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BUG: KMSAN: uninit-value in iov_iter_alignment_iovec+0x19e/0x470 lib/iov_iter.c:894
 iov_iter_alignment_iovec+0x19e/0x470 lib/iov_iter.c:894
 iov_iter_alignment+0x174/0x2d0 lib/iov_iter.c:939
 check_direct_IO fs/btrfs/direct-io.c:787 [inline]
 check_direct_read fs/btrfs/direct-io.c:997 [inline]
 btrfs_direct_read+0x204/0xa20 fs/btrfs/direct-io.c:1026
 btrfs_file_read_iter+0xce/0x310 fs/btrfs/file.c:3657
 io_iter_do_read io_uring/rw.c:824 [inline]
 __io_read+0xbe6/0x2490 io_uring/rw.c:937
 io_read+0x3e/0x100 io_uring/rw.c:1016
 __io_issue_sqe io_uring/io_uring.c:1734 [inline]
 io_issue_sqe+0x392/0x1fa0 io_uring/io_uring.c:1753
 io_queue_sqe io_uring/io_uring.c:1969 [inline]
 io_submit_sqe io_uring/io_uring.c:2225 [inline]
 io_submit_sqes+0x11a4/0x2d80 io_uring/io_uring.c:2342
 __do_sys_io_uring_enter io_uring/io_uring.c:3402 [inline]
 __se_sys_io_uring_enter+0x3b7/0x4c40 io_uring/io_uring.c:3336
 __x64_sys_io_uring_enter+0x114/0x1a0 io_uring/io_uring.c:3336
 x64_sys_call+0x317f/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 __alloc_frozen_pages_noprof+0x689/0xf00 mm/page_alloc.c:4993
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2301
 alloc_frozen_pages_noprof+0xf7/0x200 mm/mempolicy.c:2372
 alloc_slab_page mm/slub.c:2468 [inline]
 allocate_slab+0x24d/0x1210 mm/slub.c:2632
 new_slab mm/slub.c:2686 [inline]
 ___slab_alloc+0xfec/0x3480 mm/slub.c:3872
 __slab_alloc mm/slub.c:3962 [inline]
 __slab_alloc_node mm/slub.c:4037 [inline]
 slab_alloc_node mm/slub.c:4198 [inline]
 __kmalloc_cache_noprof+0x8ff/0xed0 mm/slub.c:4367
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 set_kthread_struct+0xee/0x530 kernel/kthread.c:126
 copy_process+0x18d1/0x5d10 kernel/fork.c:2357
 kernel_clone+0x416/0x1070 kernel/fork.c:2844
 kernel_thread+0x13f/0x170 kernel/fork.c:2906
 create_kthread kernel/kthread.c:487 [inline]
 kthreadd+0x55d/0x9f0 kernel/kthread.c:847
 ret_from_fork+0x6e/0x90 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 1 UID: 0 PID: 6080 Comm: syz.1.24 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8 #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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