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[115.65.196.228]) by smtp.gmail.com with ESMTPSA id c1sm17999211pfo.197.2020.06.16.12.19.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Jun 2020 12:19:45 -0700 (PDT) Date: Wed, 17 Jun 2020 04:19:43 +0900 From: Stafford Horne To: Michel Lespinasse Cc: Palmer Dabbelt , atishp@atishpatra.org, linux-riscv@lists.infradead.org, LKML , Bjorn Topel Subject: Re: mm lock issue while booting Linux on 5.8-rc1 for RISC-V Message-ID: <20200616191943.GA1401039@lianli.shorne-pla.net> References: <20200616045108.GP75760@lianli.shorne-pla.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 16, 2020 at 03:44:49AM -0700, Michel Lespinasse wrote: > I am also unable to reproduce the issue so far. > > I wanted to point to a few things in case this helps: > - Commit 42fc541404f2 was bisected as the cause. This commit changes > walk_page_range_novma() to use mmap_assert_locked() instead of > lockdep_assert_held() > - mmap_assert_locked() checks lockdep_assert_held(), but also checks > that the rwsem itself is locked. > > Now how could lockdep think the lock is held, but the lock itself is > not marked as locked ??? > > I'm not sure if it helps at all, but a few commits earlier, > 0cc55a0213a0 introduces mmap_read_trylock_non_owner(), which is used > exclusively by stackmap, and does the opposite: it acquires the mmap > lock without telling lockdep about it. I can't see any smoking gun > linking this to our bug, but I thought it may be worth mentioning as > it involves the same suspects (stackmap and the difference between > owning the lock vs lockdep thinking we own the lock). > > I'm sorry, that's only how far I was able to go on this bug - I'm not > sure how to investigate it further as I can not reproduce the issue... Hello Michel, Thanks for your notes, it may be related. On my OpenRISC build with DEBUG_LOCKDEP and DEBUG_VM I am seeing the below trace. Without DEBUG_VM enabled the system does seem to work normally. Some notes on the trace: - The mmap_assert_locked failure is not in the same place as RISC-V, but similarly during walk_page_range not walk_page_range_novma. - This build does not use BPF. - I do see a LOCKDEP warning early on, which may be the cause. I will still do some more investination, you input is very helpful. -Stafford exec: /home/shorne/work/openrisc/qemu/build/or1k-softmmu/qemu-system-or1k -cpu or1200 -M or1k-sim -kernel /home/shorne/work/linux/vmlinux -net nic -net tap,ifname=tap0,script=no,downscript=no -serial mon:stdio -nographic -gdb tcp::10001 -m 512 [ 0.000000] Compiled-in FDT at (ptrval) [ 0.000000] Linux version 5.8.0-rc1-simple-smp-00002-g2335724b6a99-dirty (shorne@lianli.shorne-pla.net) (or1k-elf-gcc (GCC) 9.0.1 20190409 (experimental), GNU ld (GNU Binutils) 2.32.51.20190425) #140 Wed Jun 17 04:01:43 JST 2020 [ 0.000000] CPU: OpenRISC-13 (revision 8) @20 MHz [ 0.000000] -- dcache disabled [ 0.000000] -- icache disabled [ 0.000000] -- dmmu: 128 entries, 1 way(s) [ 0.000000] -- immu: 128 entries, 1 way(s) [ 0.000000] -- additional features: [ 0.000000] -- power management [ 0.000000] -- PIC [ 0.000000] -- timer [ 0.000000] setup_memory: Memory: 0x0-0x2000000 [ 0.000000] Setting up paging and PTEs. [ 0.000000] map_ram: Memory: 0x0-0x2000000 [ 0.000000] Zone ranges: [ 0.000000] Normal [mem 0x0000000000000000-0x0000000001ffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000000000000-0x0000000001ffffff] [ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000001ffffff] [ 0.000000] On node 0 totalpages: 4096 [ 0.000000] Normal zone: 16 pages used for memmap [ 0.000000] Normal zone: 0 pages reserved [ 0.000000] Normal zone: 4096 pages, LIFO batch:0 [ 0.000000] itlb_miss_handler (ptrval) [ 0.000000] dtlb_miss_handler (ptrval) [ 0.000000] OpenRISC Linux -- http://openrisc.io [ 0.000000] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768 [ 0.000000] pcpu-alloc: [0] 0 [ 0.000000] Built 1 zonelists, mobility grouping off. Total pages: 4080 [ 0.000000] ------------[ cut here ]------------ [ 0.000000] WARNING: CPU: 0 PID: 0 at kernel/locking/mutex.c:1242 __mutex_unlock_slowpath+0x328/0x3ec [ 0.000000] DEBUG_LOCKS_WARN_ON(__owner_task(owner) != current) [ 0.000000] Modules linked in: [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.8.0-rc1-simple-smp-00002-g2335724b6a99-dirty #140 [ 0.000000] Call trace: [ 0.000000] [<(ptrval)>] dump_stack+0x34/0x48 [ 0.000000] [<(ptrval)>] __warn+0x104/0x158 [ 0.000000] [<(ptrval)>] ? __mutex_unlock_slowpath+0x328/0x3ec [ 0.000000] [<(ptrval)>] warn_slowpath_fmt+0x7c/0x94 [ 0.000000] [<(ptrval)>] __mutex_unlock_slowpath+0x328/0x3ec [ 0.000000] [<(ptrval)>] ? vprintk_emit+0x1e8/0x3d8 [ 0.000000] [<(ptrval)>] ? page_alloc_cpu_dead+0x0/0x30 [ 0.000000] [<(ptrval)>] mutex_unlock+0x18/0x28 [ 0.000000] [<(ptrval)>] __cpuhp_setup_state_cpuslocked+0x200/0x2f4 [ 0.000000] [<(ptrval)>] ? vprintk_func+0x94/0x14c [ 0.000000] [<(ptrval)>] ? start_kernel+0x0/0x684 [ 0.000000] [<(ptrval)>] __cpuhp_setup_state+0x14/0x24 [ 0.000000] [<(ptrval)>] page_alloc_init+0x34/0x68 [ 0.000000] [<(ptrval)>] ? start_kernel+0x1a0/0x684 [ 0.000000] [<(ptrval)>] ? early_init_dt_scan_nodes+0x60/0x70 [ 0.000000] irq event stamp: 0 [ 0.000000] hardirqs last enabled at (0): [<00000000>] 0x0 [ 0.000000] hardirqs last disabled at (0): [<00000000>] 0x0 [ 0.000000] softirqs last enabled at (0): [<00000000>] 0x0 [ 0.000000] softirqs last disabled at (0): [<00000000>] 0x0 [ 0.000000] random: get_random_bytes called from print_oops_end_marker+0x40/0x98 with crng_init=0 [ 0.000000] ---[ end trace 0000000000000000 ]--- [ 0.000000] Kernel command line: earlycon [ 0.000000] earlycon: ns16550a0 at MMIO 0x90000000 (options '115200') [ 0.000000] printk: bootconsole [ns16550a0] enabled [ 0.000000] Dentry cache hash table entries: 4096 (order: 1, 16384 bytes, linear) [ 0.000000] Inode-cache hash table entries: 2048 (order: 0, 8192 bytes, linear) [ 0.000000] Sorting __ex_table... [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off [ 0.000000] Memory: 11384K/32768K available (4756K kernel code, 380K rwdata, 1160K rodata, 4072K init, 10784K bss, 21384K reserved, 0K cma-reserved) [ 0.000000] mem_init_done ........................................... [ 0.000000] Running RCU self tests [ 0.000000] NR_IRQS: 32, nr_irqs: 32, preallocated irqs: 0 [ 0.000000] clocksource: openrisc_timer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 95563022313 ns [ 0.000000] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar [ 0.000000] ... MAX_LOCKDEP_SUBCLASSES: 8 [ 0.000000] ... MAX_LOCK_DEPTH: 48 [ 0.000000] ... MAX_LOCKDEP_KEYS: 8192 [ 0.000000] ... CLASSHASH_SIZE: 4096 [ 0.000000] ... MAX_LOCKDEP_ENTRIES: 32768 [ 0.000000] ... MAX_LOCKDEP_CHAINS: 65536 [ 0.000000] ... CHAINHASH_SIZE: 32768 [ 0.000000] memory used by lock dependency info: 3773 kB [ 0.000000] memory used for stack traces: 2112 kB [ 0.000000] per task-struct memory footprint: 1344 bytes [ 0.010000] 40.00 BogoMIPS (lpj=200000) [ 0.010000] pid_max: default: 32768 minimum: 301 [ 0.010000] Mount-cache hash table entries: 2048 (order: 0, 8192 bytes, linear) [ 0.010000] Mountpoint-cache hash table entries: 2048 (order: 0, 8192 bytes, linear) [ 0.150000] devtmpfs: initialized [ 0.210000] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns [ 0.210000] futex hash table entries: 256 (order: 0, 12288 bytes, linear) [ 0.240000] NET: Registered protocol family 16 [ 0.450000] clocksource: Switched to clocksource openrisc_timer [ 2.820000] NET: Registered protocol family 2 [ 2.840000] tcp_listen_portaddr_hash hash table entries: 256 (order: 0, 11264 bytes, linear) [ 2.850000] TCP established hash table entries: 2048 (order: 0, 8192 bytes, linear) [ 2.850000] TCP bind hash table entries: 2048 (order: 3, 81920 bytes, linear) [ 2.850000] TCP: Hash tables configured (established 2048 bind 2048) [ 2.860000] UDP hash table entries: 256 (order: 1, 24576 bytes, linear) [ 2.860000] UDP-Lite hash table entries: 256 (order: 1, 24576 bytes, linear) [ 2.880000] NET: Registered protocol family 1 [ 2.900000] RPC: Registered named UNIX socket transport module. [ 2.900000] RPC: Registered udp transport module. [ 2.900000] RPC: Registered tcp transport module. [ 2.900000] RPC: Registered tcp NFSv4.1 backchannel transport module. [ 4.120000] workingset: timestamp_bits=30 max_order=11 bucket_order=0 [ 4.150000] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled [ 4.210000] printk: console [ttyS0] disabled [ 4.220000] 90000000.serial: ttyS0 at MMIO 0x90000000 (irq = 2, base_baud = 1250000) is a 16550A [ 4.230000] printk: console [ttyS0] enabled [ 4.230000] printk: console [ttyS0] enabled [ 4.230000] printk: bootconsole [ns16550a0] disabled [ 4.230000] printk: bootconsole [ns16550a0] disabled [ 4.280000] libphy: Fixed MDIO Bus: probed [ 4.310000] mm c05fb530 mmap 00000000 seqnum 0 task_size 0 [ 4.310000] get_unmapped_area 00000000 [ 4.310000] mmap_base 0 mmap_legacy_base 0 highest_vm_end 0 [ 4.310000] pgd c05d2000 mm_users 2 mm_count 2 pgtables_bytes 0 map_count 0 [ 4.310000] hiwater_rss 0 hiwater_vm 0 total_vm 0 locked_vm 0 [ 4.310000] pinned_vm 0 data_vm 0 exec_vm 0 stack_vm 0 [ 4.310000] start_code c0000000 end_code c04a5208 start_data 0 end_data c06263d8 [ 4.310000] start_brk 0 brk c14aa360 start_stack 0 [ 4.310000] arg_start 0 arg_end 0 env_start 0 env_end 0 [ 4.310000] binfmt 00000000 flags 0 core_state 00000000 [ 4.310000] exe_file 00000000 [ 4.310000] tlb_flush_pending 0 [ 4.310000] def_flags: 0x0() [ 4.310000] BUG: failure at include/linux/mmap_lock.h:81/mmap_assert_locked()! [ 4.310000] CPU: 0 PID: 1 Comm: swapper Tainted: G W 5.8.0-rc1-simple-smp-00002-g2335724b6a99-dirty #140 [ 4.310000] Call trace: [ 4.320000] [<(ptrval)>] dump_stack+0x34/0x48 [ 4.320000] [<(ptrval)>] walk_page_range+0x230/0x244 [ 4.320000] [<(ptrval)>] arch_dma_set_uncached+0x38/0x60 [ 4.320000] [<(ptrval)>] dma_direct_alloc_pages+0x104/0x178 [ 4.320000] [<(ptrval)>] dma_direct_alloc+0x14/0x24 [ 4.320000] [<(ptrval)>] dma_alloc_attrs+0x9c/0x13c [ 4.320000] [<(ptrval)>] dmam_alloc_attrs+0x80/0xf4 [ 4.320000] [<(ptrval)>] ethoc_probe+0x1b0/0x884 [ 4.320000] [<(ptrval)>] ? ignore_unknown_bootoption+0x0/0x24 [ 4.320000] [<(ptrval)>] platform_drv_probe+0x3c/0xa8 [ 4.320000] [<(ptrval)>] really_probe+0x238/0x42c [ 4.320000] [<(ptrval)>] ? __driver_attach+0x0/0x140 [ 4.320000] [<(ptrval)>] ? ignore_unknown_bootoption+0x0/0x24 [ 4.320000] [<(ptrval)>] driver_probe_device+0x50/0xa8 [ 4.320000] [<(ptrval)>] ? __device_driver_lock+0x44/0x84 [ 4.320000] [<(ptrval)>] device_driver_attach+0x88/0x90 [ 4.320000] [<(ptrval)>] __driver_attach+0x84/0x140 [ 4.320000] [<(ptrval)>] ? __driver_attach+0x0/0x140 [ 4.330000] [<(ptrval)>] bus_for_each_dev+0x8c/0xd4 [ 4.330000] [<(ptrval)>] driver_attach+0x28/0x38 [ 4.330000] [<(ptrval)>] bus_add_driver+0x1dc/0x270 [ 4.330000] [<(ptrval)>] ? ethoc_driver_init+0x0/0x30 [ 4.330000] [<(ptrval)>] ? ethoc_driver_init+0x0/0x30 [ 4.330000] [<(ptrval)>] driver_register+0xbc/0x1a8 [ 4.330000] [<(ptrval)>] ? phy_drivers_register+0x68/0xdc [ 4.330000] [<(ptrval)>] ? ethoc_driver_init+0x0/0x30 [ 4.330000] [<(ptrval)>] __platform_driver_register+0x50/0x60 [ 4.330000] [<(ptrval)>] ethoc_driver_init+0x20/0x30 [ 4.330000] [<(ptrval)>] do_one_initcall+0x80/0x2e0 [ 4.330000] [<(ptrval)>] ? parse_args+0x270/0x4f0 [ 4.330000] [<(ptrval)>] kernel_init_freeable+0x1c8/0x268 [ 4.330000] [<(ptrval)>] ? ignore_unknown_bootoption+0x0/0x24 [ 4.330000] [<(ptrval)>] ? kernel_init+0x0/0x144 [ 4.330000] [<(ptrval)>] kernel_init+0x18/0x144 [ 4.340000] [<(ptrval)>] ? schedule_tail+0x54/0x94 [ 4.340000] [<(ptrval)>] ret_from_fork+0x1c/0x150 [ 4.340000] Kernel panic - not syncing: BUG! [ 4.340000] ---[ end Kernel panic - not syncing: BUG! ]--- > On Tue, Jun 16, 2020 at 1:40 AM Palmer Dabbelt wrote: > > > > On Mon, 15 Jun 2020 21:51:08 PDT (-0700), shorne@gmail.com wrote: > > > On Tue, Jun 16, 2020 at 06:57:47AM +0900, Stafford Horne wrote: > > >> On Mon, Jun 15, 2020 at 12:28:11AM -0700, Atish Patra wrote: > > >> > Hi, > > >> > I encountered the following issue while booting 5.8-rc1 on Qemu for RV64. > > >> > I added additional dump_stack and observed that it's happening in bpf free path. > > >> > It happens always if CONFIG_DEBUG_VM is enabled. VM_BUG_ON_MM is > > >> > compiled away without that. > > >> > ------------------------------------------------------------------------ > > >> > forked to background, child pid 113 > > >> > [ 10.328850] CPU: 3 PID: 51 Comm: kworker/3:1 Not tainted > > >> > 5.8.0-rc1-dirty #732 > > >> > [ 10.331739] Workqueue: events bpf_prog_free_deferred > > >> > [ 10.334133] Call Trace: > > >> > [ 10.338039] [] walk_stackframe+0x0/0xa4 > > >> > [ 10.339988] [] show_stack+0x2e/0x3a > > >> > [ 10.340902] [] dump_stack+0x72/0x8c > > >> > [ 10.341451] [] mmap_assert_locked.part.13+0x14/0x1c > > >> > [ 10.342131] [] walk_page_range_novma+0x0/0x4e > > >> > [ 10.342973] [] set_direct_map_invalid_noflush+0x66/0x6e > > >> > [ 10.343917] [] __vunmap+0xe8/0x212 > > >> > [ 10.344680] [] __vfree+0x22/0x6e > > >> > [ 10.345270] [] vfree+0x34/0x56 > > >> > [ 10.345834] [] __bpf_prog_free+0x2c/0x36 > > >> > [ 10.346529] [] bpf_prog_free_deferred+0x74/0x8a > > >> > [ 10.347394] [] process_one_work+0x13a/0x272 > > >> > [ 10.348239] [] worker_thread+0x50/0x2e4 > > >> > [ 10.348900] [] kthread+0xfc/0x10a > > >> > [ 10.349470] [] ret_from_exception+0x0/0xc > > >> > [ 10.354405] mm ffffffe001018600 mmap 0000000000000000 seqnum 0 task_size 0 > > >> > [ 10.354405] get_unmapped_area 0000000000000000 > > >> > [ 10.354405] mmap_base 0 mmap_legacy_base 0 highest_vm_end 0 > > >> > [ 10.354405] pgd ffffffe001074000 mm_users 2 mm_count 1 > > >> > pgtables_bytes 8192 map_count 0 > > >> > [ 10.354405] hiwater_rss 0 hiwater_vm 0 total_vm 0 locked_vm 0 > > >> > [ 10.354405] pinned_vm 0 data_vm 0 exec_vm 0 stack_vm 0 > > >> > [ 10.354405] start_code ffffffe000200000 end_code ffffffe00084acc2 > > >> > start_data 0 end_data ffffffe00106dfe4 > > >> > [ 10.354405] start_brk 0 brk ffffffe0010bd6d0 start_stack 0 > > >> > [ 10.354405] arg_start 0 arg_end 0 env_start 0 env_end 0 > > >> > [ 10.354405] binfmt 0000000000000000 flags 0 core_state 0000000000000000 > > >> > [ 10.354405] ioctx_table 0000000000000000 > > >> > [ 10.354405] exe_file 0000000000000000 > > >> > [ 10.354405] tlb_flush_pending 0 > > >> > [ 10.354405] def_flags: 0x0() > > >> > [ 10.369325] ------------[ cut here ]------------ > > >> > [ 10.370763] kernel BUG at include/linux/mmap_lock.h:81! > > >> > [ 10.375235] Kernel BUG [#1] > > >> > [ 10.377198] Modules linked in: > > >> > [ 10.378931] CPU: 3 PID: 51 Comm: kworker/3:1 Not tainted 5.8.0-rc1-dirty #732 > > >> > [ 10.380179] Workqueue: events bpf_prog_free_deferred > > >> > [ 10.381270] epc: ffffffe0002db4d4 ra : ffffffe0002db4d4 sp : ffffffe3eaea7c70 > > >> > [ 10.382561] gp : ffffffe00106d950 tp : ffffffe3ef752f80 t0 : > > >> > ffffffe0010836e8 > > >> > [ 10.383996] t1 : 0000000000000064 t2 : 0000000000000000 s0 : > > >> > ffffffe3eaea7c90 > > >> > [ 10.385119] s1 : ffffffe001018600 a0 : 0000000000000289 a1 : > > >> > 0000000000000020 > > >> > [ 10.386099] a2 : 0000000000000005 a3 : 0000000000000000 a4 : > > >> > ffffffe001012758 > > >> > [ 10.387294] a5 : 0000000000000000 a6 : 0000000000000102 a7 : > > >> > 0000000000000006 > > >> > [ 10.388265] s2 : ffffffe3f00674c0 s3 : ffffffe00106e108 s4 : > > >> > ffffffe00106e100 > > >> > [ 10.389250] s5 : ffffffe00106e908 s6 : 0000000000000000 s7 : > > >> > 6db6db6db6db6db7 > > >> > [ 10.390272] s8 : 0000000000000001 s9 : ffffffe00021a4f8 s10: > > >> > ffffffffffffffff > > >> > [ 10.391293] s11: ffffffe3f0066600 t3 : 000000000001a7a8 t4 : > > >> > 000000000001a7a8 > > >> > [ 10.392314] t5 : 0000000000000000 t6 : ffffffe00107b76b > > >> > [ 10.393096] status: 0000000000000120 badaddr: 0000000000000000 > > >> > cause: 0000000000000003 > > >> > [ 10.397755] ---[ end trace 861659596ac28841 ]--- > > >> > --------------------------------------------------------------------------------------------------- > > >> > > > >> > I haven't had the chance to bisect to figure out which commit caused > > >> > the issue. Just wanted > > >> > to check if it is a known issue already. > > >> > > >> Hi Atish, > > >> > > >> Note, I am getting the same (just now) when booting v5.8-rc1 on OpenRISC. If > > >> you have any updates please post back. I will try to look into this today or > > >> tomorrow. > > > > > > I have bisected this to, 42fc541404f249778e752ab39c8bc25fcb2dbe1e: > > > > > > mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked() > > > > > > This should have just changed the existing lockdep api's but something has > > > changed. I haven't had time to look at it yet. > > > > > > Ccing: Michel Lespinasse > > > > This isn't manifesting on boot for me, on either rc1 or that commit. I'm > > running a simple buildroot-based userspace, so I doubt anything is triggering > > BPF. I don't run the BPF selftests, as they're a bit of a pain (IIRC they > > don't cross compile and need LLVM) -- does anyone have a userspace I can use to > > trigger the bug? > > > > -- > Michel "Walken" Lespinasse > A program is never fully debugged until the last user dies.