KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d42e9818258 Merge tag 'gpio-fixes-for-v5.15-rc3' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e1bda0b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=11d01ee331121c57
dashboard link: https://syzkaller.appspot.com/bug?extid=43585170234428c94320
compiler: Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

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+435851...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

write to 0xffff8881010f1794 of 4 bytes by task 12688 on cpu 1:
mb_free_blocks+0x156/0xb40 fs/ext4/mballoc.c:1802
ext4_mb_release_inode_pa+0x301/0x570 fs/ext4/mballoc.c:4766
ext4_discard_preallocations+0x7c6/0xb60 fs/ext4/mballoc.c:5030
ext4_release_file+0x105/0x1d0 fs/ext4/file.c:149
__fput+0x295/0x520 fs/file_table.c:280
____fput+0x11/0x20 fs/file_table.c:313
task_work_run+0xae/0x130 kernel/task_work.c:164
exit_task_work include/linux/task_work.h:32 [inline]
do_exit+0x464/0x14a0 kernel/exit.c:825
do_group_exit+0xce/0x1a0 kernel/exit.c:922
get_signal+0xf93/0x15d0 kernel/signal.c:2868
arch_do_signal_or_restart+0x8c/0x280 arch/x86/kernel/signal.c:865
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:300
do_syscall_64+0x50/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881010f1794 of 4 bytes by task 1122 on cpu 0:
ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:839 [inline]
ext4_mb_rb_insert fs/ext4/mballoc.c:815 [inline]
mb_update_avg_fragment_size+0x184/0x260 fs/ext4/mballoc.c:863
mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1998
ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2019
ext4_mb_measure_extent fs/ext4/mballoc.c:2135 [inline]
ext4_mb_complex_scan_group+0x359/0x880 fs/ext4/mballoc.c:2365
ext4_mb_regular_allocator+0x1a32/0x2530 fs/ext4/mballoc.c:2778
ext4_mb_new_blocks+0x792/0x1fc0 fs/ext4/mballoc.c:5586
ext4_ext_map_blocks+0x15ed/0x1ff0 fs/ext4/extents.c:4250
ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
ext4_getblk+0xc6/0x3e0 fs/ext4/inode.c:847
ext4_bread+0x28/0x100 fs/ext4/inode.c:900
ext4_append+0xd1/0x1c0 fs/ext4/namei.c:67
ext4_init_new_dir+0x177/0x500 fs/ext4/namei.c:2893
ext4_mkdir+0x329/0x760 fs/ext4/namei.c:2939
vfs_mkdir+0x2c3/0x3e0 fs/namei.c:3885
do_mkdirat+0x12e/0x2c0 fs/namei.c:3911
__do_sys_mkdir fs/namei.c:3931 [inline]
__se_sys_mkdir fs/namei.c:3929 [inline]
__x64_sys_mkdir+0x40/0x50 fs/namei.c:3929
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00006ddf -> 0x00006e1b

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1122 Comm: syz-executor.5 Not tainted 5.15.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.