From: Andrea Arcangeli <andrea@suse.de>
To: Jari Ruusu <jari.ruusu@pp.inet.fi>
Cc: Jens Axboe <axboe@suse.de>,
Marcelo Tosatti <marcelo@conectiva.com.br>,
Herbert Valerio Riedel <hvr@hvrlab.org>,
linux-kernel@vger.kernel.org
Subject: Re: 2.4.19pre3aa2
Date: Sat, 16 Mar 2002 14:54:45 +0100 [thread overview]
Message-ID: <20020316145445.C15709@dualathlon.random> (raw)
In-Reply-To: <20020314032801.C1273@dualathlon.random> <3C912ACF.AF3EE6F0@pp.inet.fi> <20020315105621.GA22169@suse.de> <3C9230C6.4119CB4C@pp.inet.fi> <20020315185747.P10073@dualathlon.random> <3C933633.891663B0@pp.inet.fi>
In-Reply-To: <3C933633.891663B0@pp.inet.fi>
On Sat, Mar 16, 2002 at 02:10:27PM +0200, Jari Ruusu wrote:
> Andrea Arcangeli wrote:
> > Nevertheless as Jens said the infinite-loop-allocation in the
> > ->make_request_fn path are deadlock prone at the moment, not because
> > they sleeps but because they need a reserved mempool to guarantee
> > operations can go ahead slowly without deadlocks even if dynamic
> > allocation fails, but this is not a very pratical problem, it's very
> > unlikely to deadlock there (it's not worse than the other infinite loop
> > in getblk() that affects not just loop).
>
> Unlikely to deadlock for normal filesystems, but swap on encrypted loop is a
> different case.
Not really much different, it's no different than other paths like
getblk (when you swap on top of the fs) and brw_page (OTOH we have a
little reserved shared pool for the async bh needed by brw_page but it's not
math accurate first of all because it's shared for the other pagecache
I/O too), it just increases a little the mem pressure when there's
a transfer function involved and the translation cannot be done in
place, but I obviously agree that such loop deadlock needs fixing
reagardless if it's easy to reproduce it or not :). Infact I think I
mentioned such deadlock in the past too.
> Deadlock free operation is exactly why my prealloc loop patch is needed.
> Beyond initial preallocating that is done at losetup time, it does not
> allocate anything from kernel memory pools, but effectively recycles its
> private per loop device preallocated memory. Encrypted swap needs that, and
> normal device backed loop file systems are also happy with deadlock free and
> VM stress free operation.
Yes, thanks.
Andrea
next prev parent reply other threads:[~2002-03-16 13:54 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-03-14 2:28 2.4.19pre3aa2 Andrea Arcangeli
2002-03-14 12:32 ` 2.4.19pre3aa2 Dave Jones
2002-03-14 12:37 ` 2.4.19pre3aa2 Andrea Arcangeli
2002-03-14 12:46 ` 2.4.19pre3aa2 Jeff Garzik
2002-03-14 12:59 ` 2.4.19pre3aa2 Dave Jones
2002-03-14 15:53 ` 2.4.19pre3aa2 Bill Davidsen
2002-03-14 16:12 ` 2.4.19pre3aa2 Andrea Arcangeli
2002-03-14 16:16 ` 2.4.19pre3aa2 Dave Jones
2002-03-14 16:32 ` 2.4.19pre3aa2 Andrea Arcangeli
2002-03-16 1:26 ` 2.4.19pre3aa2 Mike Fedyk
2002-03-14 16:13 ` 2.4.19pre3aa2 Dave Jones
2002-03-14 17:16 ` 2.4.19pre3aa2 Bill Davidsen
2002-03-14 21:16 ` 2.4.19pre3aa2 H. Peter Anvin
2002-03-14 18:00 ` 2.4.19pre3aa2 Andrew Morton
2002-03-14 22:57 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-15 10:56 ` 2.4.19pre3aa2 Jens Axboe
2002-03-15 11:06 ` 2.4.19pre3aa2 Jens Axboe
2002-03-15 17:35 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-15 17:57 ` 2.4.19pre3aa2 Andrea Arcangeli
2002-03-16 12:10 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-16 13:54 ` Andrea Arcangeli [this message]
2002-03-18 19:13 ` 2.4.19pre3aa2 Jens Axboe
2002-03-19 23:26 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-20 7:54 ` 2.4.19pre3aa2 Jens Axboe
2002-03-20 18:16 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-20 14:21 ` 2.4.19pre3aa2 Herbert Valerio Riedel
2002-03-15 12:19 ` 2.4.19pre3aa2 Herbert Valerio Riedel
2002-03-15 17:36 ` 2.4.19pre3aa2 Jari Ruusu
2002-03-15 18:36 ` 2.4.19pre3aa2 Herbert Valerio Riedel
2002-03-16 12:12 ` 2.4.19pre3aa2 Jari Ruusu
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