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From: Matthew Wilcox <willy@infradead.org>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	linux-mm@kvack.org, hch@lst.de, jszhang@marvell.com,
	joelaf@google.com, chris@chris-wilson.co.uk, joaodias@google.com,
	tglx@linutronix.de, hpa@zytor.com, mingo@elte.hu,
	Thomas Hellstrom <thellstrom@vmware.com>,
	dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>
Subject: Re: [PATCH] mm: Remove pointless might_sleep() in remove_vm_area().
Date: Mon, 27 Mar 2017 07:06:10 -0700	[thread overview]
Message-ID: <20170327140610.GA27285@bombadil.infradead.org> (raw)
In-Reply-To: <0eceef23-a20c-bca7-2153-b9b5baf1f1d8@virtuozzo.com>

On Mon, Mar 27, 2017 at 04:26:02PM +0300, Andrey Ryabinin wrote:
> [+CC drm folks, see the following threads:
> 	http://lkml.kernel.org/r/201703232349.BGB95898.QHLVFFOMtFOOJS@I-love.SAKURA.ne.jp
> 	http://lkml.kernel.org/r/1490352808-7187-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
> ]
> 
> On 03/24/2017 07:17 PM, Matthew Wilcox wrote:
> > On Fri, Mar 24, 2017 at 06:05:45PM +0300, Andrey Ryabinin wrote:
> >> Just fix the drm code. There is zero point in releasing memory under spinlock.
> > 
> > I disagree.  The spinlock has to be held while deleting from the hash
> > table. 
> 
> And what makes you think so?

The bad naming of the function.  If somebody has a function called
'hashtable_remove' I naturally think it means "remove something from
the hash table".  This function should be called drm_ht_destroy().
And then, yes, it becomes obvious that there is no need to protect
destuction against usage because if anyone is still using the hashtable,
they're about to get a NULL pointer dereference.

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  reply	other threads:[~2017-03-27 14:06 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-24 10:53 Tetsuo Handa
2017-03-24 12:22 ` Andrey Ryabinin
2017-03-24 12:40   ` Tetsuo Handa
2017-03-24 15:05     ` Andrey Ryabinin
2017-03-24 16:17       ` Matthew Wilcox
2017-03-27 13:26         ` Andrey Ryabinin
2017-03-27 14:06           ` Matthew Wilcox [this message]
2017-03-27 14:10           ` Thomas Hellstrom
2017-03-27 14:29             ` Tetsuo Handa
2017-03-27 15:02               ` Andrey Ryabinin
2017-03-28 10:07                 ` Tetsuo Handa
2017-03-24 22:47       ` Tetsuo Handa
2017-03-27 10:16         ` Tetsuo Handa

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