syzbot


KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order (2)

Status: auto-closed as invalid on 2021/10/07 17:10
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 476d, last: 459d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order 1 517d 517d 0/24 auto-closed as invalid on 2021/08/10 11:15

Sample crash report:
==================================================================
BUG: KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order

write to 0xffff888101cdb01c of 4 bytes by task 7570 on cpu 0:
 mb_set_largest_free_order+0x159/0x330 fs/ext4/mballoc.c:1084
 mb_mark_used+0xac0/0xc50 fs/ext4/mballoc.c:1992
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2015
 ext4_mb_try_best_found+0x234/0x3d0 fs/ext4/mballoc.c:2181
 ext4_mb_regular_allocator+0x22bd/0x2520 fs/ext4/mballoc.c:2779
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5515
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4713
 vfs_fallocate+0x459/0x6a0 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101cdb01c of 4 bytes by task 7573 on cpu 1:
 ext4_mb_good_group+0x30f/0x370 fs/ext4/mballoc.c:2452
 ext4_mb_good_group_nolock fs/ext4/mballoc.c:2529 [inline]
 ext4_mb_regular_allocator+0x1600/0x2520 fs/ext4/mballoc.c:2729
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5515
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4713
 vfs_fallocate+0x459/0x6a0 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000a -> 0xffffffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7573 Comm: syz-executor.2 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/09/02 17:04 upstream 4ac6d90867a4 d0f0970b .config log report info KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order
ci2-upstream-kcsan-gce 2021/08/31 14:43 upstream b91db6a0b52e 7eb7e152 .config log report info KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order
ci2-upstream-kcsan-gce 2021/08/21 08:04 upstream fa54d366a6e4 b599f2fc .config log report info KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order
ci2-upstream-kcsan-gce 2021/08/15 19:40 upstream ecf93431963a 2489ab88 .config log report info KCSAN: data-race in ext4_mb_good_group / mb_set_largest_free_order
* Struck through repros no longer work on HEAD.