From: Wu Fengguang Subject: Re: 3.2.0-rc5 NULL dereference BUG Date: Sun, 18 Dec 2011 14:30:54 +0800 Message-ID: <20111218063054.GA4979@localhost> References: <20111218055359.GA17182@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, LKML To: "linux-ext4@vger.kernel.org" Return-path: Content-Disposition: inline In-Reply-To: <20111218055359.GA17182@localhost> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, Dec 18, 2011 at 01:53:59PM +0800, Wu Fengguang wrote: > This is very reproducible. It occurs in two of my test cases, with > different panic messages. > > It also shows up in 3.2.0-rc3. Kernel config is attached. Oh well, it happens even in 3.1. Here is the dmesg: [ 210.758668] ------------[ cut here ]------------ [ 210.764665] WARNING: at /c/wfg/linux/kernel/lockdep.c:690 __lock_acquire+0x155/0x938() [ 210.774369] Hardware name: SandyBridge Platform [ 210.779898] Modules linked in: [ 210.783852] Pid: 4409, comm: dd Not tainted 3.1.0+ #299 [ 210.790158] Call Trace: [ 210.793359] [] warn_slowpath_common+0x85/0x9d [ 210.800538] [] warn_slowpath_null+0x1a/0x1c [ 210.807523] [] __lock_acquire+0x155/0x938 [ 210.814312] [] lock_acquire+0xdd/0x10a [ 210.820815] [] ? double_rq_lock+0x45/0x57 [ 210.827607] [] _raw_spin_lock+0x36/0x69 [ 210.834145] [] ? double_rq_lock+0x45/0x57 [ 210.840927] [] double_rq_lock+0x45/0x57 [ 210.847528] [] load_balance+0x1f1/0x69b [ 210.854085] [] ? __lock_acquire+0x567/0x938 [ 210.861076] [] ? lock_release_holdtime+0xa3/0xac [ 210.868548] [] __schedule+0x39a/0x937 [ 210.874952] [] ? __schedule+0x313/0x937 [ 210.881556] [] ? __lock_acquire+0x567/0x938 [ 210.888548] [] ? native_sched_clock+0x2d/0x5f [ 210.895733] [] ? schedule_timeout+0x242/0x274 [ 210.902904] [] ? local_clock+0x41/0x5a [ 210.909395] [] ? lock_release_holdtime+0xa3/0xac [ 210.916814] [] ? schedule_timeout+0x242/0x274 [ 210.923995] [] schedule+0x5a/0x5c [ 210.929943] [] schedule_timeout+0x247/0x274 [ 210.936933] [] ? del_timer+0xc8/0xc8 [ 210.943246] [] io_schedule_timeout+0x98/0xe9 [ 210.950271] [] balance_dirty_pages_ratelimited_nr+0x4d2/0x686 [ 210.959399] [] generic_file_buffered_write+0x1c9/0x22d [ 210.967400] [] ? current_fs_time+0x27/0x2e [ 210.974295] [] __generic_file_aio_write+0x32e/0x35e [ 210.981993] [] generic_file_aio_write+0x66/0xc1 [ 210.989370] [] ext4_file_write+0x1f6/0x24f [ 210.996212] [] ? native_sched_clock+0x2d/0x5f [ 211.003399] [] ? fsnotify+0x216/0x26f [ 211.009805] [] ? local_clock+0x41/0x5a [ 211.016310] [] do_sync_write+0xcb/0x108 [ 211.022918] [] vfs_write+0xb8/0x157 [ 211.029125] [] sys_write+0x4d/0x77 [ 211.035228] [] system_call_fastpath+0x16/0x1b [ 211.042370] ---[ end trace a682372b42c1df33 ]--- [ 443.558240] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 [ 443.567910] IP: [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 443.577206] PGD 80e790067 PUD 8133be067 PMD 0 [ 443.582895] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC [ 443.588602] CPU 11 [ 443.590821] Modules linked in: [ 443.595323] [ 443.597439] Pid: 4252, comm: flush-8:16 Tainted: G W 3.1.0+ #299 Intel Corporation SandyBridge Platform/To be filled by O.E.M. [ 443.612154] RIP: 0010:[] [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 443.624266] RSP: 0018:ffff88041eb695d0 EFLAGS: 00010282 [ 443.630679] RAX: ffffe8fffc407380 RBX: ffff880815c061f8 RCX: ffff88041d9e4500 [ 443.639117] RDX: 0000000000000000 RSI: 0000000000000282 RDI: ffffe8fffc407380 [ 443.647564] RBP: ffff88041eb696b0 R08: ffff88041eb695f0 R09: 0000000000000000 [ 443.656006] R10: ffffe8fffc006ea0 R11: ffffffff8120745f R12: ffffffff81f07698 [ 443.664382] R13: ffff88041eb69760 R14: ffff88081f709750 R15: ffff88080a1a29d8 [ 443.672828] FS: 0000000000000000(0000) GS:ffff88082b400000(0000) knlGS:0000000000000000 [ 443.682722] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 443.689600] CR2: 0000000000000028 CR3: 00000008133bf000 CR4: 00000000000406e0 [ 443.697984] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 443.706430] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 443.714820] Process flush-8:16 (pid: 4252, threadinfo ffff88041eb68000, task ffff88041d9e45e0) [ 443.725298] Stack: [ 443.728009] 0000000000000000 0000000000000004 ffff88041eb69660 ffff88041eb695f0 [ 443.737474] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 443.746928] ffff88041eb69700 0000000000000000 0000000000000000 0000000000000000 [ 443.756380] Call Trace: [ 443.759585] [] ? ext4_mb_release_group_pa+0x40/0xfe [ 443.767347] [] ext4_mb_release_group_pa+0x40/0xfe [ 443.774916] [] ext4_mb_discard_group_preallocations+0x355/0x3eb [ 443.784233] [] ext4_mb_new_blocks+0x2de/0x3f4 [ 443.791414] [] ext4_ext_map_blocks+0xf63/0x1331 [ 443.798796] [] ? ext4_map_blocks+0xf5/0x1fa [ 443.805782] [] ext4_map_blocks+0x126/0x1fa [ 443.812671] [] mpage_da_map_and_submit+0xec/0x3b2 [ 443.820241] [] ext4_da_writepages+0x316/0x4b0 [ 443.827429] [] ? lock_release_non_nested+0x22c/0x293 [ 443.835299] [] do_writepages+0x24/0x2d [ 443.851241] [] writeback_single_inode+0x135/0x2c3 [ 443.858809] [] writeback_sb_inodes+0x182/0x22c [ 443.866078] [] __writeback_inodes_wb+0x78/0xb9 [ 443.873355] [] wb_writeback+0x16d/0x276 [ 443.879951] [] wb_do_writeback+0x1c8/0x1e3 [ 443.886831] [] ? del_timer+0xc8/0xc8 [ 443.893136] [] bdi_writeback_thread+0x8c/0x215 [ 443.900413] [] ? wb_do_writeback+0x1e3/0x1e3 [ 443.907490] [] kthread+0x8e/0x96 [ 443.913355] [] kernel_thread_helper+0x4/0x10 [ 443.920403] [] ? retint_restore_args+0x13/0x13 [ 443.927626] [] ? __init_kthread_worker+0x5b/0x5b [ 443.935099] [] ? gs_change+0x13/0x13 [ 443.941388] Code: 89 c2 4c 89 85 38 ff ff ff 48 8d 4d ec 41 0f b7 74 24 48 e8 3a d6 7a 00 4c 8b 85 38 ff ff ff 48 85 c0 74 50 48 8b 93 a0 00 00 00 [ 443.960015] 8b 52 28 8b 52 10 89 50 0c 48 8b 93 80 00 00 00 48 89 50 10 [ 443.970522] RIP [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 443.980029] RSP [ 443.984374] CR2: 0000000000000028 [ 443.988542] BUG: unable to handle kernel [ 443.988745] ---[ end trace a682372b42c1df34 ]--- [ 443.999169] NULL pointer dereference at 0000000000000028 [ 444.005637] IP: [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 444.014987] PGD 810faa067 PUD 8110f6067 PMD 0 [ 444.020575] Oops: 0000 [#2] SMP DEBUG_PAGEALLOC [ 444.026317] CPU 1 [ 444.028441] Modules linked in: [ 444.032997] [ 444.035107] Pid: 5480, comm: dd Tainted: G D W 3.1.0+ #299 Intel Corporation SandyBridge Platform/To be filled by O.E.M. [ 444.049013] RIP: 0010:[] [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 444.061108] RSP: 0018:ffff880809f252e8 EFLAGS: 00010282 [ 444.067494] RAX: ffffe8fbfd007380 RBX: ffff880811f6f458 RCX: ffff880809862200 [ 444.075922] RDX: 0000000000000000 RSI: 0000000000000282 RDI: ffffe8fbfd007380 [ 444.084349] RBP: ffff880809f253c8 R08: ffff880809f25308 R09: 0000000000000000 [ 444.092776] R10: ffffe8fffd206ea0 R11: ffffffff8120745f R12: ffffffff81f07698 [ 444.101194] R13: ffff880809f25478 R14: ffff88081f709750 R15: ffff880811f42930 [ 444.109607] FS: 00007f2265a23700(0000) GS:ffff88042c000000(0000) knlGS:0000000000000000 [ 444.119477] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 444.126350] CR2: 0000000000000028 CR3: 00000008110d3000 CR4: 00000000000406e0 [ 444.134777] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 444.143205] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 444.151633] Process dd (pid: 5480, threadinfo ffff880809f24000, task ffff8808098622f0) [ 444.161311] Stack: [ 444.164001] ffff880809f25358 0000000000000000 ffff88081d13a650 ffff880809f25308 [ 444.173422] 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 444.178355] ffff880809f25418 0000000000000000 0000000000000000 0000000000000000 [ 444.178358] Call Trace: [ 444.178364] [] ? ext4_mb_release_group_pa+0x40/0xfe [ 444.178367] [] ext4_mb_release_group_pa+0x40/0xfe [ 444.178370] [] ext4_mb_discard_group_preallocations+0x355/0x3eb [ 444.178374] [] ext4_mb_new_blocks+0x2de/0x3f4 [ 444.178378] [] ext4_ext_map_blocks+0xf63/0x1331 [ 444.178382] [] ? ext4_map_blocks+0xf5/0x1fa [ 444.178385] [] ext4_map_blocks+0x126/0x1fa [ 444.178388] [] mpage_da_map_and_submit+0xec/0x3b2 [ 444.178391] [] ext4_da_writepages+0x316/0x4b0 [ 444.178396] [] do_writepages+0x24/0x2d [ 444.178400] [] writeback_single_inode+0x135/0x2c3 [ 444.178403] [] writeback_sb_inodes+0x182/0x22c [ 444.178406] [] __writeback_inodes_wb+0x78/0xb9 [ 444.178409] [] writeback_inodes_wb+0x62/0x7c [ 444.178412] [] balance_dirty_pages_ratelimited_nr+0x3dc/0x686 [ 444.178417] [] generic_file_buffered_write+0x1c9/0x22d [ 444.178421] [] ? current_fs_time+0x27/0x2e [ 444.178424] [] __generic_file_aio_write+0x32e/0x35e [ 444.178428] [] generic_file_aio_write+0x66/0xc1 [ 444.178431] [] ext4_file_write+0x1f6/0x24f [ 444.178435] [] ? native_sched_clock+0x2d/0x5f [ 444.178439] [] ? fsnotify+0x216/0x26f [ 444.178443] [] ? local_clock+0x41/0x5a [ 444.178448] [] do_sync_write+0xcb/0x108 [ 444.178451] [] vfs_write+0xb8/0x157 [ 444.178453] [] sys_write+0x4d/0x77 [ 444.178456] [] system_call_fastpath+0x16/0x1b [ 444.178458] Code: 89 c2 4c 89 85 38 ff ff ff 48 8d 4d ec 41 0f b7 74 24 48 e8 3a d6 7a 00 4c 8b 85 38 ff ff ff 48 85 c0 74 50 48 8b 93 a0 00 00 00 [ 444.178471] 8b 52 28 8b 52 10 89 50 0c 48 8b 93 80 00 00 00 48 89 50 10 [ 444.178477] RIP [] perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 444.178481] RSP [ 444.178482] CR2: 0000000000000028 [ 444.178933] ---[ end trace a682372b42c1df35 ]--- [ 444.178940] ------------[ cut here ]------------ [ 444.178944] WARNING: at /c/wfg/linux/kernel/exit.c:900 do_exit+0x67/0x771() [ 444.178949] Hardware name: SandyBridge Platform [ 444.178956] Modules linked in: [ 444.178962] Pid: 5480, comm: dd Tainted: G D W 3.1.0+ #299 [ 444.178966] Call Trace: [ 444.178972] [] warn_slowpath_common+0x85/0x9d [ 444.178979] [] ? kmsg_dump+0x8a/0x10c [ 444.178983] [] warn_slowpath_null+0x1a/0x1c [ 444.178990] [] do_exit+0x67/0x771 [ 444.178996] [] ? kmsg_dump+0xfb/0x10c [ 444.179001] [] ? kmsg_dump+0x8a/0x10c [ 444.179013] [] oops_end+0xbe/0xc6 [ 444.179022] [] no_context+0x1f9/0x208 [ 444.179029] [] __bad_area_nosemaphore+0x1c9/0x1e9 [ 444.179035] [] bad_area+0x4a/0x51 [ 444.179041] [] do_page_fault+0x27e/0x431 [ 444.179049] [] ? perf_output_copy+0x71/0x71 [ 444.179055] [] ? perf_swevent_overflow+0x90/0xaa [ 444.179072] [] ? trace_hardirqs_off_thunk+0x3a/0x3c [ 444.179162] [] ? ext4_mb_discard_group_preallocations+0x315/0x3eb [ 444.179174] [] page_fault+0x25/0x30 [ 444.179178] [] ? ext4_mb_discard_group_preallocations+0x315/0x3eb [ 444.179222] [] ? perf_trace_ext4_mb_release_group_pa+0x81/0xd6 [ 444.179248] [] ? perf_trace_ext4_mb_release_group_pa+0x6e/0xd6 [ 444.179261] [] ? ext4_mb_release_group_pa+0x40/0xfe [ 444.179271] [] ext4_mb_release_group_pa+0x40/0xfe [ 444.179276] [] ext4_mb_discard_group_preallocations+0x355/0x3eb [ 444.179282] [] ext4_mb_new_blocks+0x2de/0x3f4 [ 444.179288] [] ext4_ext_map_blocks+0xf63/0x1331 [ 444.179295] [] ? ext4_map_blocks+0xf5/0x1fa [ 444.179300] [] ext4_map_blocks+0x126/0x1fa [ 444.179306] [] mpage_da_map_and_submit+0xec/0x3b2 [ 444.179311] [] ext4_da_writepages+0x316/0x4b0 [ 444.179317] [] do_writepages+0x24/0x2d [ 444.179477] [] writeback_single_inode+0x135/0x2c3 [ 444.179505] [] writeback_sb_inodes+0x182/0x22c [ 444.179515] [] __writeback_inodes_wb+0x78/0xb9 [ 444.179521] [] writeback_inodes_wb+0x62/0x7c [ 444.179526] [] balance_dirty_pages_ratelimited_nr+0x3dc/0x686 [ 444.179532] [] generic_file_buffered_write+0x1c9/0x22d [ 444.179535] [] ? current_fs_time+0x27/0x2e [ 444.179541] [] __generic_file_aio_write+0x32e/0x35e [ 444.179549] [] generic_file_aio_write+0x66/0xc1 [ 444.179555] [] ext4_file_write+0x1f6/0x24f [ 444.179560] [] ? native_sched_clock+0x2d/0x5f [ 444.179563] [] ? fsnotify+0x216/0x26f [ 444.179569] [] ? local_clock+0x41/0x5a [ 444.179577] [] do_sync_write+0xcb/0x108 [ 444.179581] [] vfs_write+0xb8/0x157 [ 444.179586] [] sys_write+0x4d/0x77 [ 444.179593] [] system_call_fastpath+0x16/0x1b [ 444.179597] ---[ end trace a682372b42c1df36 ]--- [ 444.179888] dd used greatest stack depth: 2088 bytes left [ 504.787849] INFO: rcu_sched_state detected stall on CPU 14 (t=60000 jiffies) [ 504.787854] INFO: rcu_sched_state detected stall on CPU 27 (t=60000 jiffies) [ 539.837210] BUG: spinlock lockup on CPU#14, dd/4796, ffff88081103c180 [ 539.845293] Pid: 4796, comm: dd Tainted: G D W 3.1.0+ #299 [ 539.852582] Call Trace: [ 539.855792] [] do_raw_spin_lock+0x10c/0x137 [ 539.862796] [] _raw_spin_lock+0x56/0x69 [ 539.869412] [] ? ext4_mb_find_by_goal+0xdb/0x1ce [ 539.876900] [] ext4_mb_find_by_goal+0xdb/0x1ce [ 539.883455] BUG: spinlock lockup on CPU#27, dd/5336, ffff88081103c080 [ 539.883458] Pid: 5336, comm: dd Tainted: G D W 3.1.0+ #299 [ 539.883459] Call Trace: [ 539.883464] [] do_raw_spin_lock+0x10c/0x137 [ 539.883467] [] _raw_spin_lock+0x56/0x69 [ 539.883471] [] ? ext4_mb_find_by_goal+0xdb/0x1ce [ 539.883474] [] ext4_mb_find_by_goal+0xdb/0x1ce [ 539.883477] [] ? ext4_mb_normalize_request+0x2f4/0x480 [ 539.883480] [] ext4_mb_regular_allocator+0x59/0x312 [ 539.883484] [] ext4_mb_new_blocks+0x197/0x3f4 [ 539.883487] [] ? ext4_ext_find_extent+0x130/0x2fb [ 539.883490] [] ? _raw_spin_unlock+0x2b/0x2f [ 539.883493] [] ext4_ext_map_blocks+0xf63/0x1331 [ 539.883499] [] ? ext4_map_blocks+0xf5/0x1fa [ 539.883502] [] ext4_map_blocks+0x126/0x1fa [ 539.883504] [] mpage_da_map_and_submit+0xec/0x3b2 [ 539.883507] [] ext4_da_writepages+0x316/0x4b0 [ 539.883513] [] do_writepages+0x24/0x2d [ 539.883520] [] writeback_single_inode+0x135/0x2c3 [ 539.883523] [] writeback_sb_inodes+0x182/0x22c [ 539.883526] [] __writeback_inodes_wb+0x78/0xb9 [ 539.883528] [] writeback_inodes_wb+0x62/0x7c [ 539.883532] [] balance_dirty_pages_ratelimited_nr+0x3dc/0x686 [ 539.883534] [] ? __mark_inode_dirty+0x2e/0x1cf [ 539.883539] [] generic_file_buffered_write+0x1c9/0x22d [ 539.883545] [] ? current_fs_time+0x27/0x2e [ 539.883548] [] __generic_file_aio_write+0x32e/0x35e [ 539.883552] [] generic_file_aio_write+0x66/0xc1 [ 539.883555] [] ext4_file_write+0x1f6/0x24f [ 539.883559] [] ? fsnotify+0x216/0x26f [ 539.883565] [] do_sync_write+0xcb/0x108 [ 539.883567] [] vfs_write+0xb8/0x157 [ 539.883570] [] sys_write+0x4d/0x77 [ 539.883574] [] system_call_fastpath+0x16/0x1b [ 540.125746] [] ? ext4_mb_normalize_request+0x2f4/0x480 [ 540.133817] [] ext4_mb_regular_allocator+0x59/0x312 [ 540.133820] [] ext4_mb_new_blocks+0x197/0x3f4 [ 540.133823] [] ? ext4_ext_find_extent+0x130/0x2fb [ 540.133829] [] ? _raw_spin_unlock+0x2b/0x2f [ 540.133831] [] ext4_ext_map_blocks+0xf63/0x1331 [ 540.133838] [] ? ext4_map_blocks+0xf5/0x1fa [ 540.133840] [] ext4_map_blocks+0x126/0x1fa [ 540.133843] [] mpage_da_map_and_submit+0xec/0x3b2 [ 540.133845] [] ext4_da_writepages+0x316/0x4b0 [ 540.133854] [] do_writepages+0x24/0x2d [ 540.133861] [] writeback_single_inode+0x135/0x2c3 [ 540.133863] [] writeback_sb_inodes+0x182/0x22c [ 540.133866] [] __writeback_inodes_wb+0x78/0xb9 [ 540.133869] [] writeback_inodes_wb+0x62/0x7c [ 540.133872] [] balance_dirty_pages_ratelimited_nr+0x3dc/0x686 [ 540.133875] [] ? __mark_inode_dirty+0x2e/0x1cf [ 540.133880] [] generic_file_buffered_write+0x1c9/0x22d [ 540.133886] [] ? current_fs_time+0x27/0x2e [ 540.133889] [] __generic_file_aio_write+0x32e/0x35e [ 540.133892] [] generic_file_aio_write+0x66/0xc1 [ 540.133896] [] ext4_file_write+0x1f6/0x24f [ 540.133900] [] ? fsnotify+0x216/0x26f [ 540.133905] [] do_sync_write+0xcb/0x108 [ 540.133908] [] vfs_write+0xb8/0x157 [ 540.133910] [] sys_write+0x4d/0x77 [ 540.133914] [] system_call_fastpath+0x16/0x1b [ 684.729866] INFO: rcu_sched_state detected stall on CPU 27 (t=240030 jiffies) [ 684.730858] INFO: rcu_sched_state detected stall on CPU 14 (t=240030 jiffies) [ 864.673871] INFO: rcu_sched_state detected stall on CPU 27 (t=420061 jiffies) [ 864.673877] INFO: rcu_sched_state detected stall on CPU 14 (t=420061 jiffies) [ 1044.615889] INFO: rcu_sched_state detected stall on CPU 27 (t=600092 jiffies) [ 1044.616884] INFO: rcu_sched_state detected stall on CPU 14 (t=600092 jiffies) [ 1224.558902] INFO: rcu_sched_state detected stall on CPU 27 (t=780123 jiffies) [ 1224.559899] INFO: rcu_sched_state detected stall on CPU 14 (t=780123 jiffies) [ 1404.501917] INFO: rcu_sched_state detected stall on CPU 14 (t=960154 jiffies) [ 1404.501922] INFO: rcu_sched_state detected stall on CPU 27 (t=960154 jiffies) [ 1584.443929] INFO: rcu_sched_state detected stall on CPU 27 (t=1140184 jiffies) [ 1584.443935] INFO: rcu_sched_state detected stall on CPU 14 (t=1140184 jiffies) [ 1764.386941] INFO: rcu_sched_state detected stall on CPU 14 (t=1320214 jiffies) [ 1764.386944] INFO: rcu_sched_state detected stall on CPU 27 (t=1320215 jiffies) [ 1944.328956] INFO: rcu_sched_state detected stall on CPU 14 (t=1500245 jiffies) [ 1944.328960] INFO: rcu_sched_state detected stall on CPU 27 (t=1500245 jiffies) [ 2124.270971] INFO: rcu_sched_state detected stall on CPU 14 (t=1680275 jiffies) [ 2124.270976] INFO: rcu_sched_state detected stall on CPU 27 (t=1680275 jiffies) [ 2304.212984] INFO: rcu_sched_state detected stall on CPU 14 (t=1860305 jiffies) [ 2304.213983] INFO: rcu_sched_state detected stall on CPU 27 (t=1860306 jiffies) [ 2484.155998] INFO: rcu_sched_state detected stall on CPU 27 (t=2040336 jiffies) [ 2484.156998] INFO: rcu_sched_state detected stall on CPU 14 (t=2040337 jiffies)