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From: Peter Zijlstra <peterz@infradead.org>
To: Schspa Shi <schspa@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Ingo Molnar <mingo@kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	syzkaller-bugs@googlegroups.com,
	syzbot <syzbot+6cd18e123583550cf469@syzkaller.appspotmail.com>,
	Hillf Danton <hdanton@sina.com>
Subject: Re: [syzbot] WARNING: locking bug in umh_complete
Date: Wed, 22 Feb 2023 10:34:42 +0100	[thread overview]
Message-ID: <Y/Xhsna3gfadzAAk@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <m21qmkahoj.fsf@gmail.com>

On Tue, Feb 14, 2023 at 10:31:58AM +0800, Schspa Shi wrote:
> Peter Zijlstra <peterz@infradead.org> writes:

> > If so, perhaps the simplest rule would to be ensure there is an
> > unconditional uninterruptible wait-for-completion() before going out of
> > scope.
> >
> > This latter can be spelled like wait_for_completion() or
> > wait_for_completion_state(TASK_UNINTERRUPTIBLE). More specifically,
> > TASK_INTERRUPTIBLE and TASK_WAKEKILL must not be set in the state mask
> > for the wait to be uninterruptible.
> >
> > If it cannot be proven, raise a warning and audit or somesuch.
> 
> This is a good suggestion. I have written a SmPL patch to complete this
> check, and now I need to rule out the situation that the driver has
> added an additional lock to protect it.
> 
> And I have found a lot of bad usage, should we consider adding a new
> helper API to simplify the fix this?

Please first share some of the locations where this would be applied.

  parent reply	other threads:[~2023-02-22  9:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230127014137.4906-1-hdanton@sina.com>
2023-02-03 10:22 ` Tetsuo Handa
2023-02-03 10:48   ` Tetsuo Handa
2023-02-03 12:19     ` Peter Zijlstra
2023-02-03 12:30       ` Peter Zijlstra
2023-02-03 12:59         ` Tetsuo Handa
2023-02-03 14:31           ` Peter Zijlstra
2023-02-04  0:48             ` Tetsuo Handa
2023-02-06 15:51               ` Luis Chamberlain
2023-02-13 15:14                 ` Peter Zijlstra
2023-02-13 15:27                 ` Peter Zijlstra
2023-02-14  2:31                   ` Schspa Shi
2023-02-21 21:54                     ` Luis Chamberlain
2023-02-22  9:34                     ` Peter Zijlstra [this message]
2023-02-27  7:57                       ` Schspa Shi
2023-02-13 15:34               ` Peter Zijlstra
2023-02-14 11:16                 ` Tetsuo Handa
2023-02-15 10:33             ` [tip: sched/urgent] freezer,umh: Fix call_usermode_helper_exec() vs SIGKILL tip-bot2 for Peter Zijlstra
2023-02-03 12:00   ` [syzbot] WARNING: locking bug in umh_complete Peter Zijlstra
2023-01-26 22:27 syzbot

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