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BUG: KCSAN: data-race in random_recv_done / virtio_read

write to 0xffff8881020294cc of 4 bytes by task 17355 on cpu 0:
 request_entropy drivers/char/hw_random/virtio-rng.c:56 [inline]
 copy_data drivers/char/hw_random/virtio-rng.c:74 [inline]
 virtio_read+0x190/0x430 drivers/char/hw_random/virtio-rng.c:92
 rng_get_data drivers/char/hw_random/core.c:191 [inline]
 rng_dev_read+0x1b4/0x630 drivers/char/hw_random/core.c:228
 vfs_read+0x1a1/0x6a0 fs/read_write.c:480
 ksys_read+0xe8/0x1a0 fs/read_write.c:620
 __do_sys_read fs/read_write.c:630 [inline]
 __se_sys_read fs/read_write.c:628 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881020294cc of 4 bytes by interrupt on cpu 1:
 random_recv_done+0x58/0x80 drivers/char/hw_random/virtio-rng.c:45
 vring_interrupt+0x15d/0x180 drivers/virtio/virtio_ring.c:2148
 __handle_irq_event_percpu+0x92/0x400 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x60/0xf0 kernel/irq/handle.c:210
 handle_edge_irq+0x17e/0x5a0 kernel/irq/chip.c:817
 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
 handle_irq arch/x86/kernel/irq.c:231 [inline]
 __common_interrupt+0x60/0x100 arch/x86/kernel/irq.c:250
 common_interrupt+0x9a/0xc0 arch/x86/kernel/irq.c:240
 asm_common_interrupt+0x1e/0x40
 _find_next_bit+0x53/0x190 lib/find_bit.c:41
 find_next_zero_bit include/linux/find.h:102 [inline]
 __sbitmap_get_word lib/sbitmap.c:145 [inline]
 sbitmap_find_bit_in_index lib/sbitmap.c:177 [inline]
 __sbitmap_get lib/sbitmap.c:206 [inline]
 sbitmap_get+0x1cf/0x470 lib/sbitmap.c:231
 __sbitmap_queue_get+0x11/0x20 lib/sbitmap.c:504
 __blk_mq_alloc_driver_tag block/blk-mq.c:1584 [inline]
 __blk_mq_get_driver_tag+0x1ad/0x460 block/blk-mq.c:1594
 blk_mq_get_driver_tag block/blk-mq.h:283 [inline]
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:153 [inline]
 blk_mq_do_dispatch_sched+0x395/0x780 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x1ca/0x270
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:1981
 __blk_mq_delay_run_hw_queue+0x194/0x390 block/blk-mq.c:2058
 blk_mq_run_hw_queue+0x180/0x310 block/blk-mq.c:2109
 blk_mq_sched_insert_requests+0x1cb/0x2a0 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2604
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2646
 blk_add_rq_to_plug+0x13f/0x390 block/blk-mq.c:2707
 blk_mq_submit_bio+0x91c/0xe40 block/blk-mq.c:2856
 __submit_bio+0x130/0x330 block/blk-core.c:666
 __submit_bio_noacct_mq block/blk-core.c:743 [inline]
 submit_bio_noacct_nocheck+0x425/0x480 block/blk-core.c:760
 submit_bio_noacct+0x6c4/0x820 block/blk-core.c:867
 submit_bio+0x139/0x150
 ext4_io_submit fs/ext4/page-io.c:378 [inline]
 io_submit_add_bh fs/ext4/page-io.c:420 [inline]
 ext4_bio_write_page+0x43d/0x8a0 fs/ext4/page-io.c:546
 mpage_submit_page fs/ext4/inode.c:2090 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2336 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2475 [inline]
 ext4_writepages+0xe76/0x1970 fs/ext4/inode.c:2804
 do_writepages+0x1db/0x350 mm/page-writeback.c:2352
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0x93/0xc0 mm/filemap.c:454
 __ext4_ioctl fs/ext4/ioctl.c:1338 [inline]
 ext4_ioctl+0xcbf/0x20a0 fs/ext4/ioctl.c:1578
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000040 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17362 Comm: syz-executor.0 Tainted: G        W         5.18.0-rc4-syzkaller-00036-gcf424ef014ac-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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