=====================================================
BUG: KMSAN: uninit-value in ext4_ext_binsearch fs/ext4/extents.c:834 [inline]
BUG: KMSAN: uninit-value in ext4_find_extent+0x1781/0x1940 fs/ext4/extents.c:956
 ext4_ext_binsearch fs/ext4/extents.c:834 [inline]
 ext4_find_extent+0x1781/0x1940 fs/ext4/extents.c:956
 ext4_ext_map_blocks+0x17c/0x9840 fs/ext4/extents.c:4261
 ext4_map_create_blocks+0x234/0xc60 fs/ext4/inode.c:616
 ext4_map_blocks+0xc9c/0x17f0 fs/ext4/inode.c:809
 ext4_convert_unwritten_extents+0x404/0xa60 fs/ext4/extents.c:5029
 ext4_convert_unwritten_io_end_vec+0x1d8/0x400 fs/ext4/extents.c:5069
 ext4_end_io_end+0x11b/0x6b0 fs/ext4/page-io.c:200
 ext4_do_flush_completed_IO fs/ext4/page-io.c:291 [inline]
 ext4_end_io_rsv_work+0x33b/0x6d0 fs/ext4/page-io.c:306
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb21/0x1e30 kernel/workqueue.c:3358
 worker_thread+0xede/0x1580 kernel/workqueue.c:3439
 kthread+0x53f/0x600 kernel/kthread.c:436
 ret_from_fork+0x20f/0x910 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 __alloc_frozen_pages_noprof+0x6f7/0x1020 mm/page_alloc.c:5273
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof mm/mempolicy.c:2575 [inline]
 folio_alloc_noprof+0x108/0x360 mm/mempolicy.c:2585
 filemap_alloc_folio_noprof+0xd9/0x480 mm/filemap.c:1013
 __filemap_get_folio_mpol+0xb43/0x1960 mm/filemap.c:2011
 __filemap_get_folio include/linux/pagemap.h:774 [inline]
 grow_dev_folio fs/buffer.c:1047 [inline]
 grow_buffers fs/buffer.c:1113 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x2c9/0xb30 fs/buffer.c:1458
 sb_getblk_gfp include/linux/buffer_head.h:392 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1335 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1434 [inline]
 ext4_ext_insert_extent+0x27e8/0x86b0 fs/ext4/extents.c:2120
 ext4_ext_map_blocks+0x3f85/0x9840 fs/ext4/extents.c:4457
 ext4_map_create_blocks+0x234/0xc60 fs/ext4/inode.c:616
 ext4_map_blocks+0xc9c/0x17f0 fs/ext4/inode.c:809
 _ext4_get_block+0x1f8/0x790 fs/ext4/inode.c:909
 ext4_get_block_unwritten+0x48/0x1b0 fs/ext4/inode.c:942
 ext4_block_write_begin+0x119b/0x2c00 fs/ext4/inode.c:1196
 ext4_write_begin+0xf79/0x2db0 fs/ext4/inode.c:-1
 ext4_da_write_begin+0x75e/0x1490 fs/ext4/inode.c:3123
 generic_perform_write+0x364/0x1050 mm/filemap.c:4319
 ext4_buffered_write_iter+0x61a/0xce0 fs/ext4/file.c:300
 ext4_file_write_iter+0x24b4/0x3d80 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0xbe1/0x15c0 fs/read_write.c:688
 ksys_pwrite64 fs/read_write.c:795 [inline]
 __do_sys_pwrite64 fs/read_write.c:803 [inline]
 __se_sys_pwrite64 fs/read_write.c:800 [inline]
 __x64_sys_pwrite64+0x2ab/0x3b0 fs/read_write.c:800
 x64_sys_call+0xbef/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:19
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 56 Comm: kworker/u8:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
=====================================================