From: Michel Lespinasse <walken@google.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Laurent Dufour <ldufour@linux.ibm.com>,
Liam Howlett <Liam.Howlett@oracle.com>,
Jerome Glisse <jglisse@redhat.com>,
Davidlohr Bueso <dave@stgolabs.net>,
David Rientjes <rientjes@google.com>,
Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [PATCH v5.5 09/10] mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()
Date: Tue, 19 May 2020 06:06:14 -0700 [thread overview]
Message-ID: <20200519130614.GC189720@google.com> (raw)
In-Reply-To: <fcf53ca7-d3a0-93e2-47af-7dd9b32b081a@suse.cz>
On Mon, May 18, 2020 at 01:01:33PM +0200, Vlastimil Babka wrote:
> On 4/24/20 3:38 AM, Michel Lespinasse wrote:
> > +static inline void mmap_assert_locked(struct mm_struct *mm)
> > +{
> > + VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_sem, -1), mm);
> > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> > +}
> > +
> > +static inline void mmap_assert_write_locked(struct mm_struct *mm)
> > +{
> > + VM_BUG_ON_MM(!lockdep_is_held_type(&mm->mmap_sem, 0), mm);
> > + VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
> > +}
>
> I would remove VM_BUG_ON_MM() from the lockdep part. If kernel has lockdep
> enabled, it's already in heavy debugging mode enough so let's just use it and
> not depend on DEBUG_VM. Many sites you convert don't require DEBUG_VM for the
> lockdep checks.
>
> With that you can also use the standard lockdep_assert_held() and
> lockdep_assert_held_write() wrappers.
>
> If user has both lockdep and DEBUG_VM enabled, should we run both variants?
> Perhaps lockdep is enough as it's more comprehensive? Your initial v5 version
> was doing that.
Thanks, changed these to lockdep_assert_held() /
lockdep_assert_held_write() as suggested. This misses dumping out the
mm, but I think there is only limited value in that. I did keep the
rwsem_is_locked fallback as people had commented earlier about
getting assertions in the non-lockdep case. If both are enabled...
then we'll get somewhat redundant assertions, but I think that is fine
(better to keep the code simple than try to work around that).
--
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
next prev parent reply other threads:[~2020-05-19 13:06 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 0:14 [PATCH v5 00/10] Add a new mmap locking API wrapping mmap_sem calls Michel Lespinasse
2020-04-22 0:14 ` [PATCH v5 01/10] mmap locking API: initial implementation as rwsem wrappers Michel Lespinasse
2020-05-18 9:28 ` Vlastimil Babka
2020-05-18 13:18 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 02/10] MMU notifier: use the new mmap locking API Michel Lespinasse
2020-05-18 9:28 ` Vlastimil Babka
2020-05-18 13:19 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 03/10] DMA reservations: " Michel Lespinasse
2020-05-18 9:30 ` Vlastimil Babka
2020-05-18 13:20 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 04/10] mmap locking API: use coccinelle to convert mmap_sem rwsem call sites Michel Lespinasse
2020-05-18 9:36 ` Vlastimil Babka
2020-05-18 13:21 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 05/10] mmap locking API: convert mmap_sem call sites missed by coccinelle Michel Lespinasse
2020-05-18 9:44 ` Vlastimil Babka
2020-05-18 13:23 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 06/10] mmap locking API: convert nested write lock sites Michel Lespinasse
2020-05-18 10:32 ` Vlastimil Babka
2020-05-19 12:54 ` Michel Lespinasse
2020-05-18 13:24 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 07/10] mmap locking API: add mmap_read_trylock_non_owner() Michel Lespinasse
2020-05-18 10:42 ` Vlastimil Babka
2020-04-22 0:14 ` [PATCH v5 08/10] mmap locking API: add MMAP_LOCK_INITIALIZER Michel Lespinasse
2020-05-18 10:45 ` Vlastimil Babka
2020-05-19 12:56 ` Michel Lespinasse
2020-05-18 13:33 ` Laurent Dufour
2020-04-22 0:14 ` [PATCH v5 09/10] mmap locking API: add mmap_assert_locked Michel Lespinasse
2020-04-22 2:10 ` Michel Lespinasse
2020-04-22 2:18 ` Matthew Wilcox
2020-04-24 1:44 ` Michel Lespinasse
2020-04-22 0:14 ` [PATCH v5 10/10] mmap locking API: rename mmap_sem to mmap_lock Michel Lespinasse
2020-04-22 1:58 ` Matthew Wilcox
2020-04-22 22:54 ` Michel Lespinasse
2020-04-23 1:59 ` Matthew Wilcox
2020-04-24 1:26 ` Michel Lespinasse
2020-04-24 1:38 ` [PATCH v5.5 09/10] mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked() Michel Lespinasse
2020-05-18 11:01 ` Vlastimil Babka
2020-05-19 13:06 ` Michel Lespinasse [this message]
2020-04-24 1:39 ` [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock Michel Lespinasse
2020-05-18 11:07 ` Vlastimil Babka
2020-05-19 13:12 ` Michel Lespinasse
2020-05-18 13:45 ` Laurent Dufour
2020-05-19 13:10 ` Michel Lespinasse
2020-05-19 13:20 ` Laurent Dufour
2020-05-19 15:32 ` Matthew Wilcox
2020-05-19 18:14 ` John Hubbard
2020-05-20 2:39 ` Michel Lespinasse
2020-05-20 7:32 ` John Hubbard
2020-05-20 8:02 ` Michel Lespinasse
2020-05-20 12:48 ` Jason Gunthorpe
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