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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+0x95d/0xb10 drivers/scsi/virtio_scsi.c:590
 scsi_dispatch_cmd+0x54e/0xbf0 drivers/scsi/scsi_lib.c:1516
 scsi_queue_rq+0x414c/0x4820 drivers/scsi/scsi_lib.c:1752
 blk_mq_dispatch_rq_list+0x1495/0x41e0 block/blk-mq.c:1902
 __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:2020
 __blk_mq_delay_run_hw_queue+0x13e/0x830 block/blk-mq.c:2096
 blk_mq_run_hw_queue+0x4d7/0x7d0 block/blk-mq.c:2144
 blk_mq_sched_insert_requests+0x4e5/0x760 block/blk-mq-sched.c:493
 blk_mq_dispatch_plug_list+0x66b/0x880 block/blk-mq.c:2604
 blk_mq_flush_plug_list+0x759/0x8e0 block/blk-mq.c:2646
 __blk_flush_plug+0x5f6/0x680 block/blk-core.c:1153
 blk_flush_plug include/linux/blkdev.h:1028 [inline]
 writeback_sb_inodes+0x13fb/0x2ce0 fs/fs-writeback.c:1882
 wb_writeback+0x551/0xe30 fs/fs-writeback.c:2039
 wb_do_writeback+0x25a/0x11c0 fs/fs-writeback.c:2182
 wb_workfn+0x194/0x600 fs/fs-writeback.c:2222
 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

Uninit was created at:
 __alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5556
 alloc_pages+0xaae/0xd80 mm/mempolicy.c:2270
 folio_alloc+0x3e/0x120 mm/mempolicy.c:2280
 filemap_alloc_folio mm/filemap.c:970 [inline]
 __filemap_get_folio+0xe59/0x1b00 mm/filemap.c:1970
 pagecache_get_page+0x4a/0x4d0 mm/folio-compat.c:104
 grab_cache_page_write_begin+0x51/0x70 mm/folio-compat.c:116
 ext4_write_begin+0x3a4/0x3060 fs/ext4/inode.c:1188
 ext4_da_write_begin+0x609/0x1190 fs/ext4/inode.c:2972
 generic_perform_write+0x3f1/0xbf0 mm/filemap.c:3738
 ext4_buffered_write_iter+0x5ec/0xbe0 fs/ext4/file.c:270
 ext4_file_write_iter+0x155f/0x3630
 call_write_iter include/linux/fs.h:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x830/0x1570 fs/read_write.c:578
 ksys_write+0x21b/0x4e0 fs/read_write.c:631
 __do_sys_write fs/read_write.c:643 [inline]
 __se_sys_write fs/read_write.c:640 [inline]
 __ia32_sys_write+0x8d/0xd0 fs/read_write.c:640
 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 116-4095 of 4096 are uninitialized
Memory access of size 4096 starts at ffff88803adc9000

CPU: 0 PID: 27 Comm: kworker/u4:1 Not tainted 6.0.0-rc5-syzkaller-48539-g523d2ce66d07 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Workqueue: writeback wb_workfn (flush-8:0)
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