From: "André Draszik" <andre.draszik@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-kernel@vger.kernel.org
Cc: "André Almeida" <andrealmeid@igalia.com>,
"Darren Hart" <dvhart@infradead.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"Ingo Molnar" <mingo@redhat.com>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Valentin Schneider" <vschneid@redhat.com>,
"Waiman Long" <longman@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Hildenbrand" <david@redhat.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
"Lorenzo Stoakes" <lorenzo.stoakes@oracle.com>,
"Michal Hocko" <mhocko@suse.com>,
"Mike Rapoport" <rppt@kernel.org>,
"Suren Baghdasaryan" <surenb@google.com>,
"Vlastimil Babka" <vbabka@suse.cz>,
linux-mm@kvack.org
Subject: Re: [PATCH v2 2/6] futex: Use RCU-based per-CPU reference counting instead of rcuref_t
Date: Fri, 01 Aug 2025 15:59:06 +0100 [thread overview]
Message-ID: <188efc4a8e37bc5dc64dd18989f9a254ef218449.camel@linaro.org> (raw)
In-Reply-To: <87ldo5ihu0.ffs@tglx>
On Wed, 2025-07-30 at 21:44 +0200, Thomas Gleixner wrote:
> On Wed, Jul 30 2025 at 13:20, André Draszik wrote:
> > kmemleak complains about a new memleak with this commit:
> >
> > [ 680.179004][ T101] kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> >
> > $ cat /sys/kernel/debug/kmemleak
> > unreferenced object (percpu) 0xc22ec0eface8 (size 4):
> > comm "swapper/0", pid 1, jiffies 4294893115
> > hex dump (first 4 bytes on cpu 7):
> > 01 00 00 00 ....
> > backtrace (crc b8bc6765):
> > kmemleak_alloc_percpu+0x48/0xb8
> > pcpu_alloc_noprof+0x6ac/0xb68
> > futex_mm_init+0x60/0xe0
> > mm_init+0x1e8/0x3c0
> > mm_alloc+0x5c/0x78
> > init_args+0x74/0x4b0
> > debug_vm_pgtable+0x60/0x2d8
> >
> > Reverting this commit (and patches 3 and 4 in this series due to context),
> > makes kmemleak happy again.
>
> Unsurprisingly ...
>
> debug_vm_pgtable() allocates it via mm_alloc() -> mm->init() and then
> after the selftest it invokes mmdrop(), which does not free it, as it is
> only freed in __mmput().
>
> The patch below should fix it.
It does. Thanks Thomas!
A.
next prev parent reply other threads:[~2025-08-01 14:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-10 11:00 [PATCH v2 0/6] futex: Use RCU-based per-CPU reference counting Sebastian Andrzej Siewior
2025-07-10 11:00 ` [PATCH v2 1/6] selftests/futex: Adapt the private hash test to RCU related changes Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-10 11:00 ` [PATCH v2 2/6] futex: Use RCU-based per-CPU reference counting instead of rcuref_t Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Peter Zijlstra
2025-08-16 2:38 ` Sean Christopherson
2025-08-26 0:38 ` Sean Christopherson
2025-07-30 12:20 ` [PATCH v2 2/6] " André Draszik
2025-07-30 19:44 ` Thomas Gleixner
2025-08-01 14:59 ` André Draszik [this message]
2025-08-02 13:22 ` [tip: locking/urgent] futex: Move futex cleanup to __mmdrop() tip-bot2 for Thomas Gleixner
2025-08-21 17:39 ` Breno Leitao
2025-07-10 11:00 ` [PATCH v2 3/6] futex: Make futex_private_hash_get() static Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-10 11:00 ` [PATCH v2 4/6] futex: Remove support for IMMUTABLE Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-10 11:00 ` [PATCH v2 5/6] selftests/futex: " Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-10 11:00 ` [PATCH v2 6/6] perf bench futex: " Sebastian Andrzej Siewior
2025-07-11 18:33 ` [tip: locking/futex] " tip-bot2 for Sebastian Andrzej Siewior
2025-07-15 15:59 ` [PATCH v2 0/6] futex: Use RCU-based per-CPU reference counting Shrikanth Hegde
2025-07-15 16:31 ` Sebastian Andrzej Siewior
2025-07-15 17:04 ` Shrikanth Hegde
2025-07-16 14:29 ` Peter Zijlstra
2025-07-16 18:21 ` Shrikanth Hegde
2025-11-06 9:29 ` Peter Zijlstra
2025-11-06 11:09 ` Sebastian Andrzej Siewior
2025-11-06 11:23 ` Peter Zijlstra
2025-11-06 20:17 ` Paul E. McKenney
2025-11-06 11:40 ` [tip: locking/urgent] futex: Optimize per-cpu " tip-bot2 for Peter Zijlstra
2025-11-06 15:26 ` Shrikanth Hegde
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