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BUG: KMSAN: uninit-value in btrfs_clean_tree_block+0x293/0x330 fs/btrfs/disk-io.c:1066
CPU: 1 PID: 8840 Comm: syz-executor.1 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 btrfs_clean_tree_block+0x293/0x330 fs/btrfs/disk-io.c:1066
 btrfs_init_new_buffer fs/btrfs/extent-tree.c:4526 [inline]
 btrfs_alloc_tree_block+0x93d/0x1f40 fs/btrfs/extent-tree.c:4603
 alloc_tree_block_no_bg_flush fs/btrfs/ctree.c:987 [inline]
 __btrfs_cow_block+0xb17/0x23f0 fs/btrfs/ctree.c:1042
 btrfs_cow_block+0xa15/0xce0 fs/btrfs/ctree.c:1483
 commit_cowonly_roots+0x1c0/0x1610 fs/btrfs/transaction.c:1181
 btrfs_commit_transaction+0x32ff/0x56b0 fs/btrfs/transaction.c:2268
 btrfs_sync_fs+0x63c/0x6c0 fs/btrfs/super.c:1308
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem+0x2d4/0x440 fs/sync.c:67
 generic_shutdown_super+0xc7/0x650 fs/super.c:448
 kill_anon_super+0x6c/0xb0 fs/super.c:1108
 btrfs_kill_super+0x61/0x90 fs/btrfs/super.c:2181
 deactivate_locked_super+0x10d/0x1e0 fs/super.c:335
 deactivate_super+0x1b7/0x1d0 fs/super.c:366
 cleanup_mnt+0x796/0x880 fs/namespace.c:1118
 __cleanup_mnt+0x3b/0x50 fs/namespace.c:1125
 task_work_run+0x1f2/0x2e0 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:240 [inline]
 __prepare_exit_to_usermode+0x45b/0x560 arch/x86/entry/common.c:270
 __syscall_return_slowpath arch/x86/entry/common.c:353 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:433 [inline]
 __do_fast_syscall_32+0x346/0x480 arch/x86/entry/common.c:477
 do_fast_syscall_32+0x6b/0xd0 arch/x86/entry/common.c:505
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:554
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7f05549
Code: Bad RIP value.
RSP: 002b:00000000ffab3e6c EFLAGS: 00000296 ORIG_RAX: 0000000000000034
RAX: 0000000000000000 RBX: 00000000ffab3efc RCX: 0000000000000002
RDX: 0000000009c34228 RSI: 0000000009c34288 RDI: 00000000080d837e
RBP: 00000000ffab3efc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
 kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:293
 __alloc_pages_nodemask+0xdf0/0x1030 mm/page_alloc.c:4889
 alloc_pages_current+0x685/0xb50 mm/mempolicy.c:2292
 alloc_pages include/linux/gfp.h:545 [inline]
 __page_cache_alloc+0xc8/0x310 mm/filemap.c:956
 pagecache_get_page+0xe76/0x1b70 mm/filemap.c:1642
 find_or_create_page include/linux/pagemap.h:348 [inline]
 alloc_extent_buffer+0x7c5/0x2820 fs/btrfs/extent_io.c:5218
 btrfs_find_create_tree_block+0x68/0x80 fs/btrfs/disk-io.c:1031
 btrfs_init_new_buffer fs/btrfs/extent-tree.c:4507 [inline]
 btrfs_alloc_tree_block+0x4f6/0x1f40 fs/btrfs/extent-tree.c:4603
 alloc_tree_block_no_bg_flush fs/btrfs/ctree.c:987 [inline]
 __btrfs_cow_block+0xb17/0x23f0 fs/btrfs/ctree.c:1042
 btrfs_cow_block+0xa15/0xce0 fs/btrfs/ctree.c:1483
 commit_cowonly_roots+0x1c0/0x1610 fs/btrfs/transaction.c:1181
 btrfs_commit_transaction+0x32ff/0x56b0 fs/btrfs/transaction.c:2268
 btrfs_sync_fs+0x63c/0x6c0 fs/btrfs/super.c:1308
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem+0x2d4/0x440 fs/sync.c:67
 generic_shutdown_super+0xc7/0x650 fs/super.c:448
 kill_anon_super+0x6c/0xb0 fs/super.c:1108
 btrfs_kill_super+0x61/0x90 fs/btrfs/super.c:2181
 deactivate_locked_super+0x10d/0x1e0 fs/super.c:335
 deactivate_super+0x1b7/0x1d0 fs/super.c:366
 cleanup_mnt+0x796/0x880 fs/namespace.c:1118
 __cleanup_mnt+0x3b/0x50 fs/namespace.c:1125
 task_work_run+0x1f2/0x2e0 kernel/task_work.c:135
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:240 [inline]
 __prepare_exit_to_usermode+0x45b/0x560 arch/x86/entry/common.c:270
 __syscall_return_slowpath arch/x86/entry/common.c:353 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:433 [inline]
 __do_fast_syscall_32+0x346/0x480 arch/x86/entry/common.c:477
 do_fast_syscall_32+0x6b/0xd0 arch/x86/entry/common.c:505
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:554
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
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