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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nikolay Borisov <nborisov@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Khazhismel Kumykov <khazhy@google.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	David Rientjes <rientjes@google.com>,
	Goldwyn Rodrigues <rgoldwyn@suse.de>,
	Jeff Mahoney <jeffm@suse.com>,
	Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [PATCH] fs/dcache.c: re-add cond_resched() in shrink_dcache_parent()
Date: Sun, 15 Apr 2018 01:51:07 +0100	[thread overview]
Message-ID: <20180415005056.GX30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFxD1xKqbobvoHQUWc5jc9n7-7KXYeSQy-CpE0SUZHi0PQ@mail.gmail.com>

On Sat, Apr 14, 2018 at 02:47:21PM -0700, Linus Torvalds wrote:
> On Sat, Apr 14, 2018 at 1:58 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > That breaks d_invalidate(), unfortunately.  Look at the termination
> > conditions in the loop there...
> 
> Ugh. I was going to say "but that doesn't even use select_collect()",
> but yeah, detach_and_collect() calls it.
> 
> It would be easy enough to just change the
> 
>                 if (!list_empty(&data.select.dispose))
> 
> there to
> 
>                 if (!list_empty(&data.select.found))
> 
> too.

You would have to do the same in check_and_drop() as well,
and that brings back d_invalidate()/d_invalidate() livelock
we used to have.  See 81be24d263db...

I'm trying to put something together, but the damn thing is
full of potential livelocks, unfortunately ;-/  Will send
a followup once I have something resembling a sane solution...

  reply	other threads:[~2018-04-15  0:51 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20180413181350.88831-1-khazhy@google.com>
2018-04-13 20:28 ` [PATCH] fs/dcache.c: re-add cond_resched() in shrink_dcache_parent() Khazhismel Kumykov
2018-04-13 21:14   ` Andrew Morton
2018-04-14  7:00     ` Nikolay Borisov
2018-04-14  8:02       ` Al Viro
2018-04-14 16:36         ` Linus Torvalds
2018-04-14 20:58           ` Al Viro
2018-04-14 21:47             ` Linus Torvalds
2018-04-15  0:51               ` Al Viro [this message]
2018-04-15  2:39                 ` Al Viro
2018-04-15 14:21                   ` Al Viro
2018-04-15 18:34                 ` Linus Torvalds
2018-04-15 20:40                   ` Al Viro
2018-04-15 21:54                     ` Al Viro
2018-04-15 22:34                       ` Al Viro
2018-04-16 18:28                         ` Khazhismel Kumykov
2018-04-13 21:15   ` David Rientjes

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