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[94.245.46.49]) by smtp.gmail.com with ESMTPSA id o23sm5487909lfg.0.2020.06.15.08.26.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 Jun 2020 08:26:45 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 15 Jun 2020 17:26:43 +0200 To: Ingo Molnar Cc: LKML , Ingo Molnar , x86@kernel.org, lkp@lists.01.org Subject: Re: [mm/vmalloc] 0acd9a0ded: kernel_BUG_at_mm/vmalloc.c Message-ID: <20200615152643.GA24242@pc636> References: <20200613142028.GP12456@shao2-debian> <20200613160758.GA11426@pc636> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200613160758.GA11426@pc636> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Ingo. > > Greeting, > > > > FYI, we noticed the following commit (built with gcc-9): > > > > commit: 0acd9a0ded80c986ccc9588ba2703436769ead74 ("Revert "mm/vmalloc: modify struct vmap_area to reduce its size"") > > https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git WIP.fixes > > > > in testcase: trinity > > with following parameters: > > > > runtime: 300s > > > > test-description: Trinity is a linux system call fuzz tester. > > test-url: http://codemonkey.org.uk/projects/trinity/ > > > > > > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > > > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): > > > > > > +----------------------------------------------------------------------------+------+------------+ > > | | v5.7 | 0acd9a0ded | > > +----------------------------------------------------------------------------+------+------------+ > > | boot_successes | 214 | 142 | > > | boot_failures | 3 | 16 | > > | WARNING:at_kernel/rcu/tree_stall.h:#rcu_check_gp_start_stall | 1 | | > > | EIP:rcu_check_gp_start_stall | 1 | | > > | WARNING:at_net/sched/sch_generic.c:#dev_watchdog | 1 | 2 | > > | EIP:dev_watchdog | 1 | 2 | > > | Kernel_panic-not_syncing:VFS:Unable_to_mount_root_fs_on_unknown-block(#,#) | 1 | | > > | kernel_BUG_at_mm/vmalloc.c | 0 | 11 | > > | invalid_opcode:#[##] | 0 | 11 | > > | EIP:free_vm_area | 0 | 11 | > > | Kernel_panic-not_syncing:Fatal_exception | 0 | 11 | > > | INFO:rcu_sched_detected_stalls_on_CPUs/tasks | 0 | 2 | > > | EIP:smp_call_function_single | 0 | 2 | > > | INFO:rcu_sched_self-detected_stall_on_CPU | 0 | 1 | > > | EIP:bvec_iter_advance | 0 | 1 | > > | EIP:iov_iter_copy_from_user_atomic | 0 | 1 | > > +----------------------------------------------------------------------------+------+------------+ > > > > > > If you fix the issue, kindly add following tag > > Reported-by: kernel test robot > > > > > > [ 330.604224] kernel BUG at mm/vmalloc.c:3211! > > [ 330.605254] invalid opcode: 0000 [#1] SMP > > [ 330.606027] CPU: 1 PID: 18 Comm: kworker/1:0 Not tainted 5.7.0-00001-g0acd9a0ded80c #1 > > [ 330.607482] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 > > [ 330.623780] Workqueue: events pcpu_balance_workfn > > [ 330.624815] EIP: free_vm_area+0x33/0x77 > > [ 330.625601] Code: 49 56 b5 01 83 15 64 49 56 b5 00 89 e5 53 89 c3 8b 40 04 e8 de fe ff ff 39 c3 74 2c 83 05 68 49 56 b5 01 83 15 6c 49 56 b5 00 <0f> 0b 83 05 78 49 56 b5 01 83 15 7c 49 56 b5 00 83 05 80 49 56 b5 > > [ 330.629386] EAX: 00000000 EBX: ef7a8380 ECX: 00000003 EDX: f46fa0c0 > > [ 330.630660] ESI: 00000000 EDI: 00000001 EBP: f473bedc ESP: f473bed8 > > [ 330.631954] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246 > > [ 330.633317] CR0: 80050033 CR2: a763a9e4 CR3: 3bc55000 CR4: 000006d0 > > [ 330.634576] Call Trace: > > [ 330.635134] pcpu_free_vm_areas+0x2b/0x64 > > [ 330.635973] pcpu_balance_workfn+0x673/0x9ac > > [ 330.636846] process_one_work+0x4e0/0x8b0 > > [ 330.637662] worker_thread+0x370/0x589 > > [ 330.638448] kthread+0x1f9/0x20c > > [ 330.639153] ? create_worker+0x24d/0x24d > > [ 330.639958] ? kthread_create_worker+0x38/0x38 > > [ 330.640863] ret_from_fork+0x19/0x30 > > [ 330.641597] Modules linked in: > > [ 330.643261] ---[ end trace acbe7a17ad39ff71 ]--- > > > > > > To reproduce: > > I interpreted this BUG_ON() differently. I thought that below revert fixes the BUG_ON() reported by the test robot: commit: 0acd9a0ded80c986ccc9588ba2703436769ead74 ("Revert "mm/vmalloc: modify struct vmap_area to reduce its size"") so basically it is vice versa. Due to that revert the vmalloc code triggers the BUG_ON(). Are you planning to keep revert and mainline it or that is just for test purposes? Thank you! -- Vlad Rezki