linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com,
	linux-ide@vger.kernel.org, adilger.kernel@dilger.ca,
	linux-ext4@vger.kernel.org, mingo@redhat.com,
	linux-kernel@vger.kernel.org, peterz@infradead.org,
	will@kernel.org, tglx@linutronix.de, joel@joelfernandes.org,
	sashal@kernel.org, daniel.vetter@ffwll.ch,
	chris@chris-wilson.co.uk, duyuyang@gmail.com,
	johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu,
	willy@infradead.org, david@fromorbit.com, amir73il@gmail.com,
	gregkh@linuxfoundation.org, kernel-team@lge.com,
	linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org,
	minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com,
	sj@kernel.org, jglisse@redhat.com, dennis@kernel.org,
	cl@linux.com, penberg@kernel.org, rientjes@google.com,
	vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org,
	paolo.valente@linaro.org, josef@toxicpanda.com,
	linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk,
	jack@suse.cz, jack@suse.com, jlayton@kernel.org,
	dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org,
	dri-devel@lists.freedesktop.org, airlied@linux.ie,
	rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com,
	hamohammed.sa@gmail.com
Subject: Re: [PATCH RFC v6 00/21] DEPT(Dependency Tracker)
Date: Mon, 9 May 2022 16:47:12 -0400	[thread overview]
Message-ID: <20220509164712.746e236b@gandalf.local.home> (raw)
In-Reply-To: <20220509001637.GA6047@X58A-UD3R>

On Mon, 9 May 2022 09:16:37 +0900
Byungchul Park <byungchul.park@lge.com> wrote:

> CASE 2.
> 
>    lock L with depth n
>    lock A
>    lock_nested L' with depth n + 1
>    ...
>    unlock L'
>    unlock A
>    unlock L
> 
> This case is allowed by Lockdep.
> This case is *NOT* allowed by DEPT cuz it's a *DEADLOCK*.
> 
> ---
> 
> The following scenario would explain why CASE 2 is problematic.
> 
>    THREAD X			THREAD Y
> 
>    lock L with depth n
> 				lock L' with depth n
>    lock A
> 				lock A
>    lock_nested L' with depth n + 1

I'm confused by what exactly you are saying is a deadlock above.

Are you saying that lock A and L' are inversed? If so, lockdep had better
detect that regardless of L. A nested lock associates the the nesting with
the same type of lock. That is, in lockdep nested tells lockdep not to
trigger on the L and L' but it will not ignore that A was taken.

-- Steve



> 				lock_nested L'' with depth n + 1
>    ...				...
>    unlock L'			unlock L''
>    unlock A			unlock A
>    unlock L			unlock L'


  reply	other threads:[~2022-05-09 20:47 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-04  8:17 [PATCH RFC v6 00/21] DEPT(Dependency Tracker) Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 01/21] llist: Move llist_{head,node} definition to types.h Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 02/21] dept: Implement Dept(Dependency Tracker) Byungchul Park
2022-05-21  3:24   ` Hyeonggon Yoo
2022-05-04  8:17 ` [PATCH RFC v6 03/21] dept: Apply Dept to spinlock Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 04/21] dept: Apply Dept to mutex families Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 05/21] dept: Apply Dept to rwlock Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 06/21] dept: Apply Dept to wait_for_completion()/complete() Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 07/21] dept: Apply Dept to seqlock Byungchul Park
2022-05-21  5:25   ` Hyeonggon Yoo
2022-05-24  6:00     ` Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 08/21] dept: Apply Dept to rwsem Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 09/21] dept: Add proc knobs to show stats and dependency graph Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 10/21] dept: Introduce split map concept and new APIs for them Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 11/21] dept: Apply Dept to wait/event of PG_{locked,writeback} Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 12/21] dept: Apply SDT to swait Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 13/21] dept: Apply SDT to wait(waitqueue) Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 14/21] locking/lockdep, cpu/hotplus: Use a weaker annotation in AP thread Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 15/21] dept: Distinguish each syscall context from another Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 16/21] dept: Distinguish each work " Byungchul Park
2022-05-04 11:23   ` Sergey Shtylyov
2022-05-04  8:17 ` [PATCH RFC v6 17/21] dept: Disable Dept within the wait_bit layer by default Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 18/21] dept: Disable Dept on struct crypto_larval's completion for now Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 19/21] dept: Differentiate onstack maps from others of different tasks in class Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 20/21] dept: Do not add dependencies between events within scheduler and sleeps Byungchul Park
2022-05-04  8:17 ` [PATCH RFC v6 21/21] dept: Unstage wait when tagging a normal sleep wait Byungchul Park
2022-05-04 18:17 ` [PATCH RFC v6 00/21] DEPT(Dependency Tracker) Linus Torvalds
2022-05-06  0:11   ` Byungchul Park
2022-05-07  7:20     ` Hyeonggon Yoo
2022-05-09  0:16       ` Byungchul Park
2022-05-09 20:47         ` Steven Rostedt [this message]
2022-05-09 23:38           ` Byungchul Park
2022-05-10 14:12             ` Steven Rostedt
2022-05-10 23:26               ` Byungchul Park
2022-05-10 11:18         ` Hyeonggon Yoo
2022-05-10 23:39           ` Byungchul Park
2022-05-11 10:04             ` Hyeonggon Yoo
2022-05-19 10:11               ` Catalin Marinas
2022-05-23  2:43                 ` Byungchul Park
2022-05-09  1:22   ` Byungchul Park
2022-05-09 21:05 ` Theodore Ts'o
2022-05-09 22:28   ` Theodore Ts'o
2022-05-10  0:32     ` Byungchul Park
2022-05-10  1:32       ` Theodore Ts'o
2022-05-10  5:37         ` Byungchul Park
2022-05-11  1:16           ` Byungchul Park
2022-05-12  5:25 ` [REPORT] syscall reboot + umh + firmware fallback Byungchul Park
2022-05-12  9:15   ` Tejun Heo
2022-05-12 11:18     ` Byungchul Park
2022-05-12 13:56       ` Theodore Ts'o
2022-05-23  1:10         ` Byungchul Park
2022-05-12 16:41       ` Tejun Heo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220509164712.746e236b@gandalf.local.home \
    --to=rostedt@goodmis.org \
    --cc=42.hyeyoo@gmail.com \
    --cc=adilger.kernel@dilger.ca \
    --cc=airlied@linux.ie \
    --cc=akpm@linux-foundation.org \
    --cc=amir73il@gmail.com \
    --cc=byungchul.park@lge.com \
    --cc=chris@chris-wilson.co.uk \
    --cc=cl@linux.com \
    --cc=damien.lemoal@opensource.wdc.com \
    --cc=dan.j.williams@intel.com \
    --cc=daniel.vetter@ffwll.ch \
    --cc=david@fromorbit.com \
    --cc=dennis@kernel.org \
    --cc=djwong@kernel.org \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=duyuyang@gmail.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hamohammed.sa@gmail.com \
    --cc=hannes@cmpxchg.org \
    --cc=hch@infradead.org \
    --cc=jack@suse.com \
    --cc=jack@suse.cz \
    --cc=jglisse@redhat.com \
    --cc=jlayton@kernel.org \
    --cc=joel@joelfernandes.org \
    --cc=johannes.berg@intel.com \
    --cc=josef@toxicpanda.com \
    --cc=kernel-team@lge.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-ide@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=melissa.srw@gmail.com \
    --cc=mhocko@kernel.org \
    --cc=minchan@kernel.org \
    --cc=mingo@redhat.com \
    --cc=ngupta@vflare.org \
    --cc=paolo.valente@linaro.org \
    --cc=penberg@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rientjes@google.com \
    --cc=rodrigosiqueiramelo@gmail.com \
    --cc=sashal@kernel.org \
    --cc=sj@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tj@kernel.org \
    --cc=torvalds@linux-foundation.org \
    --cc=tytso@mit.edu \
    --cc=vbabka@suse.cz \
    --cc=vdavydov.dev@gmail.com \
    --cc=viro@zeniv.linux.org.uk \
    --cc=will@kernel.org \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).