From: Oleg Nesterov <oleg@tv-sign.ru>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Marc Dietrich <Marc.Dietrich@ap.physik.uni-giessen.de>,
Johannes Berg <johannes@sipsolutions.net>,
nfs@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [NFS] 2.6.23-rc1-mm2
Date: Wed, 8 Aug 2007 03:14:37 +0400 [thread overview]
Message-ID: <20070807231437.GA1004@tv-sign.ru> (raw)
In-Reply-To: <1186528107.6625.71.camel@heimdal.trondhjem.org>
On 08/07, Trond Myklebust wrote:
>
> On Wed, 2007-08-08 at 02:20 +0400, Oleg Nesterov wrote:
>
> > But. nfs4_renew_state() checks list_empty(&clp->cl_superblocks) under
> > clp->cl_sem? So, if it is possible that clp->cl_renewd was scheduled
> > at the time when nfs4_kill_renewd(), we can deadlock, no? Because
> > nfs4_renew_state() needs clp->cl_sem to complete, but nfs4_kill_renewd()
> > holds this sem, and waits for nfs4_renew_state() completion.
>
> They both take read locks,
Aaaaaaaaaah. Please ignore me, thanks!
> which means that they can take them
> simultaneously. AFAICS, the deadlock can only occur if something manages
> to insert a request for a write lock after nfs4_kill_renewd() takes its
> read lock, but before nfs4_renew_state() takes its read lock:
>
> 1) nfs4_kill_renewd() 2) nfs4_renew_state() 3) somebody else
> ------------------- ------------------ -------------
> read lock
> wait on (2) to complete
> write lock <waits on (1)>
> read lock <waits on (3),
> because rw_semaphores
> don't allow a read lock
> request to jump a write
> lock request>
>
> however as I explained earlier, the only process that can take a write
> lock is the reclaimer daemon, but we _know_ that cannot be running (for
> one thing, the reference count on nfs_client is zero, for the other,
> there are no superblocks).
Oleg.
next prev parent reply other threads:[~2007-08-07 23:14 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-01 6:09 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 6:25 ` 2.6.23-rc1-mm2 Paul Mundt
2007-08-01 7:58 ` 2.6.23-rc1-mm2 Mike Frysinger
2007-08-01 8:10 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 13:45 ` 2.6.23-rc1-mm2 Christoph Hellwig
2007-08-01 13:57 ` 2.6.23-rc1-mm2 Jason Wessel
2007-08-01 8:15 ` 2.6.23-rc1-mm2 Paul Mundt
2007-08-01 9:04 ` 2.6.23-rc1-mm2 Mike Frysinger
2007-08-01 12:22 ` 2.6.23-rc1-mm2 Jason Wessel
2007-08-01 7:36 ` 2.6.23-rc1-mm2 (vm-dont-run-touch_buffer-during-buffercache-lookups.patch) Eric St-Laurent
2007-08-01 7:46 ` Andrew Morton
2007-08-01 8:04 ` Eric St-Laurent
2007-08-01 8:30 ` Andrew Morton
2007-08-01 8:02 ` 2.6.23-rc1-mm2 Mariusz Kozlowski
2007-08-01 8:13 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 8:16 ` 2.6.23-rc1-mm2 Ingo Molnar
2007-08-01 10:23 ` 2.6.23-rc1-mm2 Jiri Kosina
2007-08-02 9:47 ` 2.6.23-rc1-mm2 Mariusz Kozlowski
2007-08-02 14:20 ` [linux-usb-devel] 2.6.23-rc1-mm2 Alan Stern
2007-08-02 14:26 ` Jiri Kosina
2007-08-02 14:32 ` Mariusz Kozlowski
2007-08-01 10:32 ` 2.6.23-rc1-mm2 Paul Mackerras
2007-08-02 10:14 ` 2.6.23-rc1-mm2 Mariusz Kozlowski
2007-08-03 9:39 ` 2.6.23-rc1-mm2 Kumar Gala
2007-08-06 19:12 ` 2.6.23-rc1-mm2 Segher Boessenkool
2007-08-06 19:10 ` 2.6.23-rc1-mm2 Segher Boessenkool
2007-08-01 16:36 ` 2.6.23-rc1-mm2 Greg KH
2007-08-06 19:08 ` 2.6.23-rc1-mm2 Segher Boessenkool
2007-08-06 19:34 ` 2.6.23-rc1-mm2 Mariusz Kozlowski
2007-08-06 21:25 ` 2.6.23-rc1-mm2 Segher Boessenkool
2007-08-06 22:34 ` 2.6.23-rc1-mm2 Mariusz Kozlowski
2007-08-06 23:12 ` 2.6.23-rc1-mm2 Segher Boessenkool
2007-08-01 9:34 ` [PATCH] prevent SSB compilation on s390 part 2 Heiko Carstens
2007-08-01 12:24 ` John W. Linville
2007-08-01 14:43 ` Heiko Carstens
2007-08-01 14:54 ` Michael Buesch
2007-08-01 10:33 ` unionfs compile error ( Re: 2.6.23-rc1-mm2 ) Gabriel C
2007-08-01 17:22 ` Andrew Morton
2007-08-01 17:27 ` Josef Sipek
2007-08-02 16:29 ` Erez Zadok
2007-08-01 17:35 ` Gabriel C
2007-08-01 10:56 ` 2.6.23-rc1-mm2 Gabriel C
2007-08-01 17:26 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 17:39 ` 2.6.23-rc1-mm2 Gabriel C
2007-08-01 11:16 ` [PATCH] fix slown down printk on boot compile error Heiko Carstens
2007-08-01 16:32 ` Randy Dunlap
2007-08-01 13:01 ` drivers/scsi/advansys.c compile error ( Re: 2.6.23-rc1-mm2 ) Gabriel C
2007-08-01 13:39 ` [PATCH] drivers/scsi/advansys.c: fix advansys_board_found compile error Eugene Teo
2007-08-01 13:54 ` Gabriel C
2007-08-01 13:55 ` Matthew Wilcox
2007-08-01 14:27 ` Gabriel C
2007-08-01 14:32 ` Matthew Wilcox
2007-08-01 14:46 ` Gabriel C
2007-08-01 14:23 ` [PATCH -mm] Fix defined but not used warning in drivers/kvm/vmx.c Gabriel C
2007-08-01 18:35 ` Avi Kivity
2007-08-01 15:19 ` [PATCH -mm] Fix a section mismatch warning Gabriel C
2007-08-01 20:13 ` 2.6.23-rc1-mm2 (checks-for-80wire-cable-use-in-pata_via) Laurent Riffard
2007-08-01 20:30 ` 2.6.23-rc1-mm2 Valdis.Kletnieks
2007-08-01 20:40 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 20:52 ` 2.6.23-rc1-mm2 Torsten Kaiser
2007-08-01 21:17 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-01 23:40 ` 2.6.23-rc1-mm2 Mel Gorman
2007-08-02 4:38 ` 2.6.23-rc1-mm2 Torsten Kaiser
2007-08-02 14:01 ` 2.6.23-rc1-mm2 Andy Whitcroft
2007-08-02 17:44 ` 2.6.23-rc1-mm2 Torsten Kaiser
2007-08-01 23:40 ` INOTIFY=n , AUDIT*=y compile error Gabriel C
2007-08-01 23:59 ` [PATCH -mm] linux-audit list is subscribers-only Gabriel C
2007-08-02 1:30 ` Randy Dunlap
2007-08-02 13:11 ` [PATCH -mm] Fix section mismatch warnings in sound/pci/hda/ Gabriel C
2007-08-02 13:24 ` Takashi Iwai
2007-08-02 16:32 ` Sam Ravnborg
2007-08-02 17:17 ` Takashi Iwai
2007-08-02 17:31 ` 2.6.23-rc1-mm2: Fix crash in sysfs_hash_and_remove Rafael J. Wysocki
2007-08-02 17:34 ` Tejun Heo
2007-08-02 18:19 ` Eric W. Biederman
2007-08-03 11:00 ` 2.6.23-rc1-mm2 Marc Dietrich
2007-08-03 16:38 ` 2.6.23-rc1-mm2 Andrew Morton
2007-08-03 17:03 ` [NFS] 2.6.23-rc1-mm2 Trond Myklebust
2007-08-03 17:21 ` Oleg Nesterov
2007-08-06 6:24 ` Johannes Berg
2007-08-06 10:53 ` Oleg Nesterov
2007-08-06 10:58 ` Johannes Berg
2007-08-06 11:05 ` Marc Dietrich
2007-08-06 11:13 ` Johannes Berg
2007-08-06 16:24 ` Trond Myklebust
2007-08-07 12:09 ` Marc Dietrich
2007-08-07 21:08 ` Trond Myklebust
2007-08-07 21:37 ` Oleg Nesterov
2007-08-07 22:05 ` Trond Myklebust
2007-08-07 22:20 ` Oleg Nesterov
2007-08-07 23:08 ` Trond Myklebust
2007-08-07 23:14 ` Oleg Nesterov [this message]
2007-08-08 21:31 ` 2.6.23-rc1-mm2: MMC_ARMMMCI compile error Adrian Bunk
2007-08-09 12:03 ` Pierre Ossman
2007-08-14 21:21 ` [-mm patch] make pm3fb_init() static again Adrian Bunk
2007-08-14 21:21 ` [-mm patch] fs/reiser4/plugin/: make 3 functions static Adrian Bunk
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