From: NeilBrown <neilb@suse.com>
To: Joel Fernandes <joelaf@google.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>,
Minchan Kim <minchan@kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Theodore Ts'o <tytso@mit.edu>,
linux-fsdevel@vger.kernel.org, Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH RFC] ashmem: Fix lockdep RECLAIM_FS false positive
Date: Thu, 08 Feb 2018 11:35:43 +1100 [thread overview]
Message-ID: <87k1vomi74.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <CAJWu+opo+mE-ZAsi3=u8ogUYurVM0_qaHi7keZJ6h0Sfa7oULQ@mail.gmail.com>
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On Wed, Feb 07 2018, Joel Fernandes wrote:
> Hi Peter,
>
> On Wed, Feb 7, 2018 at 8:58 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> [...]
>>
>>> Lockdep reports this issue when GFP_FS is infact set, and we enter
>>> this path and acquire the lock. So lockdep seems to be doing the right
>>> thing however by design it is reporting a false-positive.
>>
>> So I'm not seeing how its a false positive. fs/inode.c sets a different
>> lock class per filesystem type. So recursing on an i_mutex within a
>> filesystem does sound dodgy.
>
> But directory inodes and file inodes in the same filesystem share the
> same lock class right?
Not since v2.6.24
Commit: 14358e6ddaed ("lockdep: annotate dir vs file i_mutex")
You were using 4.9.60. so they should be separate....
Maybe shmem_get_inode() needs to call unlock_new_inode() or just
lockdep_annotate_inode_mutex_key() after inode_init_owner().
Maybe inode_init_owner() should call lockdep_annotate_inode_mutex_key()
directly.
NeilBrown
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next prev parent reply other threads:[~2018-02-08 0:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-06 0:49 Joel Fernandes
2018-02-06 22:01 ` Minchan Kim
2018-02-06 22:32 ` Joel Fernandes
2018-02-06 22:55 ` Minchan Kim
2018-02-06 23:16 ` Joel Fernandes
2018-02-07 8:07 ` Peter Zijlstra
2018-02-07 16:09 ` Joel Fernandes
2018-02-07 16:58 ` Peter Zijlstra
2018-02-07 22:27 ` Joel Fernandes
2018-02-08 0:35 ` NeilBrown [this message]
2018-02-08 2:29 ` Joel Fernandes
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