==================================================================
BUG: KCSAN: data-race in relay_switch_subbuf / relay_switch_subbuf

write to 0xffff888116449c38 of 8 bytes by task 19268 on cpu 0:
 relay_switch_subbuf+0x39e/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66a/0x730 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x165/0x180 kernel/trace/blktrace.c:1021
 trace_block_bio_remap include/trace/events/block.h:507 [inline]
 blk_partition_remap block/blk-core.c:571 [inline]
 submit_bio_noacct+0x7dd/0x830 block/blk-core.c:762
 submit_bio+0x218/0x230 block/blk-core.c:879
 iomap_dio_submit_bio fs/iomap/direct-io.c:80 [inline]
 iomap_dio_bio_iter+0xab0/0xc40 fs/iomap/direct-io.c:418
 __iomap_dio_rw+0x8bd/0x1090 fs/iomap/direct-io.c:660
 iomap_dio_rw+0x40/0x90 fs/iomap/direct-io.c:749
 ext4_dio_read_iter fs/ext4/file.c:94 [inline]
 ext4_file_read_iter+0x220/0x2a0 fs/ext4/file.c:145
 call_read_iter include/linux/fs.h:2102 [inline]
 copy_splice_read+0x3a4/0x5d0 fs/splice.c:365
 do_splice_read fs/splice.c:984 [inline]
 splice_direct_to_actor+0x28e/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

write to 0xffff888116449c38 of 8 bytes by task 19292 on cpu 1:
 relay_switch_subbuf+0x39e/0x3b0 kernel/relay.c:708
 relay_reserve include/linux/relay.h:248 [inline]
 __blk_add_trace+0x66a/0x730 kernel/trace/blktrace.c:276
 blk_add_trace_bio_remap+0x165/0x180 kernel/trace/blktrace.c:1021
 trace_block_bio_remap include/trace/events/block.h:507 [inline]
 blk_partition_remap block/blk-core.c:571 [inline]
 submit_bio_noacct+0x7dd/0x830 block/blk-core.c:762
 submit_bio+0x218/0x230 block/blk-core.c:879
 swap_writepage_bdev_async mm/page_io.c:371 [inline]
 __swap_writepage+0x612/0xc50 mm/page_io.c:389
 swap_writepage+0xa9/0x160 mm/page_io.c:209
 pageout mm/vmscan.c:660 [inline]
 shrink_folio_list+0x1858/0x2460 mm/vmscan.c:1323
 shrink_inactive_list mm/vmscan.c:1926 [inline]
 shrink_list mm/vmscan.c:2163 [inline]
 shrink_lruvec+0xbbc/0x1640 mm/vmscan.c:5687
 shrink_node_memcgs mm/vmscan.c:5873 [inline]
 shrink_node+0xa78/0x15a0 mm/vmscan.c:5908
 shrink_zones mm/vmscan.c:6152 [inline]
 do_try_to_free_pages+0x3cc/0xca0 mm/vmscan.c:6214
 try_to_free_mem_cgroup_pages+0x1eb/0x4e0 mm/vmscan.c:6529
 try_charge_memcg+0x279/0xd10 mm/memcontrol.c:2783
 obj_cgroup_charge_pages+0xbd/0x1d0 mm/memcontrol.c:3302
 __memcg_kmem_charge_page+0x9d/0x170 mm/memcontrol.c:3328
 __alloc_pages+0x1bc/0x360 mm/page_alloc.c:4592
 alloc_pages_mpol+0xb1/0x1e0 mm/mempolicy.c:2264
 alloc_pages+0xe1/0x100 mm/mempolicy.c:2335
 vm_area_alloc_pages mm/vmalloc.c:3545 [inline]
 __vmalloc_area_node mm/vmalloc.c:3621 [inline]
 __vmalloc_node_range+0x6f2/0xee0 mm/vmalloc.c:3802
 kvmalloc_node+0x121/0x170 mm/util.c:659
 kvmalloc include/linux/slab.h:766 [inline]
 xt_alloc_table_info+0x3d/0x80 net/netfilter/x_tables.c:1193
 do_replace net/ipv6/netfilter/ip6_tables.c:1139 [inline]
 do_ip6t_set_ctl+0x63f/0x1800 net/ipv6/netfilter/ip6_tables.c:1636
 nf_setsockopt+0x195/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x126/0x140 net/ipv6/ipv6_sockglue.c:999
 dccp_setsockopt+0xe1/0xc40 net/dccp/proto.c:579
 sock_common_setsockopt+0x64/0x80 net/core/sock.c:3727
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d8/0x250 net/socket.c:2334
 __do_sys_setsockopt net/socket.c:2343 [inline]
 __se_sys_setsockopt net/socket.c:2340 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x0000000000000030 -> 0x0000000000000040

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19292 Comm: syz-executor.3 Not tainted 6.9.0-rc1-syzkaller-00061-g8d025e2092e2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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syz-executor.3 (19292) used greatest stack depth: 7968 bytes left