=====================================================
BUG: KMSAN: uninit-value in vring_map_one_sg drivers/virtio/virtio_ring.c:362 [inline]
BUG: KMSAN: uninit-value in virtqueue_add_split drivers/virtio/virtio_ring.c:585 [inline]
BUG: KMSAN: uninit-value in virtqueue_add+0x1d96/0x6270 drivers/virtio/virtio_ring.c:2096
 vring_map_one_sg drivers/virtio/virtio_ring.c:362 [inline]
 virtqueue_add_split drivers/virtio/virtio_ring.c:585 [inline]
 virtqueue_add+0x1d96/0x6270 drivers/virtio/virtio_ring.c:2096
 virtqueue_add_sgs+0x182/0x1a0 drivers/virtio/virtio_ring.c:2130
 __virtscsi_add_cmd drivers/scsi/virtio_scsi.c:459 [inline]
 virtscsi_add_cmd+0x861/0xb00 drivers/scsi/virtio_scsi.c:493
 virtscsi_queuecommand+0x900/0xb00 drivers/scsi/virtio_scsi.c:590
 scsi_dispatch_cmd+0x54e/0xbf0 drivers/scsi/scsi_lib.c:1524
 scsi_queue_rq+0x4088/0x4720 drivers/scsi/scsi_lib.c:1760
 blk_mq_dispatch_rq_list+0x1495/0x41e0 block/blk-mq.c:1986
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:173 [inline]
 blk_mq_do_dispatch_sched+0xdd1/0x16d0 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x442/0x630
 blk_mq_sched_dispatch_requests+0x159/0x2c0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0xee/0x260 block/blk-mq.c:2104
 __blk_mq_delay_run_hw_queue+0x149/0x6d0 block/blk-mq.c:2180
 blk_mq_run_hw_queue+0x4d7/0x7d0 block/blk-mq.c:2228
 blk_mq_sched_insert_requests+0x4e5/0x760 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x66b/0x880 block/blk-mq.c:2688
 blk_mq_flush_plug_list+0x759/0x8e0 block/blk-mq.c:2730
 __blk_flush_plug+0x5f6/0x680 block/blk-core.c:1138
 blk_finish_plug+0x71/0x90 block/blk-core.c:1162
 wb_writeback+0xdc3/0xe30 fs/fs-writeback.c:2078
 wb_do_writeback+0x25a/0x11c0 fs/fs-writeback.c:2187
 wb_workfn+0x194/0x600 fs/fs-writeback.c:2227
 process_one_work+0xb27/0x13e0 kernel/workqueue.c:2289
 worker_thread+0x1076/0x1d60 kernel/workqueue.c:2436
 kthread+0x31b/0x430 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Uninit was created at:
 __alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5577
 alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285
 folio_alloc+0x3e/0x120 mm/mempolicy.c:2295
 filemap_alloc_folio mm/filemap.c:971 [inline]
 __filemap_get_folio+0xe59/0x1b00 mm/filemap.c:1965
 pagecache_get_page+0x4a/0x2f0 mm/folio-compat.c:110
 grab_cache_page_write_begin+0x51/0x70 mm/folio-compat.c:122
 mext_page_double_lock+0x112/0x8e0 fs/ext4/move_extent.c:141
 move_extent_per_page+0x8e7/0x3ac0 fs/ext4/move_extent.c:305
 ext4_move_extents+0xfeb/0x1750 fs/ext4/move_extent.c:672
 __ext4_ioctl fs/ext4/ioctl.c:1351 [inline]
 ext4_ioctl+0x612b/0x8c40 fs/ext4/ioctl.c:1607
 ext4_compat_ioctl+0x702/0x800 fs/ext4/ioctl.c:1683
 __do_compat_sys_ioctl fs/ioctl.c:968 [inline]
 __se_compat_sys_ioctl+0x781/0xfa0 fs/ioctl.c:910
 __ia32_compat_sys_ioctl+0x8f/0xd0 fs/ioctl.c:910
 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
 __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
 entry_SYSENTER_compat_after_hwframe+0x70/0x82

Bytes 8-4095 of 4096 are uninitialized
Memory access of size 4096 starts at ffff88801e3d8000

CPU: 0 PID: 1556 Comm: kworker/u4:0 Not tainted 6.1.0-rc2-syzkaller-61959-gbe8b0d020631 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Workqueue: writeback wb_workfn (flush-8:0)
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