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([2402:e280:3d17:646:b60a:307f:3199:d66f]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82379b65068sm19821711b3a.27.2026.02.02.21.02.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Feb 2026 21:02:09 -0800 (PST) Message-ID: <399d4ea0-5f70-4678-b0d6-9a80c3399ceb@gmail.com> Date: Tue, 3 Feb 2026 10:32:06 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH] wifi: ath12k: fix CMA error and MHI state mismatch during resume To: Baochen Qiang , jjohnson@kernel.org, kvalo@kernel.org Cc: quic_bqiang@quicinc.com, linux-wireless@vger.kernel.org, ath12k@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260202151720.49904-1-bjsaikiran@gmail.com> <125f0ecb-79a5-4806-aa93-aecaf937885e@oss.qualcomm.com> Content-Language: en-US From: Jayasaikiran Banigallapati In-Reply-To: <125f0ecb-79a5-4806-aa93-aecaf937885e@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2/3/26 08:21, Baochen Qiang wrote: > > On 2/2/2026 11:17 PM, Saikiran wrote: >> Commit 8d5f4da8d70b ("wifi: ath12k: support suspend/resume") introduced >> system suspend/resume support but caused a critical regression where >> CMA pages are corrupted during resume. >> >> 1. CMA page corruption: >> Calling mhi_unprepare_after_power_down() during suspend (via >> ATH12K_MHI_DEINIT) prematurely frees the fbc_image and rddm_image >> DMA buffers. When these pages are accessed during resume, the kernel >> detects corruption (Bad page state). > How, FBC image and RDDM image get re-allocated at resume, no? > > To clarify, the BUG: Bad page state crash actually occurs during the > suspend phase, specifically when ath12k_mhi_stop() calls > mhi_unprepare_after_power_down(). > > The stack trace shows the panic happens inside mhi_free_bhie_table() > while trying to free the pages: > >  mhi_free_bhie_table+0x50/0xa0 [mhi] >  mhi_unprepare_after_power_down+0x30/0x70 [mhi] >  ath12k_mhi_stop+0xf8/0x210 [ath12k] >  ath12k_core_suspend_late+0x94/0xc0 [ath12k] > > The kernel reports nonzero _refcount when attempting to free the CMA > pages (fbc_image/rddm_image). This suggests that something is still > holding a reference to these pages when DEINIT attempts to free them, > causing the kernel to panic before we reach the resume stage. > > Since the pages cannot be safely freed during suspend, skipping DEINIT > (and using MHI_POWER_OFF_KEEP_DEV) avoids this invalid free operation. > This also aligns with the existing comment in ath12k_mhi_stop which > suggests using mhi_power_down_keep_dev() for suspend. > > Thanks & Regards, > Saikiran