syzbot

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BUG: KCSAN: data-race in blk_mq_sched_dispatch_requests / blk_mq_sched_dispatch_requests

read-write to 0xffff888100c0ef50 of 8 bytes by task 31591 on cpu 0:
 blk_mq_sched_dispatch_requests+0x8a/0x100 block/blk-mq-sched.c:327
 blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2252
 blk_mq_flush_plug_list+0x7b6/0xdc0 block/blk-mq.c:2800
 __blk_flush_plug+0x210/0x260 block/blk-core.c:1142
 blk_finish_plug+0x47/0x60 block/blk-core.c:1166
 ext4_do_writepages+0x1bc7/0x2100 fs/ext4/inode.c:2736
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2774
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
 __filemap_fdatawrite_range mm/filemap.c:420 [inline]
 file_write_and_wait_range+0xf4/0x190 mm/filemap.c:778
 ext4_sync_file+0x133/0x6c0 fs/ext4/fsync.c:158
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2653 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0x297/0xe10
 do_iter_write+0x4ad/0x770 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3c4/0x980 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read-write to 0xffff888100c0ef50 of 8 bytes by task 31566 on cpu 1:
 blk_mq_sched_dispatch_requests+0x8a/0x100 block/blk-mq-sched.c:327
 blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2252
 blk_mq_flush_plug_list+0x7b6/0xdc0 block/blk-mq.c:2800
 __blk_flush_plug+0x210/0x260 block/blk-core.c:1142
 blk_finish_plug+0x47/0x60 block/blk-core.c:1166
 ext4_do_writepages+0x1bc7/0x2100 fs/ext4/inode.c:2736
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2774
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
 __filemap_fdatawrite_range mm/filemap.c:420 [inline]
 file_write_and_wait_range+0xf4/0x190 mm/filemap.c:778
 ext4_sync_file+0x133/0x6c0 fs/ext4/fsync.c:158
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2653 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0x297/0xe10
 do_iter_write+0x4ad/0x770 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3c4/0x980 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x000000000000abc3 -> 0x000000000000abc4

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31566 Comm: syz-executor.3 Tainted: G        W          6.7.0-rc3-syzkaller-00048-ge8f60209d6cf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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