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Message-Id: <1646377603-19730-1-git-send-email-byungchul.park@lge.com>
Date: Fri, 4 Mar 2022 16:06:19 +0900
From: Byungchul Park <byungchul.park@....com>
To: torvalds@...ux-foundation.org
Cc: damien.lemoal@...nsource.wdc.com, linux-ide@...r.kernel.org,
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Subject: [PATCH v4 00/24] DEPT(Dependency Tracker)
Hi Linus and folks,
I've been developing a tool for detecting deadlock possibilities by
tracking wait/event rather than lock(?) acquisition order to try to
cover all synchonization machanisms. It's done on v5.17-rc1 tag.
https://github.com/lgebyungchulpark/linux-dept/commits/dept1.14_on_v5.17-rc1
Benifit:
0. Works with all lock primitives.
1. Works with wait_for_completion()/complete().
2. Works with 'wait' on PG_locked.
3. Works with 'wait' on PG_writeback.
4. Works with swait/wakeup.
5. Works with waitqueue.
6. Multiple reports are allowed.
7. Deduplication control on multiple reports.
8. Withstand false positives thanks to 6.
9. Easy to tag any wait/event.
Future work:
0. To make it more stable.
1. To separates Dept from Lockdep.
2. To improves performance in terms of time and space.
3. To use Dept as a dependency engine for Lockdep.
4. To add any missing tags of wait/event in the kernel.
5. To deduplicate stack trace.
How to interpret reports:
1. E(event) in each context cannot be triggered because of the
W(wait) that cannot be woken.
2. The stack trace helping find the problematic code is located
in each conext's detail.
Thanks,
Byungchul
---
Changes from v3:
1. Dept shouldn't create dependencies between different depths
of a class that were indicated by *_lock_nested(). Dept
normally doesn't but it does once another lock class comes
in. So fixed it. (feedback from Hyeonggon)
2. Dept considered a wait as a real wait once getting to
__schedule() even if it has been set to TASK_RUNNING by wake
up sources in advance. Fixed it so that Dept doesn't consider
the case as a real wait. (feedback from Jan Kara)
3. Stop tracking dependencies with a map once the event
associated with the map has been handled. Dept will start to
work with the map again, on the next sleep.
Changes from v2:
1. Disable Dept on bit_wait_table[] in sched/wait_bit.c
reporting a lot of false positives, which is my fault.
Wait/event for bit_wait_table[] should've been tagged in a
higher layer for better work, which is a future work.
(feedback from Jan Kara)
2. Disable Dept on crypto_larval's completion to prevent a false
positive.
Changes from v1:
1. Fix coding style and typo. (feedback from Steven)
2. Distinguish each work context from another in workqueue.
3. Skip checking lock acquisition with nest_lock, which is about
correct lock usage that should be checked by Lockdep.
Changes from RFC:
1. Prevent adding a wait tag at prepare_to_wait() but __schedule().
(feedback from Linus and Matthew)
2. Use try version at lockdep_acquire_cpus_lock() annotation.
3. Distinguish each syscall context from another.
Byungchul Park (24):
llist: Move llist_{head,node} definition to types.h
dept: Implement Dept(Dependency Tracker)
dept: Embed Dept data in Lockdep
dept: Add a API for skipping dependency check temporarily
dept: Apply Dept to spinlock
dept: Apply Dept to mutex families
dept: Apply Dept to rwlock
dept: Apply Dept to wait_for_completion()/complete()
dept: Apply Dept to seqlock
dept: Apply Dept to rwsem
dept: Add proc knobs to show stats and dependency graph
dept: Introduce split map concept and new APIs for them
dept: Apply Dept to wait/event of PG_{locked,writeback}
dept: Apply SDT to swait
dept: Apply SDT to wait(waitqueue)
locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread
dept: Distinguish each syscall context from another
dept: Distinguish each work from another
dept: Disable Dept within the wait_bit layer by default
dept: Add nocheck version of init_completion()
dept: Disable Dept on struct crypto_larval's completion for now
dept: Don't create dependencies between different depths in any case
dept: Let it work with real sleeps in __schedule()
dept: Disable Dept on that map once it's been handled until next turn
crypto/api.c | 7 +-
include/linux/completion.h | 50 +-
include/linux/dept.h | 535 +++++++
include/linux/dept_page.h | 78 ++
include/linux/dept_sdt.h | 62 +
include/linux/hardirq.h | 3 +
include/linux/irqflags.h | 33 +-
include/linux/llist.h | 8 -
include/linux/lockdep.h | 158 ++-
include/linux/lockdep_types.h | 3 +
include/linux/mutex.h | 33 +
include/linux/page-flags.h | 45 +-
include/linux/pagemap.h | 7 +-
include/linux/percpu-rwsem.h | 10 +-
include/linux/rtmutex.h | 7 +
include/linux/rwlock.h | 52 +
include/linux/rwlock_api_smp.h | 8 +-
include/linux/rwlock_types.h | 7 +
include/linux/rwsem.h | 33 +
include/linux/sched.h | 7 +
include/linux/seqlock.h | 59 +-
include/linux/spinlock.h | 26 +
include/linux/spinlock_types_raw.h | 13 +
include/linux/swait.h | 4 +
include/linux/types.h | 8 +
include/linux/wait.h | 6 +-
init/init_task.c | 2 +
init/main.c | 4 +
kernel/Makefile | 1 +
kernel/cpu.c | 2 +-
kernel/dependency/Makefile | 4 +
kernel/dependency/dept.c | 2716 ++++++++++++++++++++++++++++++++++++
kernel/dependency/dept_hash.h | 10 +
kernel/dependency/dept_internal.h | 26 +
kernel/dependency/dept_object.h | 13 +
kernel/dependency/dept_proc.c | 92 ++
kernel/entry/common.c | 3 +
kernel/exit.c | 1 +
kernel/fork.c | 2 +
kernel/locking/lockdep.c | 12 +-
kernel/module.c | 2 +
kernel/sched/completion.c | 12 +-
kernel/sched/core.c | 8 +
kernel/sched/swait.c | 10 +
kernel/sched/wait.c | 16 +
kernel/sched/wait_bit.c | 5 +-
kernel/softirq.c | 6 +-
kernel/trace/trace_preemptirq.c | 19 +-
kernel/workqueue.c | 3 +
lib/Kconfig.debug | 21 +
mm/filemap.c | 68 +
mm/page_ext.c | 5 +
52 files changed, 4266 insertions(+), 59 deletions(-)
create mode 100644 include/linux/dept.h
create mode 100644 include/linux/dept_page.h
create mode 100644 include/linux/dept_sdt.h
create mode 100644 kernel/dependency/Makefile
create mode 100644 kernel/dependency/dept.c
create mode 100644 kernel/dependency/dept_hash.h
create mode 100644 kernel/dependency/dept_internal.h
create mode 100644 kernel/dependency/dept_object.h
create mode 100644 kernel/dependency/dept_proc.c
--
1.9.1
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