syzbot


KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks (3)

Status: closed as invalid on 2022/05/13 11:20
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 205d, last: 205d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks (2) 150 350d 549d 0/24 auto-closed as invalid on 2022/01/21 20:42
upstream KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks 184 669d 821d 0/24 auto-closed as invalid on 2021/03/09 10:48

Sample crash report:
==================================================================
BUG: KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks

read-write to 0xffff888102814b54 of 4 bytes by task 1403 on cpu 1:
 mb_free_blocks+0x135/0xcb0 fs/ext4/mballoc.c:1802
 ext4_free_data_in_buddy+0x27e/0x580 fs/ext4/mballoc.c:3662
 ext4_process_freed_data+0x24b/0x400 fs/ext4/mballoc.c:3713
 ext4_journal_commit_callback+0x83/0x1a0 fs/ext4/super.c:467
 jbd2_journal_commit_transaction+0x28ac/0x3180 fs/jbd2/commit.c:1160
 kjournald2+0x253/0x460 fs/jbd2/journal.c:213
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff888102814b54 of 4 bytes by task 1827 on cpu 0:
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2504 [inline]
 ext4_mb_regular_allocator+0xac9/0x1ff0 fs/ext4/mballoc.c:2747
 ext4_mb_new_blocks+0x839/0xfd0 fs/ext4/mballoc.c:5616
 ext4_ext_map_blocks+0xd55/0x1bb0 fs/ext4/extents.c:4281
 ext4_map_blocks+0x75b/0xfc0 fs/ext4/inode.c:636
 ext4_getblk+0xcb/0x410 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+0x216/0x320 fs/namei.c:3931
 do_mkdirat+0x105/0x280 fs/namei.c:3957
 __do_sys_mkdirat fs/namei.c:3972 [inline]
 __se_sys_mkdirat fs/namei.c:3970 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:3970
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000007e7 -> 0x000007f4

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1827 Comm: syz-executor.4 Not tainted 5.18.0-rc6-syzkaller-00009-gfeb9c5e19e91 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/05/11 18:27 upstream feb9c5e19e91 beb0b407 .config log report info KCSAN: data-race in ext4_mb_regular_allocator / mb_free_blocks
* Struck through repros no longer work on HEAD.