=====================================================
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+0x62a/0xde0 fs/bcachefs/compress.c:200
 bch2_bio_uncompress+0x523/0x880 fs/bcachefs/compress.c:323
 __bch2_read_endio+0x18de/0x2340 fs/bcachefs/io_read.c:790
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xb97/0x1d90 kernel/workqueue.c:3319
 worker_thread+0xedf/0x1590 kernel/workqueue.c:3400
 kthread+0xd59/0xf00 kernel/kthread.c:464
 ret_from_fork+0x6e/0x90 arch/x86/kernel/process.c:153
 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:4993
 alloc_pages_mpol+0x328/0x860 mm/mempolicy.c:2301
 alloc_frozen_pages_noprof mm/mempolicy.c:2372 [inline]
 alloc_pages_noprof+0x102/0x280 mm/mempolicy.c:2392
 __bio_alloc_page_pool fs/bcachefs/io_write.c:119 [inline]
 bch2_bio_alloc_pages_pool+0x8f/0x230 fs/bcachefs/io_write.c:140
 __bch2_read_extent+0x3451/0x60a0 fs/bcachefs/io_read.c:1096
 bch2_read_extent fs/bcachefs/io_read.h:140 [inline]
 bchfs_read+0x3afd/0x4690 fs/bcachefs/fs-io-buffered.c:226
 bch2_read_single_folio+0x6fe/0xb20 fs/bcachefs/fs-io-buffered.c:360
 __bch2_truncate_folio+0x1f5b/0x36d0 fs/bcachefs/fs-io.c:314
 bch2_truncate_folio fs/bcachefs/fs-io.c:376 [inline]
 bchfs_truncate+0x8c9/0x1410 fs/bcachefs/fs-io.c:466
 bch2_setattr+0x298/0x300 fs/bcachefs/fs.c:1218
 notify_change+0x1990/0x1aa0 fs/attr.c:552
 do_truncate+0x224/0x2a0 fs/open.c:65
 vfs_truncate+0x921/0x9d0 fs/open.c:115
 do_sys_truncate+0x103/0x240 fs/open.c:138
 __do_sys_truncate fs/open.c:150 [inline]
 __se_sys_truncate fs/open.c:148 [inline]
 __x64_sys_truncate+0x74/0xb0 fs/open.c:148
 x64_sys_call+0x321f/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:77
 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

CPU: 0 UID: 0 PID: 35 Comm: kworker/u8:2 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
Workqueue: events_unbound __bch2_read_endio
=====================================================