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From: "bfields@fieldses.org" <bfields@fieldses.org>
To: Trond Myklebust <trondmy@hammerspace.com>
Cc: "olivier@bm-services.com" <olivier@bm-services.com>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"carnil@debian.org" <carnil@debian.org>,
	"chuck.lever@oracle.com" <chuck.lever@oracle.com>
Subject: Re: Kernel panic / list_add corruption when in nfsd4_run_cb_work
Date: Wed, 24 Nov 2021 17:06:41 -0500	[thread overview]
Message-ID: <20211124220640.GE30602@fieldses.org> (raw)
In-Reply-To: <e17bbb0a22b154c77c6ec82aad63424f70bfda94.camel@hammerspace.com>

On Wed, Nov 24, 2021 at 05:14:53PM +0000, Trond Myklebust wrote:
> It is a little nasty that we hide the list_del() calls in several
> levels of function call, so they probably do deserve a comment.
> 
> That said, if, as in the case here, the delegation was unhashed, we
> still end up not calling list_del_init() in unhash_delegation_locked(),
> and since the list_add() is not conditional on it being successful, the
> global list is again corrupted.
> 
> Yes, it is an unlikely race, but it is possible despite your change.

Thanks, good point.

Probably not something anyone's actually hitting, but another sign this
logic need rethinking.

--b.

  reply	other threads:[~2021-11-24 22:06 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-11  7:59 Kernel panic / list_add corruption when in nfsd4_run_cb_work Salvatore Bonaccorso
2020-10-12 14:26 ` J. Bruce Fields
2020-10-12 15:41   ` Salvatore Bonaccorso
2020-10-12 16:33     ` J. Bruce Fields
2020-10-18  9:39       ` Salvatore Bonaccorso
2021-10-06 18:46         ` Salvatore Bonaccorso
2021-11-22  9:15           ` Olivier Monaco
2021-11-22 15:17             ` Chuck Lever III
2021-11-24 15:29               ` Bruce Fields
2021-11-24 15:59                 ` Trond Myklebust
2021-11-24 16:10                   ` Trond Myklebust
2021-11-24 16:10                   ` bfields
2021-11-24 17:14                     ` Trond Myklebust
2021-11-24 22:06                       ` bfields [this message]
2021-11-24 22:17                         ` Trond Myklebust
2021-12-01 22:33                           ` bfields

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