From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 803DF223335; Mon, 28 Jul 2025 08:40:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753692041; cv=none; b=e9X8nETYavIsTTC8DNsRZ21V3mFP13TnToYuE+Exk3X/s8J1uMlYSGXL1JMFzttQNw+HCz3BI83kno0DLdixk1uHy9i5sXCC4kVriuFf6W6oxJem/ErtGhZwQNcFcZgbvT1ezoyABRMVX1uuC2HdA29MY4zlGFwkfJyNU6OJNrY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753692041; c=relaxed/simple; bh=rwZJrVP1BT5tyiRZqif+sOLydn/x61D0kRyFWOASAlI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Wjs4tmGjH5jFJp+QjXG2pDiq8B/s58BVnegywVh+2hSaIwZo07xQjK5ZkPz94FZ0VZjd+O0AGHFfkY2bdQFaI9uj6wQgcB5ll1XzHJ/GQj/mI/RACcOpTCPSTtES1LH2dqNFdVN9Qzkw4/YKMEVVg4/3xtVKXhtgmSK6T/BaxTs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=sWQVgqrq; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="sWQVgqrq" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1753692029; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=uwm9cj3KRx8yDX4BDFgC32VZtWRWP0lSPfYpNdFr2MU=; b=sWQVgqrqtMCygYbG/+CY8/b+0EwUQggYs/Nmj1ljBI8p274lFKpKlGXxlLXkD0rubm5vChrbAjswX6dSx/DLb5vkeMojNM6iyyY5ZgD2/cBsIxBcFhpuUcRXwoz/jJWcO/S0OAkki9s+pDA2BLfbgeFBgyT9mycnRIpGfpwavhU= Received: from 30.246.181.19(mailfrom:xueshuai@linux.alibaba.com fp:SMTPD_---0WkG7MMX_1753692028 cluster:ay36) by smtp.aliyun-inc.com; Mon, 28 Jul 2025 16:40:29 +0800 Message-ID: <316cd6b2-3519-4353-8c53-06997096b216@linux.alibaba.com> Date: Mon, 28 Jul 2025 16:40:28 +0800 Precedence: bulk X-Mailing-List: dmaengine@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] dmaengine: idxd: Fix refcount underflow on module unload To: Yi Sun , Fenghua Yu Cc: vinicius.gomes@intel.com, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, dave.jiang@intel.com, gordon.jin@intel.com, xueshuai@linux.alibaba.com References: <20250617102712.727333-1-yi.sun@intel.com> <20250617102712.727333-3-yi.sun@intel.com> <39398407-009e-4afe-acb6-e3de931627d7@nvidia.com> From: Shuai Xue In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, Yi Sun, Fenghua Yu, 在 2025/7/27 17:16, Yi Sun 写道: > On 17.06.2025 14:58, Fenghua Yu wrote: >> Hi, Yi, >> >> On 6/17/25 03:27, Yi Sun wrote: >>> A recent refactor introduced a misplaced put_device() call, leading to a >>> reference count underflow during module unload. >>> >>> There is no need to add additional put_device() calls for idxd groups, >>> engines, or workqueues. Although commit a409e919ca3 claims:"Note, this >>> also fixes the missing put_device() for idxd groups, engines, and wqs." >>> It appears no such omission existed. The required cleanup is already >>> handled by the call chain: >>> >>> >>> Extend idxd_cleanup() to perform the necessary cleanup, and remove >>> idxd_cleanup_internals() which was not originally part of the driver >>> unload path and introduced unintended reference count underflow. >>> >>> Fixes: a409e919ca32 ("dmaengine: idxd: Refactor remove call with idxd_cleanup() helper") >>> Signed-off-by: Yi Sun >>> >>> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c >>> index 40cc9c070081..40f4bf446763 100644 >>> --- a/drivers/dma/idxd/init.c >>> +++ b/drivers/dma/idxd/init.c >>> @@ -1292,7 +1292,10 @@ static void idxd_remove(struct pci_dev *pdev) >>> device_unregister(idxd_confdev(idxd)); >>> idxd_shutdown(pdev); >>> idxd_device_remove_debugfs(idxd); >>> - idxd_cleanup(idxd); >>> + perfmon_pmu_remove(idxd); >>> + idxd_cleanup_interrupts(idxd); >>> + if (device_pasid_enabled(idxd)) >>> + idxd_disable_system_pasid(idxd); >>> >> This will hit memory leak issue. >> >> idxd_remove_internals() does not only put_device() but also free allocated memory for wqs, engines, groups. Without calling idxd_remove_internals(), the allocated memory is leaked. >> >> I think a right fix is to remove the put_device() in idxd_cleanup_wqs/engines/groups() because: >> >> 1. idxd_setup_wqs/engines/groups() does not call get_device(). Their counterpart idxd_cleanup_wqs/engines/groups() shouldn't call put_device(). >> >> 2. Fix the issue mentioned in this patch while there is no memory leak issue. >> >>> pci_iounmap(pdev, idxd->reg_base); >>> put_device(idxd_confdev(idxd)); >>> pci_disable_device(pdev); >> >> Thanks. >> >> -Fenghua >> > > Hi Fenghua, > > As with the comments on the previous patch, the function > idxd_conf_device_release already covers part of what is done in > idxd_remove_internals, including: > kfree(idxd->groups); > kfree(idxd->wqs); > kfree(idxd->engines); > kfree(idxd); > > We need to redesign idxd_remove_internals to clearly identify what > truely result in memory leaks and should be handled there. > Then, we'll need another patch to fix the idxd_remove_internals and call > it here. > > Let's prioritize addressing the two critical issues we've encountered here, > and then revisit the memory leak discussion afterward. > > Thanks > --Sun, Yi The root cause is simliar to Patch 1, the idxd_conf_device_release() function already handles part of the cleanup that idxd_cleanup_internals() attempts to do, e.g. idxd->wqs idxd->einges idxd->groups As a result, it causes user-after-free issue. ------------[ cut here ]------------ WARNING: CPU: 190 PID: 13854 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110 refcount_t: underflow; use-after-free. drm_client_lib(E) i2c_algo_bit(E) drm_shmem_helper(E) drm_kms_helper(E) nvme(E) mlx5_core(E) mlxfw(E) nvme_core(E) pci_hyperv_intf(E) psample(E) drm(E) wmi(E) pinctrl_emmitsburg(E) sd_mod(E) sg(E) ahci(E) libahci(E) libata(E) fuse(E) Modules linked in: binfmt_misc(E) bonding(E) tls(E) intel_rapl_msr(E) intel_rapl_common(E) intel_uncore_frequency(E) intel_uncore_frequency_common(E) i10nm_edac(E) skx_edac_common(E) nfit(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) coretemp(E) kvm_intel(E) snd_hda_intel(E) kvm(E) snd_intel_dspcfg(E) snd_hda_codec(E) mlx5_ib(E) irqbypass(E) qat_4xxx(E) snd_hda_core(E) dax_hmem(E) ghash_clmulni_intel(E) intel_qat(E) cxl_acpi(E) snd_hwdep(E) rapl(E) snd_pcm(E) cxl_port(E) iTCO_wdt(E) intel_cstate(E) iTCO_vendor_support(E) snd_timer(E) ib_uverbs(E) pmt_telemetry(E) cxl_core(E) rfkill(E) tun(E) dh_generic(E) pmt_class(E) intel_uncore(E) einj(E) pcspkr(E) isst_if_mbox_pci(E) joydev(E) isst_if_mmio(E) idxd(E-) crc8(E) ib_core(E) isst_if_common(E) authenc(E) intel_vsec(E) idxd_bus(E) snd(E) i2c_i801(E) mei_me(E) soundcore(E) i2c_smbus(E) i2c_ismt(E) mei(E) nf_tables(E) nfnetlink(E) ipmi_ssif(E) acpi_power_meter(E) ipmi_si(E) acpi_ipmi(E) ipmi_devintf(E) ipmi_msghandle CPU: 190 UID: 0 PID: 13854 Comm: rmmod Kdump: loaded Tainted: G S E 6.16.0-rc6+ #116 PREEMPT(none) Tainted: [S]=CPU_OUT_OF_SPEC, [E]=UNSIGNED_MODULE Hardware name: Inspur AliServer-Xuanwu2.0-02-1UCG42PF/AS2111TG5, BIOS 3.0.ES.AL.P.090.01 02/22/2024 RIP: 0010:refcount_warn_saturate+0xbe/0x110 RSP: 0018:ff7078d2df957db8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RBP: ff2b10355b055000 R08: 0000000000000000 R09: ff7078d2df957c68 RDX: ff2b10b33fdaa3c0 RSI: 0000000000000001 RDI: ff2b10b33fd9c440 R10: ff7078d2df957c60 R11: ffffffffbe761d68 R12: ff2b1035a00db400 R13: ff2b10355670b148 R14: ff2b103555097c80 R15: ffffffffc0a88938 FS: 00007fb5f8f3b740(0000) GS:ff2b10b380bb9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005560a898c2d8 CR3: 00000080f9def005 CR4: 0000000000f73ef0 PKRU: 55555554 Code: 01 01 e8 35 9b 9a ff 0f 0b c3 cc cc cc cc 80 3d 05 4c f5 01 00 75 85 48 c7 c7 30 21 75 bd c6 05 f5 4b f5 01 01 e8 12 9b 9a ff <0f> 0b c3 cc cc cc cc 80 3d e0 4b f5 01 00 0f 85 5e ff ff ff 48 c7 Call Trace: idxd_cleanup+0x6b/0x100 [idxd] idxd_remove+0x46/0x70 [idxd] pci_device_remove+0x3f/0xb0 driver_detach+0x48/0x90 device_release_driver_internal+0x197/0x200 bus_remove_driver+0x6d/0xf0 idxd_exit_module+0x34/0x6c0 [idxd] __do_sys_delete_module.constprop.0+0x174/0x310 do_syscall_64+0x5f/0x2d0 pci_unregister_driver+0x2e/0xb0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7fb5f8a620cb Code: 73 01 c3 48 8b 0d a5 6d 19 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 6d 19 00 f7 d8 64 89 01 48 RSP: 002b:00007ffeed6101c8 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 RAX: ffffffffffffffda RBX: 00005560a8981790 RCX: 00007fb5f8a620cb RDX: 000000000000000a RSI: 0000000000000800 RDI: 00005560a89817f8 R13: 00007ffeed612352 R14: 00005560a89812a0 R15: 00005560a8981790 R10: 00007fb5f8baaac0 R11: 0000000000000206 R12: 00007ffeed6103f0 ---[ end trace 0000000000000000 ]--- With this patch applied, the user-after-free issue is fixed. But, there is still memory leaks in idxd->wqs[i] idxd->einges[i] idxd->groups[i] I agree with Vinicius that we should cleanup in idxd_conf_device_release(). Thanks. Shuai