KMSAN: uninit-value in ext4_inode_journal_mode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    73d62e81 kmsan: random: prevent boot-time reports in _mix_..
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=152188c4d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=df698232b2ac45c9
dashboard link: https://syzkaller.appspot.com/bug?extid=b2ffafb709f9a29ec5b4
compiler:       Debian clang version 11.0.1-2
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2ffafb709f9a29ec5b4@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in ext4_inode_journal_mode+0x28b/0x4f0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/ext4_jbd2.c:16
CPU: 1 PID: 8577 Comm: syz-executor.0 Not tainted 5.10.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack syzkaller/managers/upstream-kmsan-gce-386/kernel/lib/dump_stack.c:77 [inline]
 dump_stack+0x21c/0x280 syzkaller/managers/upstream-kmsan-gce-386/kernel/lib/dump_stack.c:118
 kmsan_report+0xfb/0x1e0 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/kmsan/kmsan_report.c:118
 __msan_warning+0x5f/0xa0 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/kmsan/kmsan_instr.c:197
 ext4_inode_journal_mode+0x28b/0x4f0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/ext4_jbd2.c:16
 ext4_should_journal_data syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/ext4_jbd2.h:467 [inline]
 ext4_evict_inode+0x1bb/0x2b30 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/inode.c:201
 evict+0x4b5/0xec0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:578
 iput_final syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:1654 [inline]
 iput+0xb06/0xec0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:1680
 __ext4_new_inode+0x3dd2/0x9c70 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/ialloc.c:1354
 ext4_create+0x47e/0x960 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/namei.c:2619
 lookup_open syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3104 [inline]
 open_last_lookups syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3178 [inline]
 path_openat+0x2b71/0x6a30 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3366
 do_filp_open+0x2b8/0x710 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3396
 do_sys_openat2+0xa92/0x1150 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/open.c:1168
 do_sys_open syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/open.c:1184 [inline]
 __do_compat_sys_openat syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/open.c:1242 [inline]
 __se_compat_sys_openat+0x2ae/0x310 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/open.c:1240
 __ia32_compat_sys_openat+0x56/0x70 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/open.c:1240
 do_syscall_32_irqs_on syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x102/0x160 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7f79549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f55525fc EFLAGS: 00000296 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000200004c0
RDX: 0000000000000042 RSI: 0000000000000180 RDI: 0000000000000000
RBP: 0000000000000000 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 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/kmsan/kmsan.c:121
 kmsan_alloc_page+0xd3/0x1f0 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/kmsan/kmsan_shadow.c:274
 __alloc_pages_nodemask+0x827/0xf90 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/page_alloc.c:4989
 alloc_pages_current+0x7b6/0xb60 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/mempolicy.c:2271
 alloc_pages syzkaller/managers/upstream-kmsan-gce-386/kernel/./include/linux/gfp.h:547 [inline]
 alloc_slab_page syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:1630 [inline]
 allocate_slab+0x346/0x11a0 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:1773
 new_slab syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:1834 [inline]
 new_slab_objects syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2593 [inline]
 ___slab_alloc+0xd42/0x1930 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2756
 __slab_alloc syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2796 [inline]
 slab_alloc_node syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2871 [inline]
 slab_alloc syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2915 [inline]
 kmem_cache_alloc+0xb71/0x1040 syzkaller/managers/upstream-kmsan-gce-386/kernel/mm/slub.c:2920
 ext4_alloc_inode+0x5e/0x870 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/super.c:1294
 alloc_inode syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:234 [inline]
 new_inode_pseudo+0xa7/0x580 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:930
 new_inode+0x5a/0x3d0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/inode.c:959
 __ext4_new_inode+0x3a0/0x9c70 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/ialloc.c:956
 ext4_symlink+0x8a4/0x19a0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/ext4/namei.c:3336
 vfs_symlink+0x6c4/0x8f0 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3960
 do_symlinkat+0x389/0x930 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:3987
 __do_sys_symlink syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:4006 [inline]
 __se_sys_symlink+0x74/0x90 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:4004
 __ia32_sys_symlink+0x3e/0x60 syzkaller/managers/upstream-kmsan-gce-386/kernel/fs/namei.c:4004
 do_syscall_32_irqs_on syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:80 [inline]
 __do_fast_syscall_32+0x102/0x160 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:139
 do_fast_syscall_32+0x6a/0xc0 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:162
 do_SYSENTER_32+0x73/0x90 syzkaller/managers/upstream-kmsan-gce-386/kernel/arch/x86/entry/common.c:205
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
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