syzbot


KCSAN: data-race in deadline_remove_request / ll_back_merge_fn (2)

Status: auto-closed as invalid on 2022/08/27 19:31
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 132d, last: 132d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in deadline_remove_request / ll_back_merge_fn 2 1033d 1036d 0/24 auto-closed as invalid on 2020/04/14 00:20

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

write to 0xffff888101e9d6a8 of 8 bytes by task 42 on cpu 1:
 deadline_remove_request+0x16b/0x190 block/mq-deadline.c:183
 deadline_move_request block/mq-deadline.c:249 [inline]
 __dd_dispatch_request+0x411/0x4a0 block/mq-deadline.c:465
 dd_dispatch_request+0x1d0/0x2b0 block/mq-deadline.c:531
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:121 [inline]
 blk_mq_do_dispatch_sched+0x219/0x7f0 block/blk-mq-sched.c:187
 __blk_mq_sched_dispatch_requests+0x1cd/0x270
 blk_mq_sched_dispatch_requests+0x8f/0xf0 block/blk-mq-sched.c:339
 __blk_mq_run_hw_queue+0x7e/0x100 block/blk-mq.c:2013
 blk_mq_run_work_fn+0x3d/0x50 block/blk-mq.c:2336
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

read to 0xffff888101e9d6a8 of 8 bytes by task 1405 on cpu 0:
 req_set_nomerge block/blk.h:335 [inline]
 ll_back_merge_fn+0x2b3/0x4a0 block/blk-merge.c:615
 bio_attempt_back_merge+0x35/0x2f0 block/blk-merge.c:921
 blk_attempt_bio_merge+0x438/0x480 block/blk-merge.c:1003
 blk_attempt_plug_merge+0xb3/0xf0 block/blk-merge.c:1050
 blk_mq_attempt_bio_merge block/blk-mq.c:2707 [inline]
 blk_mq_get_new_requests block/blk-mq.c:2730 [inline]
 blk_mq_submit_bio+0x717/0xe50 block/blk-mq.c:2819
 __submit_bio block/blk-core.c:648 [inline]
 __submit_bio_noacct_mq block/blk-core.c:725 [inline]
 submit_bio_noacct_nocheck+0x83d/0xaa0 block/blk-core.c:742
 submit_bio_noacct+0x690/0x7f0 block/blk-core.c:849
 submit_bio+0xfb/0x110
 ext4_io_submit+0x86/0xa0 fs/ext4/page-io.c:378
 ext4_writepage+0x44c/0x750 fs/ext4/inode.c:2069
 __writepage+0x38/0xd0 mm/page-writeback.c:2399
 write_cache_pages+0x443/0xa30 mm/page-writeback.c:2334
 generic_writepages+0x7c/0xc0 mm/page-writeback.c:2425
 jbd2_journal_submit_inode_data_buffers+0xd0/0xf0 fs/jbd2/commit.c:208
 ext4_journal_submit_inode_data_buffers+0x53/0x140 fs/ext4/super.c:549
 journal_submit_data_buffers+0xf0/0x260 fs/jbd2/commit.c:258
 jbd2_journal_commit_transaction+0x764/0x3180 fs/jbd2/commit.c:582
 kjournald2+0x253/0x460 fs/jbd2/journal.c:213
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30

value changed: 0xffff888103695140 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1405 Comm: jbd2/sda1-8 Not tainted 5.19.0-rc7-syzkaller-00190-g70664fc10c0d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/07/23 19:20 upstream 70664fc10c0d 22343af4 .config log report info KCSAN: data-race in deadline_remove_request / ll_back_merge_fn
* Struck through repros no longer work on HEAD.