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BUG: KMSAN: uninit-value in is_folio_zero_filled mm/page_io.c:188 [inline]
BUG: KMSAN: uninit-value in swap_writeout+0x468/0x1380 mm/page_io.c:263
 is_folio_zero_filled mm/page_io.c:188 [inline]
 swap_writeout+0x468/0x1380 mm/page_io.c:263
 shmem_writeout+0x1ac0/0x1f50 mm/shmem.c:1685
 writeout mm/vmscan.c:649 [inline]
 pageout mm/vmscan.c:698 [inline]
 shrink_folio_list+0x5951/0x7fd0 mm/vmscan.c:1418
 evict_folios+0x9aa3/0xc030 mm/vmscan.c:4711
 try_to_shrink_lruvec+0x1251/0x1750 mm/vmscan.c:4874
 shrink_one+0x4bd/0xbc0 mm/vmscan.c:4919
 shrink_many mm/vmscan.c:4982 [inline]
 lru_gen_shrink_node mm/vmscan.c:5060 [inline]
 shrink_node+0x4505/0x51a0 mm/vmscan.c:6047
 kswapd_shrink_node mm/vmscan.c:6901 [inline]
 balance_pgdat mm/vmscan.c:7084 [inline]
 kswapd+0x2c29/0x4e20 mm/vmscan.c:7354
 kthread+0xd5a/0xf00 kernel/kthread.c:463
 ret_from_fork+0x207/0x6f0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Uninit was stored to memory at:
 memcpy_from_iter lib/iov_iter.c:85 [inline]
 iterate_bvec include/linux/iov_iter.h:123 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:306 [inline]
 iterate_and_advance include/linux/iov_iter.h:330 [inline]
 __copy_from_iter lib/iov_iter.c:261 [inline]
 copy_folio_from_iter_atomic+0xea0/0x38b0 lib/iov_iter.c:491
 generic_perform_write+0x8b7/0x1050 mm/filemap.c:4332
 shmem_file_write_iter+0x2b7/0x2f0 mm/shmem.c:3513
 lo_rw_aio+0x1164/0x14a0 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1947 [inline]
 loop_process_work+0xf05/0x1ff0 drivers/block/loop.c:1982
 loop_workfn+0x3e/0x60 drivers/block/loop.c:2006
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xae7/0x1d60 kernel/workqueue.c:3340
 worker_thread+0x1741/0x1de0 kernel/workqueue.c:3421
 kthread+0xd5a/0xf00 kernel/kthread.c:463
 ret_from_fork+0x207/0x6f0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Uninit was created at:
 __alloc_frozen_pages_noprof+0x6df/0xf50 mm/page_alloc.c:5263
 __alloc_pages_noprof mm/page_alloc.c:5274 [inline]
 alloc_pages_bulk_noprof+0x11f6/0x19d0 mm/page_alloc.c:5194
 btrfs_alloc_page_array fs/btrfs/extent_io.c:677 [inline]
 alloc_eb_folio_array+0x15a/0x670 fs/btrfs/extent_io.c:701
 alloc_extent_buffer+0x884/0x3cf0 fs/btrfs/extent_io.c:3433
 btrfs_find_create_tree_block+0x44/0x60 fs/btrfs/disk-io.c:592
 btrfs_init_new_buffer fs/btrfs/extent-tree.c:5049 [inline]
 btrfs_alloc_tree_block+0x3fe/0x1bc0 fs/btrfs/extent-tree.c:5162
 btrfs_create_tree+0x22b/0xa40 fs/btrfs/disk-io.c:836
 btrfs_quota_enable+0x504/0x44f0 fs/btrfs/qgroup.c:1044
 btrfs_ioctl_quota_ctl+0x350/0x490 fs/btrfs/ioctl.c:3613
 btrfs_ioctl+0x9ad/0x1340 fs/btrfs/ioctl.c:5296
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0x23c/0x400 fs/ioctl.c:583
 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:583
 x64_sys_call+0x18a7/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 87 Comm: kswapd1 Tainted: G             L      syzkaller #0 PREEMPT(voluntary) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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