=====================================================
BUG: KMSAN: uninit-value in iov_iter_alignment_iovec+0x19e/0x470 lib/iov_iter.c:891
 iov_iter_alignment_iovec+0x19e/0x470 lib/iov_iter.c:891
 iov_iter_alignment+0x174/0x2d0 lib/iov_iter.c:936
 check_direct_IO fs/btrfs/direct-io.c:786 [inline]
 check_direct_read fs/btrfs/direct-io.c:996 [inline]
 btrfs_direct_read+0x204/0xa20 fs/btrfs/direct-io.c:1025
 btrfs_file_read_iter+0xce/0x310 fs/btrfs/file.c:3753
 io_iter_do_read io_uring/rw.c:828 [inline]
 __io_read+0xbe9/0x24a0 io_uring/rw.c:941
 io_read+0x3e/0x100 io_uring/rw.c:1020
 __io_issue_sqe+0x2b8/0x790 io_uring/io_uring.c:1730
 io_issue_sqe+0xae/0x19b0 io_uring/io_uring.c:1753
 io_queue_sqe io_uring/io_uring.c:1960 [inline]
 io_submit_sqe io_uring/io_uring.c:2216 [inline]
 io_submit_sqes+0x120f/0x2d60 io_uring/io_uring.c:2329
 __do_sys_io_uring_enter io_uring/io_uring.c:3396 [inline]
 __se_sys_io_uring_enter+0x3b7/0x4c40 io_uring/io_uring.c:3330
 __x64_sys_io_uring_enter+0x114/0x1a0 io_uring/io_uring.c:3330
 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+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4153 [inline]
 slab_alloc_node mm/slub.c:4196 [inline]
 __do_kmalloc_node mm/slub.c:4326 [inline]
 __kmalloc_noprof+0x95f/0x1310 mm/slub.c:4339
 kmalloc_noprof include/linux/slab.h:909 [inline]
 io_cache_alloc_new+0x55/0x140 io_uring/alloc_cache.c:40
 io_cache_alloc io_uring/alloc_cache.h:59 [inline]
 io_uring_alloc_async_data io_uring/io_uring.h:246 [inline]
 io_rw_alloc_async io_uring/rw.c:202 [inline]
 __io_prep_rw+0x1cd/0x12e0 io_uring/rw.c:261
 io_prep_rw io_uring/rw.c:320 [inline]
 io_prep_rwv+0x43/0x570 io_uring/rw.c:342
 io_prep_readv+0x38/0x50 io_uring/rw.c:357
 io_init_req io_uring/io_uring.c:2131 [inline]
 io_submit_sqe io_uring/io_uring.c:2178 [inline]
 io_submit_sqes+0x10e7/0x2d60 io_uring/io_uring.c:2329
 __do_sys_io_uring_enter io_uring/io_uring.c:3396 [inline]
 __se_sys_io_uring_enter+0x3b7/0x4c40 io_uring/io_uring.c:3330
 __x64_sys_io_uring_enter+0x114/0x1a0 io_uring/io_uring.c:3330
 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+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 6714 Comm: syz.0.17 Not tainted 6.15.0-syzkaller-11796-g5abc7438f1e9 #0 PREEMPT(undef) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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