOC | > __GFP_NORETRY, get_order(dmb->dmb_len)); > > if (!folio) { > rc = -ENOMEM; > goto out_bit; > } > > dmb->cpu_addr = folio_address(folio); > dmb->dma_addr = dma_map_page(&ism->pdev->dev, > virt_to_page(dmb->cpu_addr), 0, > dmb->dmb_len, DMA_FROM_DEVICE); > if (dma_mapping_error(&ism->pdev->dev, dmb->dma_addr)) { > rc = -ENOMEM; > goto out_free; > } > > return 0; > > out_free: > kfree(dmb->cpu_addr); > [ ... ] > } > > [Severity: High] > This is a pre-existing issue, but does calling kfree() on memory directly > allocated by folio_alloc() cause a kernel panic due to invalid slab metadata? > > When dma_map_page() fails, the execution jumps to the out_free label, which > incorrectly calls kfree(dmb->cpu_addr) instead of using folio_put() as seen > in ism_free_dmb(). > > If a user exhausts DMA mapping space (e.g., filling up the IOMMU or exhausting > bounce buffers), could this error path be triggered resulting in a denial of > service? > Fix for this is is already in netdev: https://git.kernel.org/netdev/net/c/907a56ab3eb8