=====================================================
BUG: KMSAN: uninit-value in iov_iter_alignment_iovec+0x1a8/0x470 lib/iov_iter.c:894
 iov_iter_alignment_iovec+0x1a8/0x470 lib/iov_iter.c:894
 iov_iter_alignment+0x1ac/0x2d0 lib/iov_iter.c:939
 check_direct_IO fs/btrfs/direct-io.c:786 [inline]
 check_direct_read fs/btrfs/direct-io.c:980 [inline]
 btrfs_direct_read+0x20b/0x9c0 fs/btrfs/direct-io.c:1009
 btrfs_file_read_iter+0xe3/0x2d0 fs/btrfs/file.c:3645
 io_iter_do_read io_uring/rw.c:783 [inline]
 __io_read+0x8ea/0x2130 io_uring/rw.c:892
 io_read+0x3e/0xf0 io_uring/rw.c:971
 io_issue_sqe+0x436/0x1fb0 io_uring/io_uring.c:1737
 io_queue_sqe io_uring/io_uring.c:1947 [inline]
 io_submit_sqe io_uring/io_uring.c:2204 [inline]
 io_submit_sqes+0x11c3/0x2ff0 io_uring/io_uring.c:2321
 __do_sys_io_uring_enter io_uring/io_uring.c:3372 [inline]
 __se_sys_io_uring_enter+0x41d/0x4da0 io_uring/io_uring.c:3307
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3307
 x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4121 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 __do_kmalloc_node mm/slub.c:4293 [inline]
 __kmalloc_noprof+0x923/0x1230 mm/slub.c:4306
 kmalloc_noprof include/linux/slab.h:905 [inline]
 io_cache_alloc_new+0x54/0x140 io_uring/alloc_cache.c:40
 io_cache_alloc io_uring/alloc_cache.h:68 [inline]
 io_uring_alloc_async_data io_uring/io_uring.h:232 [inline]
 io_rw_alloc_async io_uring/rw.c:206 [inline]
 io_prep_rw_setup io_uring/rw.c:219 [inline]
 io_prep_rw+0x90e/0x1380 io_uring/rw.c:303
 io_prep_rwv+0xb3/0x510 io_uring/rw.c:338
 io_prep_readv+0x37/0x50 io_uring/rw.c:353
 io_init_req io_uring/io_uring.c:2119 [inline]
 io_submit_sqe io_uring/io_uring.c:2166 [inline]
 io_submit_sqes+0x1089/0x2ff0 io_uring/io_uring.c:2321
 __do_sys_io_uring_enter io_uring/io_uring.c:3372 [inline]
 __se_sys_io_uring_enter+0x41d/0x4da0 io_uring/io_uring.c:3307
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3307
 x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 11602 Comm: syz.4.1209 Not tainted 6.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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