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BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff88813a412038 of 8 bytes by task 8431 on cpu 1:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6a7/0x700 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x169/0x180 kernel/trace/blktrace.c:1023
 trace_block_bio_remap include/trace/events/block.h:479 [inline]
 blk_partition_remap+0x170/0x1b0 block/blk-core.c:541
 submit_bio_noacct+0x394/0x810 block/blk-core.c:725
 submit_bio+0xfb/0x110 block/blk-core.c:827
 ext4_io_submit+0x86/0xa0 fs/ext4/page-io.c:378
 ext4_writepages+0xaca/0x1cf0 fs/ext4/inode.c:2854
 do_writepages+0x1db/0x350 mm/page-writeback.c:2469
 filemap_fdatawrite_wbc+0xd6/0xf0 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 filemap_write_and_wait_range+0xc2/0x1d0 mm/filemap.c:674
 __iomap_dio_rw+0x5dc/0x1000 fs/iomap/direct-io.c:573
 iomap_dio_rw+0x3c/0x80 fs/iomap/direct-io.c:690
 ext4_dio_read_iter fs/ext4/file.c:94 [inline]
 ext4_file_read_iter+0x20c/0x280 fs/ext4/file.c:145
 call_read_iter include/linux/fs.h:2185 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 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+0x63/0xcd

write to 0xffff88813a412038 of 8 bytes by task 8418 on cpu 0:
 relay_switch_subbuf+0x39d/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x6a7/0x700 kernel/trace/blktrace.c:276
 blk_add_trace_rq kernel/trace/blktrace.c:846 [inline]
 blk_add_trace_rq_insert+0x1b2/0x1c0 kernel/trace/blktrace.c:853
 trace_block_rq_insert include/trace/events/block.h:213 [inline]
 dd_insert_request+0x30b/0x570 block/mq-deadline.c:744
 dd_insert_requests+0xfc/0x140 block/mq-deadline.c:781
 blk_mq_sched_insert_requests+0xc0/0x2a0 block/blk-mq-sched.c:477
 blk_mq_dispatch_plug_list+0x1e9/0x2c0 block/blk-mq.c:2688
 blk_mq_flush_plug_list+0x2ea/0x340 block/blk-mq.c:2730
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1138
 blk_finish_plug+0x44/0x60 block/blk-core.c:1162
 __iomap_dio_rw+0xd27/0x1000 fs/iomap/direct-io.c:610
 iomap_dio_rw+0x3c/0x80 fs/iomap/direct-io.c:690
 ext4_dio_read_iter fs/ext4/file.c:94 [inline]
 ext4_file_read_iter+0x20c/0x280 fs/ext4/file.c:145
 call_read_iter include/linux/fs.h:2185 [inline]
 generic_file_splice_read+0xde/0x2b0 fs/splice.c:309
 do_splice_to fs/splice.c:793 [inline]
 splice_direct_to_actor+0x26c/0x620 fs/splice.c:865
 do_splice_direct+0xfb/0x180 fs/splice.c:974
 do_sendfile+0x3bf/0x910 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1309
 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+0x63/0xcd

value changed: 0x0000000000000038 -> 0x0000000000000030

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8418 Comm: syz-executor.3 Not tainted 6.0.0-syzkaller-12189-g19d17ab7c68b-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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