From: Boqun Feng <boqun.feng@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Andrea Parri <parri.andrea@gmail.com>,
Boqun Feng <boqun.feng@gmail.com>
Subject: [RFC tip/locking/lockdep v5 00/17] lockdep: Support deadlock detection for recursive read locks
Date: Thu, 22 Feb 2018 15:08:47 +0800 [thread overview]
Message-ID: <20180222070904.548-1-boqun.feng@gmail.com> (raw)
Hi Ingo and Peter,
This is V5 for recursive read lock support in lockdep. The changes since
V4 are quite trivial:
* Fix some wording issues in patch #16 as pointed out by Randy
Dunlap
I added the explanation about reasoning in patch #16 in V4, which will
help understand this whole series. This patchset is based on v4.16-rc2.
Changes since V3:
* Reduce the unnecessary cost in structure lock_list as suggested
by Peter Zijlstra
* Add documentation for explanation of the reasoning in recursive
read lock deadlock detection.
* Add comments before bfs() describing the greedy search we use in
BFS for strong dependency paths.
* Add myself as a reviewer for LOCKING PRIMITIVES so that if there
is any performance regression, log misunderstanding or false
positives, people know who to blame^Wask help from.
V1: https://marc.info/?l=linux-kernel&m=150393341825453
V2: https://marc.info/?l=linux-kernel&m=150468649417950
V3: https://marc.info/?l=linux-kernel&m=150637795424969
V4: https://marc.info/?l=linux-kernel&m=151550860121565
As Peter pointed out:
https://marc.info/?l=linux-kernel&m=150349072023540
The lockdep current has a limit support for recursive read locks, the
deadlock case as follow could not be detected:
read_lock(A);
lock(B);
lock(B);
write_lock(A);
I got some inspiration from Gautham R Shenoy:
https://lwn.net/Articles/332801/
, and came up with this series.
The basic idea is:
* Add recursive read locks into the graph
* Classify dependencies into -(RR)->, -(NR)->, -(RN)->,
-(NN)->, where R stands for recursive read lock, N stands for
other locks(i.e. non-recursive read locks and write locks).
* Define strong dependency paths as the paths of dependencies
don't have two adjacent dependencies as -(*R)-> and -(R*)->.
* Extend __bfs() to only traverse on strong dependency paths.
* If __bfs() finds a strong dependency circle, then a deadlock is
reported.
The whole series consists of 17 patches:
1. Do a clean up on the return value of __bfs() and its friends.
2. Make __bfs() able to visit every dependency until a match is
found. The old version of __bfs() could only visit each lock
class once, and this is insufficient if we are going to add
recursive read locks into the dependency graph.
3. Redefine LOCK*_STATE*, now LOCK*_STATE_RR stand for recursive
read lock only and LOCK*_STATE stand for write lock and
non-recursive read lock.
4-5 Extend __bfs() to be able to traverse the stong dependency
patchs after recursive read locks added into the graph.
6-8 Adjust check_redundant(), check_noncircular() and
check_irq_usage() with recursive read locks into consideration.
9. Finally add recursive read locks into the dependency graph.
10-11 Adjust lock cache chain key generation with recursive read locks
into consideration, and provide a test case.
12-13 Add more test cases.
14. Revert commit d82fed752942 ("locking/lockdep/selftests: Fix
mixed read-write ABBA tests"),
15. Reduce the extra size cost of lock_list to zero
16. Add documentation for recursive read lock deadlock detection
reasoning
17. Add myself as a LOCKING PRIMITIVES reviewer.
This series passed all the lockdep selftest cases(including those I
introduce).
Test and comments are welcome!
Regards,
Boqun
next reply other threads:[~2018-02-22 7:05 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-22 7:08 Boqun Feng [this message]
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 01/17] lockdep: Demagic the return value of BFS Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 02/17] lockdep: Make __bfs() visit every dependency until a match Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 03/17] lockdep: Redefine LOCK_*_STATE* bits Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 04/17] lockdep: Introduce lock_list::dep Boqun Feng
2018-02-23 11:55 ` Peter Zijlstra
2018-02-23 12:37 ` Boqun Feng
2018-02-24 5:32 ` Boqun Feng
2018-02-24 6:30 ` Boqun Feng
2018-02-24 8:38 ` Peter Zijlstra
2018-02-24 9:00 ` Boqun Feng
2018-02-24 9:26 ` Boqun Feng
2018-02-26 9:00 ` Peter Zijlstra
2018-02-26 10:15 ` Boqun Feng
2018-02-26 10:20 ` Boqun Feng
2018-02-24 7:31 ` Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 05/17] lockdep: Extend __bfs() to work with multiple kinds of dependencies Boqun Feng
2018-02-22 14:26 ` Peter Zijlstra
2018-02-22 15:12 ` Boqun Feng
2018-02-22 15:30 ` Peter Zijlstra
2018-02-22 15:51 ` Peter Zijlstra
2018-02-22 16:31 ` Boqun Feng
2018-02-23 5:02 ` Boqun Feng
2018-02-23 11:15 ` Peter Zijlstra
2018-02-22 16:08 ` Peter Zijlstra
2018-02-22 16:34 ` Boqun Feng
2018-02-22 16:32 ` Peter Zijlstra
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 06/17] lockdep: Support deadlock detection for recursive read in check_noncircular() Boqun Feng
2018-02-22 14:54 ` Peter Zijlstra
2018-02-22 15:16 ` Peter Zijlstra
2018-02-22 15:44 ` Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 07/17] lockdep: Adjust check_redundant() for recursive read change Boqun Feng
2018-02-22 17:29 ` Peter Zijlstra
2018-03-16 8:20 ` Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 08/17] lockdep: Fix recursive read lock related safe->unsafe detection Boqun Feng
2018-02-22 17:41 ` Peter Zijlstra
2018-02-22 17:46 ` Peter Zijlstra
2018-02-23 8:21 ` Boqun Feng
2018-02-23 8:58 ` Boqun Feng
2018-02-23 11:36 ` Peter Zijlstra
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 09/17] lockdep: Add recursive read locks into dependency graph Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 10/17] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 11/17] lockdep: Take read/write status in consideration when generate chainkey Boqun Feng
2018-02-22 7:08 ` [RFC tip/locking/lockdep v5 12/17] lockdep/selftest: Unleash irq_read_recursion2 and add more Boqun Feng
2018-02-22 7:09 ` [RFC tip/locking/lockdep v5 13/17] lockdep/selftest: Add more recursive read related test cases Boqun Feng
2018-02-22 7:09 ` [RFC tip/locking/lockdep v5 14/17] Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests" Boqun Feng
2018-02-22 7:09 ` [RFC tip/locking/lockdep v5 15/17] lockdep: Reduce the size of lock_list Boqun Feng
2018-02-23 11:38 ` Peter Zijlstra
2018-02-23 12:40 ` Boqun Feng
2018-02-22 7:09 ` [RFC tip/locking/lockdep v5 16/17] lockdep: Documention for recursive read lock detection reasoning Boqun Feng
2018-02-24 22:53 ` Andrea Parri
2018-02-27 2:32 ` Boqun Feng
2018-02-22 7:09 ` [RFC tip/locking/lockdep v5 17/17] MAINTAINERS: Add myself as a LOCKING PRIMITIVES reviewer Boqun Feng
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