=====================================================
BUG: KMSAN: uninit-value in LZ4_decompress_generic lib/lz4/lz4_decompress.c:148 [inline]
BUG: KMSAN: uninit-value in LZ4_decompress_safe_partial+0x825/0x1e50 lib/lz4/lz4_decompress.c:473
 LZ4_decompress_generic lib/lz4/lz4_decompress.c:148 [inline]
 LZ4_decompress_safe_partial+0x825/0x1e50 lib/lz4/lz4_decompress.c:473
 __bio_uncompress+0x503/0xa30 fs/bcachefs/compress.c:166
 bch2_bio_uncompress+0x4d9/0x800 fs/bcachefs/compress.c:283
 __bch2_read_endio+0x1b17/0x3070 fs/bcachefs/io_read.c:617
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
 __alloc_pages_noprof+0x9a7/0xe00 mm/page_alloc.c:4774
 alloc_pages_mpol_noprof+0x299/0x990 mm/mempolicy.c:2265
 alloc_pages_noprof+0x1bf/0x1e0 mm/mempolicy.c:2344
 __bio_alloc_page_pool fs/bcachefs/io_write.c:113 [inline]
 bch2_bio_alloc_pages_pool+0xc2/0x2d0 fs/bcachefs/io_write.c:134
 __bch2_read_extent+0x33b8/0x6a50 fs/bcachefs/io_read.c:988
 bch2_read_extent fs/bcachefs/io_read.h:120 [inline]
 bchfs_read+0x2f5e/0x3660 fs/bcachefs/fs-io-buffered.c:217
 bch2_read_single_folio+0x646/0x890 fs/bcachefs/fs-io-buffered.c:316
 __bch2_truncate_folio+0x1b4c/0x3060 fs/bcachefs/fs-io.c:285
 bch2_truncate_folio fs/bcachefs/fs-io.c:347 [inline]
 bchfs_truncate+0x8cb/0x1490 fs/bcachefs/fs-io.c:437
 bch2_setattr+0x29f/0x2f0 fs/bcachefs/fs.c:1163
 notify_change+0x1a8e/0x1b80 fs/attr.c:552
 do_truncate+0x22a/0x2b0 fs/open.c:65
 vfs_truncate+0x5d4/0x680 fs/open.c:111
 do_sys_truncate+0x104/0x240 fs/open.c:134
 __do_sys_truncate fs/open.c:146 [inline]
 __se_sys_truncate fs/open.c:144 [inline]
 __x64_sys_truncate+0x6c/0xa0 fs/open.c:144
 x64_sys_call+0x2e19/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:77
 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: 1 UID: 0 PID: 4905 Comm: kworker/u8:25 Tainted: G        W          6.12.0-syzkaller-11930-g0e287d31b62b #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_unbound __bch2_read_endio
=====================================================