Hello, syzbot found the following crash on: HEAD commit: af7b4801 Merge git://git.kernel.org/pub/scm/linux/kernel/g.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=15fe909e100000 kernel config: https://syzkaller.appspot.com/x/.config?x=b366fd92adf6f8b4 dashboard link: https://syzkaller.appspot.com/bug?extid=2ad52db2be557736dd15 compiler: gcc (GCC) 9.0.0 20181231 (experimental) IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+2ad52db2be557736dd15@xxxxxxxxxxxxxxxxxxxxxxxxx process_one_work+0x965/0x16a0 kernel/workqueue.c:2269 worker_thread+0x96/0xe10 kernel/workqueue.c:2415 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u4:1/21 caller is ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.7.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 check_preemption_disabled lib/smp_processor_id.c:47 [inline] debug_smp_processor_id.cold+0x88/0x9b lib/smp_processor_id.c:57 ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 ext4_ext_map_blocks+0x2044/0x3410 fs/ext4/extents.c:4244 ext4_map_blocks+0x4cb/0x1640 fs/ext4/inode.c:626 mpage_map_one_extent fs/ext4/inode.c:2377 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2430 [inline] ext4_writepages+0x1ab7/0x3400 fs/ext4/inode.c:2782 do_writepages+0xfa/0x2a0 mm/page-writeback.c:2354 __writeback_single_inode+0x12a/0x1410 fs/fs-writeback.c:1452 writeback_sb_inodes+0x515/0xdd0 fs/fs-writeback.c:1716 __writeback_inodes_wb+0xc3/0x250 fs/fs-writeback.c:1785 wb_writeback+0x910/0xd90 fs/fs-writeback.c:1894 wb_check_old_data_flush fs/fs-writeback.c:1996 [inline] wb_do_writeback fs/fs-writeback.c:2049 [inline] wb_workfn+0xadf/0x10d0 fs/fs-writeback.c:2078 process_one_work+0x965/0x16a0 kernel/workqueue.c:2269 worker_thread+0x96/0xe10 kernel/workqueue.c:2415 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u4:1/21 caller is ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.7.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 check_preemption_disabled lib/smp_processor_id.c:47 [inline] debug_smp_processor_id.cold+0x88/0x9b lib/smp_processor_id.c:57 ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 ext4_ext_map_blocks+0x2044/0x3410 fs/ext4/extents.c:4244 ext4_map_blocks+0x4cb/0x1640 fs/ext4/inode.c:626 mpage_map_one_extent fs/ext4/inode.c:2377 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2430 [inline] ext4_writepages+0x1ab7/0x3400 fs/ext4/inode.c:2782 do_writepages+0xfa/0x2a0 mm/page-writeback.c:2354 __writeback_single_inode+0x12a/0x1410 fs/fs-writeback.c:1452 writeback_sb_inodes+0x515/0xdd0 fs/fs-writeback.c:1716 __writeback_inodes_wb+0xc3/0x250 fs/fs-writeback.c:1785 wb_writeback+0x910/0xd90 fs/fs-writeback.c:1894 wb_check_old_data_flush fs/fs-writeback.c:1996 [inline] wb_do_writeback fs/fs-writeback.c:2049 [inline] wb_workfn+0xadf/0x10d0 fs/fs-writeback.c:2078 process_one_work+0x965/0x16a0 kernel/workqueue.c:2269 worker_thread+0x96/0xe10 kernel/workqueue.c:2415 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u4:1/21 caller is ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.7.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: writeback wb_workfn (flush-8:0) Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 check_preemption_disabled lib/smp_processor_id.c:47 [inline] debug_smp_processor_id.cold+0x88/0x9b lib/smp_processor_id.c:57 ext4_mb_new_blocks+0xa77/0x3b30 fs/ext4/mballoc.c:4711 ext4_ext_map_blocks+0x2044/0x3410 fs/ext4/extents.c:4244 ext4_map_blocks+0x4cb/0x1640 fs/ext4/inode.c:626 mpage_map_one_extent fs/ext4/inode.c:2377 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2430 [inline] ext4_writepages+0x1ab7/0x3400 fs/ext4/inode.c:2782 do_writepages+0xfa/0x2a0 mm/page-writeback.c:2354 __writeback_single_inode+0x12a/0x1410 fs/fs-writeback.c:1452 writeback_sb_inodes+0x515/0xdd0 fs/fs-writeback.c:1716 __writeback_inodes_wb+0xc3/0x250 fs/fs-writeback.c:1785 wb_writeback+0x910/0xd90 fs/fs-writeback.c:1894 wb_check_old_data_flush fs/fs-writeback.c:1996 [inline] wb_do_writeback fs/fs-writeback.c:2049 [inline] wb_workfn+0xadf/0x10d0 fs/fs-writeback.c:2078 process_one_work+0x965/0x16a0 kernel/workqueue.c:2269 worker_thread+0x96/0xe10 kernel/workqueue.c:2415 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 --- This bug is generated by a bot. 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