syzbot


KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu (6)

Status: moderation: reported on 2024/06/24 11:04
Subsystems: fs mm
[Documentation on labels]
Reported-by: syzbot+7139e8dee7b64af430c7@syzkaller.appspotmail.com
First crash: 25d, last: 25d
Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu (3) fs mm 3 1123d 1155d 0/27 auto-closed as invalid on 2021/07/27 20:37
upstream KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu (5) fs mm 1 416d 416d 0/27 auto-obsoleted due to no activity on 2023/07/03 22:15
upstream KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu (4) fs mm 1 1065d 1065d 0/27 auto-closed as invalid on 2021/09/23 01:41
upstream KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu (2) fs mm 1 1306d 1306d 0/27 auto-closed as invalid on 2021/01/25 01:30
upstream KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu fs mm 1 1363d 1363d 0/27 auto-closed as invalid on 2020/11/29 19:57

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

write to 0xffff8881088a61c8 of 4 bytes by task 27496 on cpu 0:
 fprop_reflect_period_percpu+0x170/0x1a0 lib/flex_proportions.c:134
 fprop_fraction_percpu+0x98/0x150 lib/flex_proportions.c:156
 __wb_calc_thresh mm/page-writeback.c:875 [inline]
 wb_over_bg_thresh+0x203/0x760 mm/page-writeback.c:2120
 wb_check_background_flush fs/fs-writeback.c:2189 [inline]
 wb_do_writeback fs/fs-writeback.c:2287 [inline]
 wb_workfn+0x643/0x940 fs/fs-writeback.c:2314
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x730 kernel/workqueue.c:3393
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881088a61c8 of 4 bytes by interrupt on cpu 1:
 fprop_reflect_period_percpu+0x32/0x1a0 lib/flex_proportions.c:115
 __fprop_add_percpu lib/flex_proportions.c:142 [inline]
 __fprop_add_percpu_max+0x58/0x180 lib/flex_proportions.c:200
 wb_domain_writeout_add mm/page-writeback.c:560 [inline]
 __wb_writeout_add+0x77/0x1d0 mm/page-writeback.c:584
 __folio_end_writeback+0x215/0x4a0 mm/page-writeback.c:3042
 folio_end_writeback+0x74/0x1f0 mm/filemap.c:1632
 mpage_write_end_io+0x281/0x3a0 fs/mpage.c:72
 bio_endio+0x369/0x410 block/bio.c:1636
 blk_update_request+0x382/0x880 block/blk-mq.c:929
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1057
 lo_complete_rq+0xce/0x180 drivers/block/loop.c:389
 blk_complete_reqs block/blk-mq.c:1132 [inline]
 blk_done_softirq+0x74/0xb0 block/blk-mq.c:1137
 handle_softirqs+0xc3/0x280 kernel/softirq.c:554
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:928
 smpboot_thread_fn+0x31c/0x4c0 kernel/smpboot.c:164
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000180 -> 0x00000183

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23 Comm: ksoftirqd/1 Tainted: G        W          6.10.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/24 11:04 upstream f2661062f16b edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fprop_reflect_period_percpu / fprop_reflect_period_percpu
* Struck through repros no longer work on HEAD.