From: Boqun Feng <boqun.feng@gmail.com>
To: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Waiman Long <longman@redhat.com>,
Boqun Feng <boqun.feng@gmail.com>
Subject: [RFC v7 00/19] lockdep: Support deadlock detection for recursive read locks
Date: Fri, 7 Aug 2020 15:42:19 +0800 [thread overview]
Message-ID: <20200807074238.1632519-1-boqun.feng@gmail.com> (raw)
Hi Peter and Waiman,
As promised, this is the updated version of my previous lockdep patchset
for recursive read lock support. It's based on v5.8. Previous versions
can be found at:
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
V5: https://marc.info/?l=linux-kernel&m=151928315529363
V6: https://lore.kernel.org/lkml/20180411135110.9217-1-boqun.feng@gmail.com/
Changes since last version:
* I change the detection algorithm which I present in 2018
plumbers [1], you can find the explanation of the detection
method in patch #2.
* Adjust the irq safe->unsafe changes from Frederic Weisbecker
* Add more tests.
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 -(SR)->, -(ER)->, -(SN)->,
-(EN)->, where R stands for recursive read lock, N stands for
other locks(i.e. non-recursive read locks and write locks), S
stands for shared locks (read locks, no matter recursive or
not), and E stands for exclusive locks (i.e. write locks)
* Define strong dependency paths as the paths of dependencies
don't have two adjacent dependencies as -(*R)-> and -(S*)->.
* 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 19 patches:
1. Add documentation for recursive read lock deadlock detection
reasoning
2. Annotate read_lock() correctly (with queued_read_lock()
semantics into consideration)
3. Do a clean up on the return value of __bfs() and its friends.
4. 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.
5. Reduce the size of lock_list::distance.
6-7 Extend __bfs() to be able to traverse the stong dependency
patchs after recursive read locks added into the graph.
8. Make __bfs(.math) return bool.
9-11 Adjust check_redundant(), check_noncircular() and
check_irq_usage() with recursive read locks into consideration.
12. Finally add recursive read locks into the dependency graph.
13-14 Adjust lock cache chain key generation with recursive read locks
into consideration, and provide a test case.
15-16 Add more test cases.
17. Revert commit d82fed752942 ("locking/lockdep/selftests: Fix
mixed read-write ABBA tests"),
18-19 Add more test cases (including tests that are specific for
queued_read_lock())
This series passed all the lockdep selftest cases (including those I
introduce).
Test and comments are welcome!
Regards,
Boqun
next reply other threads:[~2020-08-07 7:42 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-07 7:42 Boqun Feng [this message]
2020-08-07 7:42 ` [RFC v7 01/19] locking: More accurate annotations for read_lock() Boqun Feng
2020-08-07 7:42 ` [RFC v7 02/19] lockdep/Documention: Recursive read lock detection reasoning Boqun Feng
2020-08-07 7:42 ` [RFC v7 03/19] lockdep: Demagic the return value of BFS Boqun Feng
2020-08-07 7:42 ` [RFC v7 04/19] lockdep: Make __bfs() visit every dependency until a match Boqun Feng
2020-08-07 7:42 ` [RFC v7 05/19] lockdep: Reduce the size of lock_list::distance Boqun Feng
2020-08-07 7:42 ` [RFC v7 06/19] lockdep: Introduce lock_list::dep Boqun Feng
2020-08-07 7:42 ` [RFC v7 07/19] lockdep: Extend __bfs() to work with multiple types of dependencies Boqun Feng
2020-08-07 7:42 ` [RFC v7 08/19] lockdep: Make __bfs(.match) return bool Boqun Feng
2020-08-07 7:42 ` [RFC v7 09/19] lockdep: Support deadlock detection for recursive read locks in check_noncircular() Boqun Feng
2020-08-07 7:42 ` [RFC v7 10/19] lockdep: Adjust check_redundant() for recursive read change Boqun Feng
2020-08-07 7:42 ` [RFC v7 11/19] lockdep: Fix recursive read lock related safe->unsafe detection Boqun Feng
2020-09-15 18:32 ` Qian Cai
2020-09-16 8:10 ` Boqun Feng
2020-09-16 16:14 ` Boqun Feng
2020-09-16 21:11 ` Qian Cai
2020-09-17 1:53 ` Boqun Feng
2020-08-07 7:42 ` [RFC v7 12/19] lockdep: Add recursive read locks into dependency graph Boqun Feng
2020-09-14 18:16 ` Qian Cai
2020-09-14 22:04 ` Qian Cai
2020-08-07 7:42 ` [RFC v7 13/19] lockdep/selftest: Add a R-L/L-W test case specific to chain cache behavior Boqun Feng
2020-08-07 7:42 ` [RFC v7 14/19] lockdep: Take read/write status in consideration when generate chainkey Boqun Feng
2020-08-21 17:41 ` Peter Zijlstra
2020-08-22 2:52 ` boqun.feng
2020-08-07 7:42 ` [RFC v7 15/19] lockdep/selftest: Unleash irq_read_recursion2 and add more Boqun Feng
2020-08-07 7:42 ` [RFC v7 16/19] lockdep/selftest: Add more recursive read related test cases Boqun Feng
2020-08-07 7:42 ` [RFC v7 17/19] Revert "locking/lockdep/selftests: Fix mixed read-write ABBA tests" Boqun Feng
2020-08-07 7:42 ` [RFC v7 18/19] locking/selftest: Add test cases for queued_read_lock() Boqun Feng
2020-08-07 7:42 ` [RFC v7 19/19] lockdep/selftest: Introduce recursion3 Boqun Feng
2020-08-21 19:56 ` [RFC v7 00/19] lockdep: Support deadlock detection for recursive read locks Peter Zijlstra
2020-08-23 1:12 ` boqun.feng
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