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BUG: KMSAN: uninit-value in kmsan_handle_dma_page mm/kmsan/kmsan_hooks.c:348 [inline]
BUG: KMSAN: uninit-value in kmsan_handle_dma+0x7f/0x90 mm/kmsan/kmsan_hooks.c:374
CPU: 0 PID: 3277 Comm: kworker/0:1H Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kblockd blk_mq_run_work_fn
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 kmsan_internal_check_memory+0x238/0x3d0 mm/kmsan/kmsan.c:423
 kmsan_handle_dma_page mm/kmsan/kmsan_hooks.c:348 [inline]
 kmsan_handle_dma+0x7f/0x90 mm/kmsan/kmsan_hooks.c:374
 vring_map_one_sg+0x4d1/0x660 drivers/virtio/virtio_ring.c:336
 virtqueue_add_split drivers/virtio/virtio_ring.c:491 [inline]
 virtqueue_add+0x32fd/0x5790 drivers/virtio/virtio_ring.c:1714
 virtqueue_add_sgs+0x319/0x330 drivers/virtio/virtio_ring.c:1748
 __virtscsi_add_cmd drivers/scsi/virtio_scsi.c:447 [inline]
 virtscsi_add_cmd+0x888/0xb20 drivers/scsi/virtio_scsi.c:481
 virtscsi_queuecommand+0xe7e/0x1090 drivers/scsi/virtio_scsi.c:578
 scsi_dispatch_cmd drivers/scsi/scsi_lib.c:1554 [inline]
 scsi_queue_rq+0x41c5/0x4d20 drivers/scsi/scsi_lib.c:1689
 blk_mq_dispatch_rq_list+0xf81/0x2850 block/blk-mq.c:1246
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:115 [inline]
 blk_mq_sched_dispatch_requests+0xbe0/0x1840 block/blk-mq-sched.c:216
 __blk_mq_run_hw_queue+0x171/0x3a0 block/blk-mq.c:1382
 blk_mq_run_work_fn+0x7e/0xb0 block/blk-mq.c:1641
 process_one_work+0x1555/0x1f40 kernel/workqueue.c:2266
 worker_thread+0xef6/0x2450 kernel/workqueue.c:2412
 kthread+0x4b5/0x4f0 kernel/kthread.c:256
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:353

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:307 [inline]
 kmsan_alloc_page+0x12a/0x310 mm/kmsan/kmsan_shadow.c:336
 __alloc_pages_nodemask+0x5712/0x5e80 mm/page_alloc.c:4775
 alloc_pages_current+0x67d/0x990 mm/mempolicy.c:2211
 alloc_pages include/linux/gfp.h:534 [inline]
 __page_cache_alloc+0x95/0x310 mm/filemap.c:959
 pagecache_get_page+0xab7/0x1250 mm/filemap.c:1649
 find_or_create_page include/linux/pagemap.h:310 [inline]
 grow_dev_page fs/buffer.c:989 [inline]
 grow_buffers fs/buffer.c:1058 [inline]
 __getblk_slow fs/buffer.c:1085 [inline]
 __getblk_gfp+0x4bb/0xfc0 fs/buffer.c:1362
 sb_getblk_gfp include/linux/buffer_head.h:332 [inline]
 ext4_ext_split fs/ext4/extents.c:1077 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1368 [inline]
 ext4_ext_insert_extent+0x315f/0x8600 fs/ext4/extents.c:2053
 ext4_ext_map_blocks+0x7731/0xdb20 fs/ext4/extents.c:4466
 ext4_map_blocks+0x12fb/0x2e60 fs/ext4/inode.c:622
 _ext4_get_block+0x2b4/0x9c0 fs/ext4/inode.c:773
 ext4_get_block_unwritten+0x9d/0xb0 fs/ext4/inode.c:804
 ext4_block_write_begin+0x958/0x1cf0 fs/ext4/inode.c:1054
 ext4_write_begin+0xc2f/0x2010 fs/ext4/ext4_jbd2.h:509
 generic_perform_write+0x3d4/0x9a0 mm/filemap.c:3287
 ext4_buffered_write_iter+0x795/0xac0 fs/ext4/file.c:270
 ext4_file_write_iter+0x1330/0x2c70 fs/ext4/file.c:491
 call_write_iter include/linux/fs.h:1902 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0xa5a/0xca0 fs/read_write.c:496
 vfs_write+0x44a/0x8f0 fs/read_write.c:558
 ksys_write+0x267/0x450 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __ia32_sys_write+0xdb/0x120 fs/read_write.c:620
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139

Bytes 8-11 of 4096 are uninitialized
Memory access of size 4096 starts at ffff91a28f574000
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