FYI, we noticed the below changes on https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2015.09.01b commit 73fd6575ce31757269a01963d1c164044e7114dd ("rcu: Don't disable preemption for Tiny and Tree RCU readers") +------------------------------------------+------------+------------+ | | ee00a7e165 | 73fd6575ce | +------------------------------------------+------------+------------+ | boot_successes | 21 | 0 | | boot_failures | 0 | 11 | | kernel_BUG_at_include/linux/pagemap.h | 0 | 11 | | invalid_opcode | 0 | 11 | | RIP:page_cache_get_speculative | 0 | 11 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 11 | | backtrace:vfs_write | 0 | 11 | | backtrace:SyS_write | 0 | 11 | | backtrace:populate_rootfs | 0 | 11 | | backtrace:kernel_init_freeable | 0 | 11 | +------------------------------------------+------------+------------+ [ 0.214529] Unpacking initramfs... [ 0.217998] ------------[ cut here ]------------ [ 0.217998] ------------[ cut here ]------------ [ 0.218935] kernel BUG at include/linux/pagemap.h:149! [ 0.218935] kernel BUG at include/linux/pagemap.h:149! [ 0.220009] invalid opcode: 0000 [#1] [ 0.220009] invalid opcode: 0000 [#1] DEBUG_PAGEALLOC DEBUG_PAGEALLOC [ 0.220009] CPU: 0 PID: 1 Comm: swapper Not tainted 4.2.0-rc1-00079-g73fd657 #1 [ 0.220009] CPU: 0 PID: 1 Comm: swapper Not tainted 4.2.0-rc1-00079-g73fd657 #1 [ 0.220009] task: ffff880013114040 ti: ffff880013118000 task.ti: ffff880013118000 [ 0.220009] task: ffff880013114040 ti: ffff880013118000 task.ti: ffff880013118000 [ 0.220009] RIP: 0010:[<ffffffff810e0862>] [ 0.220009] RIP: 0010:[<ffffffff810e0862>] [<ffffffff810e0862>] page_cache_get_speculative+0x20/0x70 [<ffffffff810e0862>] page_cache_get_speculative+0x20/0x70 [ 0.220009] RSP: 0000:ffff88001311b9d8 EFLAGS: 00010246 [ 0.220009] RSP: 0000:ffff88001311b9d8 EFLAGS: 00010246 [ 0.220009] RAX: 0000000080000000 RBX: ffffea000047bb00 RCX: 00000000fffffffc [ 0.220009] RAX: 0000000080000000 RBX: ffffea000047bb00 RCX: 00000000fffffffc [ 0.220009] RDX: 00000000fffffffc RSI: ffffffff81a33e20 RDI: ffffea000047bb00 [ 0.220009] RDX: 00000000fffffffc RSI: ffffffff81a33e20 RDI: ffffea000047bb00 [ 0.220009] RBP: ffff88001311b9d8 R08: 0000000000000000 R09: 0000000000000000 [ 0.220009] RBP: ffff88001311b9d8 R08: 0000000000000000 R09: 0000000000000000 [ 0.220009] R10: 0000000000006114 R11: 0000000000412bf2 R12: ffff88001353be80 [ 0.220009] R10: 0000000000006114 R11: 0000000000412bf2 R12: ffff88001353be80 [ 0.220009] R13: ffff88001348df88 R14: 0000000000000006 R15: 0000000000000006 [ 0.220009] R13: ffff88001348df88 R14: 0000000000000006 R15: 0000000000000006 [ 0.220009] FS: 0000000000000000(0000) GS:ffffffff81a20000(0000) knlGS:0000000000000000 [ 0.220009] FS: 0000000000000000(0000) GS:ffffffff81a20000(0000) knlGS:0000000000000000 [ 0.220009] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.220009] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.220009] CR2: 00000000ffffffff CR3: 0000000001a11000 CR4: 00000000000406b0 [ 0.220009] CR2: 00000000ffffffff CR3: 0000000001a11000 CR4: 00000000000406b0 [ 0.220009] Stack: [ 0.220009] Stack: [ 0.220009] ffff88001311ba08 [ 0.220009] ffff88001311ba08 ffffffff810e1a2e ffffffff810e1a2e 0000000000006114 0000000000006114 000000000000000f 000000000000000f [ 0.220009] 00000000000200d2 [ 0.220009] 00000000000200d2 ffff88001353be78 ffff88001353be78 ffff88001311ba58 ffff88001311ba58 ffffffff810e1ae6 ffffffff810e1ae6 [ 0.220009] 0000000000000002 [ 0.220009] 0000000000000002 0000000000000001 0000000000000001 0000000000000006 0000000000000006 0000000000006114 0000000000006114 [ 0.220009] Call Trace: [ 0.220009] Call Trace: [ 0.220009] [<ffffffff810e1a2e>] find_get_entry+0x4f/0x76 [ 0.220009] [<ffffffff810e1a2e>] find_get_entry+0x4f/0x76 [ 0.220009] [<ffffffff810e1ae6>] pagecache_get_page+0x28/0x182 [ 0.220009] [<ffffffff810e1ae6>] pagecache_get_page+0x28/0x182 [ 0.220009] [<ffffffff810e2d8b>] grab_cache_page_write_begin+0x27/0x3e [ 0.220009] [<ffffffff810e2d8b>] grab_cache_page_write_begin+0x27/0x3e [ 0.220009] [<ffffffff81139270>] simple_write_begin+0x27/0x75 [ 0.220009] [<ffffffff81139270>] simple_write_begin+0x27/0x75 [ 0.220009] [<ffffffff810e2e46>] generic_perform_write+0xa4/0x199 [ 0.220009] [<ffffffff810e2e46>] generic_perform_write+0xa4/0x199 [ 0.220009] [<ffffffff810a4981>] ? trace_hardirqs_on_caller+0x17e/0x199 [ 0.220009] [<ffffffff810a4981>] ? trace_hardirqs_on_caller+0x17e/0x199 [ 0.220009] [<ffffffff810e2fea>] __generic_file_write_iter+0xaf/0x154 [ 0.220009] [<ffffffff810e2fea>] __generic_file_write_iter+0xaf/0x154 [ 0.220009] [<ffffffff810a6a43>] ? lock_acquire+0x7f/0xac [ 0.220009] [<ffffffff810a6a43>] ? lock_acquire+0x7f/0xac [ 0.220009] [<ffffffff810e30e0>] generic_file_write_iter+0x51/0xbe [ 0.220009] [<ffffffff810e30e0>] generic_file_write_iter+0x51/0xbe [ 0.220009] [<ffffffff81b087cb>] ? initrd_load+0x3f/0x3f [ 0.220009] [<ffffffff81b087cb>] ? initrd_load+0x3f/0x3f [ 0.220009] [<ffffffff8111c1a8>] __vfs_write+0x77/0xa0 [ 0.220009] [<ffffffff8111c1a8>] __vfs_write+0x77/0xa0 [ 0.220009] [<ffffffff8111c2df>] vfs_write+0x92/0xb6 [ 0.220009] [<ffffffff8111c2df>] vfs_write+0x92/0xb6 [ 0.220009] [<ffffffff8111c3c3>] SyS_write+0x49/0x77 [ 0.220009] [<ffffffff8111c3c3>] SyS_write+0x49/0x77 [ 0.220009] [<ffffffff81b08a6b>] xwrite+0x29/0x5e [ 0.220009] [<ffffffff81b08a6b>] xwrite+0x29/0x5e [ 0.220009] [<ffffffff81b08acb>] do_copy+0x2b/0xba [ 0.220009] [<ffffffff81b08acb>] do_copy+0x2b/0xba [ 0.220009] [<ffffffff81b0886a>] write_buffer+0x24/0x36 [ 0.220009] [<ffffffff81b0886a>] write_buffer+0x24/0x36 [ 0.220009] [<ffffffff81b088a8>] flush_buffer+0x2c/0x87 [ 0.220009] [<ffffffff81b088a8>] flush_buffer+0x2c/0x87 [ 0.220009] [<ffffffff81b22c8a>] gunzip+0x256/0x2f0 [ 0.220009] [<ffffffff81b22c8a>] gunzip+0x256/0x2f0 [ 0.220009] [<ffffffff81b22a2a>] ? bunzip2+0x37e/0x37e [ 0.220009] [<ffffffff81b22a2a>] ? bunzip2+0x37e/0x37e [ 0.220009] [<ffffffff81b0887c>] ? write_buffer+0x36/0x36 [ 0.220009] [<ffffffff81b0887c>] ? write_buffer+0x36/0x36 [ 0.220009] [<ffffffff81b22a34>] ? nofill+0xa/0xa [ 0.220009] [<ffffffff81b22a34>] ? nofill+0xa/0xa [ 0.220009] [<ffffffff81b0911c>] unpack_to_rootfs+0x164/0x264 [ 0.220009] [<ffffffff81b0911c>] unpack_to_rootfs+0x164/0x264 [ 0.220009] [<ffffffff81b087cb>] ? initrd_load+0x3f/0x3f [ 0.220009] [<ffffffff81b087cb>] ? initrd_load+0x3f/0x3f [ 0.220009] [<ffffffff81b22a34>] ? nofill+0xa/0xa [ 0.220009] [<ffffffff81b22a34>] ? nofill+0xa/0xa [ 0.220009] [<ffffffff81b0921c>] ? unpack_to_rootfs+0x264/0x264 [ 0.220009] [<ffffffff81b0921c>] ? unpack_to_rootfs+0x264/0x264 [ 0.220009] [<ffffffff81b0927d>] populate_rootfs+0x61/0x10e [ 0.220009] [<ffffffff81b0927d>] populate_rootfs+0x61/0x10e [ 0.220009] [<ffffffff81b0921c>] ? unpack_to_rootfs+0x264/0x264 [ 0.220009] [<ffffffff81b0921c>] ? unpack_to_rootfs+0x264/0x264 [ 0.220009] [<ffffffff81b08047>] do_one_initcall+0x198/0x1ad [ 0.220009] [<ffffffff81b08047>] do_one_initcall+0x198/0x1ad [ 0.220009] [<ffffffff81b0822f>] kernel_init_freeable+0x1d3/0x256 [ 0.220009] [<ffffffff81b0822f>] kernel_init_freeable+0x1d3/0x256 [ 0.220009] [<ffffffff81435e7e>] ? rest_init+0x125/0x125 [ 0.220009] [<ffffffff81435e7e>] ? rest_init+0x125/0x125 [ 0.220009] [<ffffffff81435e87>] kernel_init+0x9/0xd5 [ 0.220009] [<ffffffff81435e87>] kernel_init+0x9/0xd5 [ 0.220009] [<ffffffff8144035f>] ret_from_fork+0x3f/0x70 [ 0.220009] [<ffffffff8144035f>] ret_from_fork+0x3f/0x70 [ 0.220009] [<ffffffff81435e7e>] ? rest_init+0x125/0x125 [ 0.220009] [<ffffffff81435e7e>] ? rest_init+0x125/0x125 [ 0.220009] Code: [ 0.220009] Code: 2c 2c a1 a1 00 00 01 01 e8 e8 bf bf 65 65 fc fc ff ff c9 c9 c3 c3 55 55 8b 8b 05 05 ff ff e7 e7 93 93 00 00 a9 a9 00 00 ff ff 1f 1f 00 00 48 48 89 89 e5 e5 74 74 02 02 0f 0f 0b 0b 8b 8b 05 05 ed ed e7 e7 93 93 00 00 a9 a9 ff ff ff ff ff ff 7f 7f 75 75 02 02 <0f> <0f> 0b 0b 48 48 8b 8b 17 17 48 48 89 89 f8 f8 80 80 e6 e6 80 80 74 74 0e 0e 48 48 8b 8b 47 47 30 30 48 48 8b 8b 17 17 80 80 [ 0.220009] RIP [ 0.220009] RIP [<ffffffff810e0862>] page_cache_get_speculative+0x20/0x70 [<ffffffff810e0862>] page_cache_get_speculative+0x20/0x70 [ 0.220009] RSP <ffff88001311b9d8> [ 0.220009] RSP <ffff88001311b9d8> [ 0.287220] ---[ end trace e01694ed94058ead ]--- [ 0.287220] ---[ end trace e01694ed94058ead ]--- Thanks, Ying Huang