bisecting cause commit starting from ad347abe4a9876b1f65f408ab467137e88f77eb4 building syzkaller on 1ba81399e2d03b53a7e631c4ab05f25af1fb1911 testing commit ad347abe4a9876b1f65f408ab467137e88f77eb4 with gcc (GCC) 10.2.1 20210217 kernel signature: c2d8cc2b680573b1fe5880a753a4343e3571c3459ec88ea869c66fc676422b4e all runs: crashed: kernel BUG in ext4_writepages testing release v5.12 testing commit 9f4ad9e425a1d3b6a34617b8ea226d56a119a717 with gcc (GCC) 10.2.1 20210217 kernel signature: 20a3195b0c2adea39c30d2e9f830a6fa425a34f031f28cd84a5fc4bf09ce8f4d all runs: crashed: kernel BUG in ext4_writepages testing release v5.11 testing commit f40ddce88593482919761f74910f42f4b84c004b with gcc (GCC) 10.2.1 20210217 kernel signature: 22b26ae1e3be417e2ad324e47433a262e845b6471dfc09f4fa2f647b3330df8e all runs: crashed: kernel BUG in ext4_writepages testing release v5.10 testing commit 2c85ebc57b3e1817b6ce1a6b703928e113a90442 with gcc (GCC) 10.2.1 20210217 kernel signature: 8f55ba93fd53951cac9b68b979c728becbef461543abacbe99727324ff41baf6 all runs: crashed: kernel BUG in ext4_writepages testing release v5.9 testing commit bbf5c979011a099af5dc76498918ed7df445635b with gcc (GCC) 10.2.1 20210217 kernel signature: f654d07eeb7c456b884d4afbd5bc4d393d1b1677ed42327eee0eaef482a1d4de all runs: crashed: kernel BUG in ext4_writepages testing release v5.8 testing commit bcf876870b95592b52519ed4aafcf9d95999bc9c with gcc (GCC) 8.4.1 20210217 kernel signature: 1063ebaf54671db7804acf12269942e9a5933d00bfb78bb5cf898a218f3c1d07 all runs: crashed: kernel BUG in ext4_writepages testing release v5.7 testing commit 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162 with gcc (GCC) 8.4.1 20210217 kernel signature: 3856a09b3d94850025e3ae49dd0f33b972955333e09df445983a6a278d85997d all runs: crashed: kernel BUG in ext4_writepages testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.4.1 20210217 kernel signature: a3b93acd1315ac27fd28df3f64d6ec371b03ab2c3dca6caf01eeb51039157802 all runs: crashed: kernel BUG in ext4_writepages testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.4.1 20210217 kernel signature: 56b75590080ebce41771eb20fb3a18a21250479d609f5cd866a9e9cf93705477 all runs: crashed: kernel BUG in ext4_writepages testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.4.1 20210217 kernel signature: c6858008ba2dd87e1e0dfa3f7b77c43b09b0dc43a2a0142524db4f19e9503c6e all runs: crashed: kernel BUG in ext4_writepages testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.4.1 20210217 kernel signature: aae18b99c108d4b86fb7c39080c3a8373862416e546d19d54d8a47dcb2701455 all runs: crashed: kernel BUG in ext4_writepages testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.4.1 20210217 kernel signature: e13f671b39135f0fd02c29412f7240f2d07a062c4a49e605a3f48631956d18cb all runs: OK # git bisect start 4d856f72c10ecb060868ed10ff1b1453943fc6c8 0ecfebd2b52404ae0c54a878c872bb93363ada36 Bisecting: 7848 revisions left to test after this (roughly 13 steps) [43c95d3694cc448fdf50bd53b7ff3a5bb4655883] Merge tag 'pinctrl-v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl testing commit 43c95d3694cc448fdf50bd53b7ff3a5bb4655883 with gcc (GCC) 8.4.1 20210217 kernel signature: eabc8bbc5dcf609fab110f03d71d6bf92f6277515c995067afc0f2a5d60231f3 all runs: crashed: kernel BUG in ext4_writepages # git bisect bad 43c95d3694cc448fdf50bd53b7ff3a5bb4655883 Bisecting: 4619 revisions left to test after this (roughly 12 steps) [8f6ccf6159aed1f04c6d179f61f6fb2691261e84] Merge tag 'clone3-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux testing commit 8f6ccf6159aed1f04c6d179f61f6fb2691261e84 with gcc (GCC) 8.4.1 20210217 kernel signature: 5cde3d358e6e31f8efcca9abd8ba707b4a789878c8431b21bec8ddb40ad6843a all runs: crashed: kernel BUG in ext4_writepages # git bisect bad 8f6ccf6159aed1f04c6d179f61f6fb2691261e84 Bisecting: 1595 revisions left to test after this (roughly 11 steps) [ed63b9c873601ca113da5c7b1745e3946493e9f3] Merge tag 'media/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media testing commit ed63b9c873601ca113da5c7b1745e3946493e9f3 with gcc (GCC) 8.4.1 20210217 kernel signature: 489f953c829e92bdd1d66f1eab4f4ec3032140e73c5a05953ec0dde4cb8ae92b run #0: OK run #1: OK run #2: OK run #3: OK run #4: OK run #5: OK run #6: OK run #7: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #8: OK run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! reproducer seems to be flaky # git bisect bad ed63b9c873601ca113da5c7b1745e3946493e9f3 Bisecting: 849 revisions left to test after this (roughly 10 steps) [4d2fa8b44b891f0da5ceda3e5a1402ccf0ab6f26] Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 testing commit 4d2fa8b44b891f0da5ceda3e5a1402ccf0ab6f26 with gcc (GCC) 8.4.1 20210217 kernel signature: db92b54321613cb58594ff6599e5df01c4839c803e7addc5aa00f3d0ad8b36ab run #0: OK run #1: OK run #2: OK run #3: OK run #4: OK run #5: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #6: OK run #7: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #8: OK run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #10: OK run #11: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #12: OK run #13: OK run #14: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #15: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #16: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #17: OK run #18: OK run #19: OK # git bisect bad 4d2fa8b44b891f0da5ceda3e5a1402ccf0ab6f26 Bisecting: 414 revisions left to test after this (roughly 9 steps) [46f1ec23a46940846f86a91c46f7119d8a8b5de1] Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip testing commit 46f1ec23a46940846f86a91c46f7119d8a8b5de1 with gcc (GCC) 8.4.1 20210217 kernel signature: dfda2ba7e8733efa75f7f97da6a14bf13bf0e460d485e349c092ca3c1878a101 all runs: OK # git bisect good 46f1ec23a46940846f86a91c46f7119d8a8b5de1 Bisecting: 210 revisions left to test after this (roughly 8 steps) [222a21d29521d144f3dd7a0bc4d4020e448f0126] Merge branch 'x86-topology-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip testing commit 222a21d29521d144f3dd7a0bc4d4020e448f0126 with gcc (GCC) 8.4.1 20210217 kernel signature: 3765876c9bc36bab9ef402f2ebc53775a5fc1d40917ebf82e015bcb836762816 run #0: OK run #1: OK run #2: OK run #3: OK run #4: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #5: OK run #6: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #7: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #8: OK run #9: OK run #10: OK run #11: OK run #12: OK run #13: OK run #14: OK run #15: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #16: OK run #17: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #18: OK run #19: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! # git bisect bad 222a21d29521d144f3dd7a0bc4d4020e448f0126 Bisecting: 102 revisions left to test after this (roughly 7 steps) [090bc5a2a91499c1fd64b78d125daa6ca5531d38] Merge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip testing commit 090bc5a2a91499c1fd64b78d125daa6ca5531d38 with gcc (GCC) 8.4.1 20210217 kernel signature: 20247763f040077da8fb091db956448929a7b84ad99443cd6009328b3d1f7a1c run #0: OK run #1: OK run #2: OK run #3: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #4: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #5: OK run #6: OK run #7: OK run #8: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #9: OK run #10: OK run #11: OK run #12: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #13: OK run #14: OK run #15: OK run #16: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #17: OK run #18: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #19: OK # git bisect bad 090bc5a2a91499c1fd64b78d125daa6ca5531d38 Bisecting: 50 revisions left to test after this (roughly 6 steps) [410df0c5748f6c5a53847d2acb163dc7cd8b6c51] Merge tag 'v5.2-rc5' into locking/core, to pick up fixes testing commit 410df0c5748f6c5a53847d2acb163dc7cd8b6c51 with gcc (GCC) 8.4.1 20210217 kernel signature: 22cb3c523e662f5924eac9d3246a63ca833a48a6a54c76254ddaa15c4dd3f2bc run #0: OK run #1: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #2: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #3: OK run #4: OK run #5: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #6: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #7: OK run #8: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #10: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #11: OK run #12: OK run #13: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #14: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #15: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #16: OK run #17: OK run #18: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #19: OK # git bisect bad 410df0c5748f6c5a53847d2acb163dc7cd8b6c51 Bisecting: 24 revisions left to test after this (roughly 5 steps) [091806515124b20f8cff7927b4b7ff399483b109] locking/lockdep: Consolidate lock usage bit initialization testing commit 091806515124b20f8cff7927b4b7ff399483b109 with gcc (GCC) 8.4.1 20210217 kernel signature: 501ffb89a60ddfe87a2a4ded1fe5fdaacc666c21d74bae796da0049a27b60512 run #0: OK run #1: OK run #2: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #3: OK run #4: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #5: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #6: OK run #7: OK run #8: OK run #9: OK run #10: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #11: OK run #12: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #13: OK run #14: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #15: OK run #16: OK run #17: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #18: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #19: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! # git bisect bad 091806515124b20f8cff7927b4b7ff399483b109 Bisecting: 12 revisions left to test after this (roughly 4 steps) [f6ec8829ac9d59b637366c13038f15d6f6156fe1] locking/lockdep: Define INITIAL_CHAIN_KEY for chain keys to start with testing commit f6ec8829ac9d59b637366c13038f15d6f6156fe1 with gcc (GCC) 8.4.1 20210217 kernel signature: f9f0907e285b7a3946558810f451103971c25f2757e0138ef555e7ad3708f7ef all runs: OK # git bisect good f6ec8829ac9d59b637366c13038f15d6f6156fe1 Bisecting: 6 revisions left to test after this (roughly 3 steps) [77a806922cfdebcf3ae89d31a8b592a7f7fbe537] locking/lockdep: Avoid constant checks in __bfs by using offset reference testing commit 77a806922cfdebcf3ae89d31a8b592a7f7fbe537 with gcc (GCC) 8.4.1 20210217 kernel signature: b2f3f14c93b8f9d89af3406e5ebe9cca09f9aad016c8e6be16115bf96017c232 all runs: OK # git bisect good 77a806922cfdebcf3ae89d31a8b592a7f7fbe537 Bisecting: 3 revisions left to test after this (roughly 2 steps) [4609c4f963f353613812f999bb027aac795bcde8] locking/lockdep: Remove redundant argument in check_deadlock testing commit 4609c4f963f353613812f999bb027aac795bcde8 with gcc (GCC) 8.4.1 20210217 kernel signature: 11f0babb2ba2415923d751e3eb1ce21f51875bc46113b5d6f6b6f7c905cff881 all runs: OK # git bisect good 4609c4f963f353613812f999bb027aac795bcde8 Bisecting: 1 revision left to test after this (roughly 1 step) [8c2c2b449aa50463ba4cc1f33cdfc98750ed03ab] locking/lockdep: Refactorize check_noncircular and check_redundant testing commit 8c2c2b449aa50463ba4cc1f33cdfc98750ed03ab with gcc (GCC) 8.4.1 20210217 kernel signature: f121117745cf8676059367441897b23a2cc1625cab66a85cf65f1e2314d5ca46 all runs: OK # git bisect good 8c2c2b449aa50463ba4cc1f33cdfc98750ed03ab Bisecting: 0 revisions left to test after this (roughly 0 steps) [68e9dc29f8f42c79d2a3755223ed910ce36b4ae2] locking/lockdep: Check redundant dependency only when CONFIG_LOCKDEP_SMALL testing commit 68e9dc29f8f42c79d2a3755223ed910ce36b4ae2 with gcc (GCC) 8.4.1 20210217 kernel signature: 1e3f36fe1b86a881436e73df65b582f9688cf5fb6a68387bb94553744e3941d5 run #0: OK run #1: OK run #2: OK run #3: OK run #4: OK run #5: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #6: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #7: OK run #8: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #9: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #10: OK run #11: OK run #12: OK run #13: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #14: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #15: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #16: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #17: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #18: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! run #19: crashed: BUG: MAX_STACK_TRACE_ENTRIES too low! # git bisect bad 68e9dc29f8f42c79d2a3755223ed910ce36b4ae2 68e9dc29f8f42c79d2a3755223ed910ce36b4ae2 is the first bad commit commit 68e9dc29f8f42c79d2a3755223ed910ce36b4ae2 Author: Yuyang Du Date: Mon May 6 16:19:36 2019 +0800 locking/lockdep: Check redundant dependency only when CONFIG_LOCKDEP_SMALL As Peter has put it all sound and complete for the cause, I simply quote: "It (check_redundant) was added for cross-release (which has since been reverted) which would generate a lot of redundant links (IIRC) but having it makes the reports more convoluted -- basically, if we had an A-B-C relation, then A-C will not be added to the graph because it is already covered. This then means any report will include B, even though a shorter cycle might have been possible." This would increase the number of direct dependencies. For a simple workload (make clean; reboot; make vmlinux -j8), the data looks like this: CONFIG_LOCKDEP_SMALL: direct dependencies: 6926 !CONFIG_LOCKDEP_SMALL: direct dependencies: 9052 (+30.7%) Suggested-by: Peter Zijlstra (Intel) Signed-off-by: Yuyang Du Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: bvanassche@acm.org Cc: frederic@kernel.org Cc: ming.lei@redhat.com Cc: will.deacon@arm.com Link: https://lkml.kernel.org/r/20190506081939.74287-21-duyuyang@gmail.com Signed-off-by: Ingo Molnar kernel/locking/lockdep.c | 4 ++++ 1 file changed, 4 insertions(+) culprit signature: 1e3f36fe1b86a881436e73df65b582f9688cf5fb6a68387bb94553744e3941d5 parent signature: f121117745cf8676059367441897b23a2cc1625cab66a85cf65f1e2314d5ca46 Reproducer flagged being flaky revisions tested: 26, total time: 5h36m24.323708413s (build: 2h53m44.97046557s, test: 2h38m16.721657986s) first bad commit: 68e9dc29f8f42c79d2a3755223ed910ce36b4ae2 locking/lockdep: Check redundant dependency only when CONFIG_LOCKDEP_SMALL recipients (to): ["duyuyang@gmail.com" "mingo@kernel.org" "peterz@infradead.org"] recipients (cc): [] crash: BUG: MAX_STACK_TRACE_ENTRIES too low! BUG: MAX_STACK_TRACE_ENTRIES too low! turning off the locking correctness validator. CPU: 1 PID: 9003 Comm: syz-executor.2 Not tainted 5.2.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x86/0xca lib/dump_stack.c:113 save_trace kernel/locking/lockdep.c:471 [inline] save_trace.isra.10.cold.23+0x13/0x18 kernel/locking/lockdep.c:456 check_prev_add kernel/locking/lockdep.c:2442 [inline] check_prevs_add kernel/locking/lockdep.c:2502 [inline] validate_chain kernel/locking/lockdep.c:2892 [inline] __lock_acquire+0x457d/0x5020 kernel/locking/lockdep.c:3886 lock_acquire+0x111/0x2d0 kernel/locking/lockdep.c:4402 flush_workqueue+0xf2/0x1360 kernel/workqueue.c:2774 ext4_sync_fs+0x11d/0x770 fs/ext4/super.c:5116 __sync_filesystem fs/sync.c:39 [inline] sync_filesystem+0xd4/0x200 fs/sync.c:64 generic_shutdown_super+0x69/0x330 fs/super.c:444 kill_block_super+0x96/0xe0 fs/super.c:1373 deactivate_locked_super+0x77/0xd0 fs/super.c:331 deactivate_super fs/super.c:362 [inline] deactivate_super+0x13f/0x160 fs/super.c:358 cleanup_mnt+0xa3/0x140 fs/namespace.c:1120 __cleanup_mnt+0xd/0x10 fs/namespace.c:1127 task_work_run+0x108/0x180 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:185 [inline] exit_to_usermode_loop+0x129/0x150 arch/x86/entry/common.c:168 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x3e1/0x480 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x467a37 Code: ff d0 48 89 c7 b8 3c 00 00 00 0f 05 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdd9fe3e28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000467a37 RDX: 00007ffdd9fe3efb RSI: 0000000000000002 RDI: 00007ffdd9fe3ef0 RBP: 00007ffdd9fe3ef0 R08: 00000000ffffffff R09: 00007ffdd9fe3cc0 R10: 000055555686f8e3 R11: 0000000000000246 R12: 00000000004bee70 R13: 00007ffdd9fe4fc0 R14: 000055555686f810 R15: 00007ffdd9fe5000