=====================================================
BUG: KMSAN: uninit-value in LZ4_decompress_generic lib/lz4/lz4_decompress.c:147 [inline]
BUG: KMSAN: uninit-value in LZ4_decompress_safe_partial+0x94a/0x2190 lib/lz4/lz4_decompress.c:472
 LZ4_decompress_generic lib/lz4/lz4_decompress.c:147 [inline]
 LZ4_decompress_safe_partial+0x94a/0x2190 lib/lz4/lz4_decompress.c:472
 __bio_uncompress+0x627/0x1490 fs/bcachefs/compress.c:200
 bch2_bio_uncompress+0x507/0x9b0 fs/bcachefs/compress.c:323
 __bch2_read_endio+0x17e4/0x2240 fs/bcachefs/io_read.c:871
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xb8e/0x1d80 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd59/0xf00 kernel/kthread.c:463
 ret_from_fork+0x1e3/0x310 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
 __alloc_frozen_pages_noprof+0x689/0xf00 mm/page_alloc.c:5171
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0x102/0x280 mm/mempolicy.c:2507
 __bio_alloc_page_pool fs/bcachefs/io_write.c:121 [inline]
 bch2_bio_alloc_pages_pool+0x8f/0x230 fs/bcachefs/io_write.c:142
 __bch2_read_extent+0x334e/0x6220 fs/bcachefs/io_read.c:1193
 bch2_read_extent fs/bcachefs/io_read.h:147 [inline]
 bchfs_read+0x3ccb/0x4800 fs/bcachefs/fs-io-buffered.c:226
 bch2_read_single_folio+0x6fe/0xb20 fs/bcachefs/fs-io-buffered.c:360
 __bch2_truncate_folio+0x1f5c/0x3370 fs/bcachefs/fs-io.c:331
 bch2_truncate_folio fs/bcachefs/fs-io.c:393 [inline]
 bchfs_truncate+0x8c9/0x1550 fs/bcachefs/fs-io.c:483
 bch2_setattr+0x298/0x300 fs/bcachefs/fs.c:1241
 notify_change+0x1993/0x1aa0 fs/attr.c:552
 do_truncate+0x28f/0x310 fs/open.c:68
 vfs_truncate+0x921/0x9d0 fs/open.c:118
 do_sys_truncate+0x103/0x240 fs/open.c:141
 __do_sys_truncate fs/open.c:153 [inline]
 __se_sys_truncate fs/open.c:151 [inline]
 __x64_sys_truncate+0x74/0xb0 fs/open.c:151
 x64_sys_call+0x1f47/0x3e20 arch/x86/include/generated/asm/syscalls_64.h:77
 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: 1559 Comm: kworker/u8:4 Tainted: G        W           syzkaller #0 PREEMPT(none) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events_unbound __bch2_read_endio
=====================================================