Hello, syzbot found the following issue on: HEAD commit: 610a9b8f49fb Linux 6.7-rc8 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=110b4555e80000 kernel config: https://syzkaller.appspot.com/x/.config?x=e51fe20c3e51ba7f dashboard link: https://syzkaller.appspot.com/bug?extid=3ce5dea5b1539ff36769 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 userspace arch: i386 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/daced691c987/disk-610a9b8f.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/5e37367a7d1e/vmlinux-610a9b8f.xz kernel image: https://storage.googleapis.com/syzbot-assets/013b65c960ab/bzImage-610a9b8f.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3ce5dea5b1539ff36769@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in memcmp lib/string.c:681 [inline] BUG: KMSAN: uninit-value in bcmp+0xc3/0x1c0 lib/string.c:713 memcmp lib/string.c:681 [inline] bcmp+0xc3/0x1c0 lib/string.c:713 sample_repeated_patterns fs/btrfs/compression.c:1298 [inline] btrfs_compress_heuristic+0x926/0x31f0 fs/btrfs/compression.c:1380 inode_need_compress fs/btrfs/inode.c:804 [inline] btrfs_run_delalloc_range+0x156c/0x16c0 fs/btrfs/inode.c:2272 writepage_delalloc+0x244/0x6b0 fs/btrfs/extent_io.c:1189 __extent_writepage fs/btrfs/extent_io.c:1440 [inline] extent_write_cache_pages fs/btrfs/extent_io.c:2108 [inline] extent_writepages+0x1d22/0x3f20 fs/btrfs/extent_io.c:2230 btrfs_writepages+0x35/0x40 fs/btrfs/inode.c:7836 do_writepages+0x426/0x870 mm/page-writeback.c:2553 filemap_fdatawrite_wbc+0x1d8/0x270 mm/filemap.c:387 start_delalloc_inodes+0x91d/0x1560 fs/btrfs/inode.c:9284 btrfs_start_delalloc_roots+0x874/0xe80 fs/btrfs/inode.c:9361 shrink_delalloc fs/btrfs/space-info.c:649 [inline] flush_space+0xbd4/0x16c0 fs/btrfs/space-info.c:759 btrfs_async_reclaim_metadata_space+0x76d/0x9c0 fs/btrfs/space-info.c:1089 process_one_work kernel/workqueue.c:2627 [inline] process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2700 worker_thread+0xf45/0x1490 kernel/workqueue.c:2781 kthread+0x3ed/0x540 kernel/kthread.c:388 ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 Uninit was stored to memory at: heuristic_collect_sample fs/btrfs/compression.c:1338 [inline] btrfs_compress_heuristic+0x303/0x31f0 fs/btrfs/compression.c:1378 inode_need_compress fs/btrfs/inode.c:804 [inline] btrfs_run_delalloc_range+0x156c/0x16c0 fs/btrfs/inode.c:2272 writepage_delalloc+0x244/0x6b0 fs/btrfs/extent_io.c:1189 __extent_writepage fs/btrfs/extent_io.c:1440 [inline] extent_write_cache_pages fs/btrfs/extent_io.c:2108 [inline] extent_writepages+0x1d22/0x3f20 fs/btrfs/extent_io.c:2230 btrfs_writepages+0x35/0x40 fs/btrfs/inode.c:7836 do_writepages+0x426/0x870 mm/page-writeback.c:2553 filemap_fdatawrite_wbc+0x1d8/0x270 mm/filemap.c:387 start_delalloc_inodes+0x91d/0x1560 fs/btrfs/inode.c:9284 btrfs_start_delalloc_roots+0x874/0xe80 fs/btrfs/inode.c:9361 shrink_delalloc fs/btrfs/space-info.c:649 [inline] flush_space+0xbd4/0x16c0 fs/btrfs/space-info.c:759 btrfs_async_reclaim_metadata_space+0x76d/0x9c0 fs/btrfs/space-info.c:1089 process_one_work kernel/workqueue.c:2627 [inline] process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2700 worker_thread+0xf45/0x1490 kernel/workqueue.c:2781 kthread+0x3ed/0x540 kernel/kthread.c:388 ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 Uninit was created at: __alloc_pages+0x9a4/0xe00 mm/page_alloc.c:4591 alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133 alloc_pages mm/mempolicy.c:2204 [inline] folio_alloc+0x1da/0x380 mm/mempolicy.c:2211 filemap_alloc_folio+0xa5/0x430 mm/filemap.c:974 __filemap_get_folio+0xa5a/0x1760 mm/filemap.c:1918 pagecache_get_page+0x4a/0x1a0 mm/folio-compat.c:99 prepare_pages+0x1f2/0x1050 fs/btrfs/file.c:922 btrfs_buffered_write+0xe48/0x2be0 fs/btrfs/file.c:1316 btrfs_do_write_iter+0x370/0x2300 fs/btrfs/file.c:1687 btrfs_file_write_iter+0x38/0x40 fs/btrfs/file.c:1704 __kernel_write_iter+0x329/0x930 fs/read_write.c:517 dump_emit_page fs/coredump.c:888 [inline] dump_user_range+0x593/0xcd0 fs/coredump.c:915 elf_core_dump+0x59e8/0x5c60 fs/binfmt_elf.c:2077 do_coredump+0x32c9/0x4920 fs/coredump.c:764 get_signal+0x2185/0x2d10 kernel/signal.c:2890 arch_do_signal_or_restart+0x53/0xca0 arch/x86/kernel/signal.c:309 exit_to_user_mode_loop+0xe8/0x320 kernel/entry/common.c:168 exit_to_user_mode_prepare+0x163/0x220 kernel/entry/common.c:204 irqentry_exit_to_user_mode+0xd/0x30 kernel/entry/common.c:309 irqentry_exit+0x16/0x40 kernel/entry/common.c:412 exc_page_fault+0x246/0x6f0 arch/x86/mm/fault.c:1564 asm_exc_page_fault+0x2b/0x30 arch/x86/include/asm/idtentry.h:570 CPU: 1 PID: 56 Comm: kworker/u4:4 Not tainted 6.7.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Workqueue: events_unbound btrfs_async_reclaim_metadata_space ===================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
