================================================================== BUG: KCSAN: data-race in __mod_timer / blk_add_timer write to 0xffff888101941b08 of 8 bytes by task 5194 on cpu 0: __mod_timer+0x721/0xbe0 kernel/time/timer.c:1050 mod_timer+0x1b/0x20 kernel/time/timer.c:1106 blk_add_timer+0x191/0x1a0 block/blk-timeout.c:164 blk_mq_start_request+0x115/0x1b0 block/blk-mq.c:726 loop_queue_rq+0x3b/0x120 drivers/block/loop.c:2004 blk_mq_dispatch_rq_list+0x5b0/0xfa0 block/blk-mq.c:1369 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:186 [inline] blk_mq_do_dispatch_sched+0x370/0x610 block/blk-mq-sched.c:199 __blk_mq_sched_dispatch_requests+0x21e/0x2c0 block/blk-mq-sched.c:310 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:341 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1488 __blk_mq_delay_run_hw_queue+0x163/0x2d0 block/blk-mq.c:1565 blk_mq_run_hw_queue+0x22c/0x250 block/blk-mq.c:1618 blk_mq_sched_insert_requests+0x13f/0x200 block/blk-mq-sched.c:491 blk_mq_flush_plug_list+0x2f5/0x3c0 block/blk-mq.c:1942 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1749 blk_finish_plug+0x44/0x60 block/blk-core.c:1766 read_pages+0x2d9/0x530 mm/readahead.c:150 page_cache_ra_unbounded+0x3a8/0x400 mm/readahead.c:238 do_page_cache_ra mm/readahead.c:267 [inline] force_page_cache_ra+0x236/0x270 mm/readahead.c:298 page_cache_sync_ra+0xb5/0xd0 mm/readahead.c:572 page_cache_sync_readahead include/linux/pagemap.h:840 [inline] filemap_get_pages mm/filemap.c:2375 [inline] filemap_read+0x380/0x1210 mm/filemap.c:2458 generic_file_read_iter+0x84/0x3e0 mm/filemap.c:2609 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1727 call_read_iter include/linux/fs.h:1971 [inline] new_sync_read fs/read_write.c:415 [inline] vfs_read+0x565/0x5d0 fs/read_write.c:496 ksys_read+0xce/0x180 fs/read_write.c:634 __do_sys_read fs/read_write.c:644 [inline] __se_sys_read fs/read_write.c:642 [inline] __x64_sys_read+0x3e/0x50 fs/read_write.c:642 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff888101941b08 of 8 bytes by task 5191 on cpu 1: blk_add_timer+0x125/0x1a0 include/linux/list.h:821 blk_mq_start_request+0x115/0x1b0 block/blk-mq.c:726 loop_queue_rq+0x3b/0x120 drivers/block/loop.c:2004 blk_mq_dispatch_rq_list+0x5b0/0xfa0 block/blk-mq.c:1369 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:186 [inline] blk_mq_do_dispatch_sched+0x370/0x610 block/blk-mq-sched.c:199 __blk_mq_sched_dispatch_requests+0x21e/0x2c0 block/blk-mq-sched.c:310 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:341 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1488 __blk_mq_delay_run_hw_queue+0x163/0x2d0 block/blk-mq.c:1565 blk_mq_run_hw_queue+0x22c/0x250 block/blk-mq.c:1618 blk_mq_sched_insert_requests+0x13f/0x200 block/blk-mq-sched.c:491 blk_mq_flush_plug_list+0x2f5/0x3c0 block/blk-mq.c:1942 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1749 blk_finish_plug+0x44/0x60 block/blk-core.c:1766 read_pages+0x2d9/0x530 mm/readahead.c:150 page_cache_ra_unbounded+0x3a8/0x400 mm/readahead.c:238 do_page_cache_ra mm/readahead.c:267 [inline] force_page_cache_ra+0x236/0x270 mm/readahead.c:298 page_cache_sync_ra+0xb5/0xd0 mm/readahead.c:572 page_cache_sync_readahead include/linux/pagemap.h:840 [inline] filemap_get_pages mm/filemap.c:2375 [inline] filemap_read+0x380/0x1210 mm/filemap.c:2458 generic_file_read_iter+0x84/0x3e0 mm/filemap.c:2609 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1727 call_read_iter include/linux/fs.h:1971 [inline] new_sync_read fs/read_write.c:415 [inline] vfs_read+0x565/0x5d0 fs/read_write.c:496 ksys_read+0xce/0x180 fs/read_write.c:634 __do_sys_read fs/read_write.c:644 [inline] __se_sys_read fs/read_write.c:642 [inline] __x64_sys_read+0x3e/0x50 fs/read_write.c:642 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 5191 Comm: systemd-udevd Tainted: G W 5.12.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================