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From: Christoph Paasch <cpaasch@apple.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, MPTCP Upstream <mptcp@lists.linux.dev>
Subject: kmemleak handling of kfree_rcu
Date: Wed, 30 Aug 2023 09:37:23 -0700	[thread overview]
Message-ID: <F903A825-F05F-4B77-A2B5-7356282FBA2C@apple.com> (raw)

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Hello,

for the MPTCP upstream project, we are running syzkaller [1] continuously to qualify our kernel changes.

We found one issue with kmemleak and its handling of kfree_rcu.


Specifically, it looks like kmemleak falsely reports memory-leaks when the object is being freed by kfree_rcu after a certain grace-period.

For example, https://github.com/multipath-tcp/mptcp_net-next/issues/398#issuecomment-1584819482 shows how the syzkaller program reliably produces a kmemleak report, although the object is not leaked (we confirmed that by simply increasing MSECS_MIN_AGE to something larger than the grace-period).


Is this a known limitation of kmemleak, or is there something else that needs to be done ?



Thanks,
Christoph

[1] https://github.com/google/syzkaller

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             reply	other threads:[~2023-08-30 16:37 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-30 16:37 Christoph Paasch [this message]
2023-09-04 21:22 ` Catalin Marinas
2023-09-05 11:17   ` Joel Fernandes
2023-09-05 14:41     ` Catalin Marinas
2023-09-06 14:35       ` Joel Fernandes
2023-09-06 17:15         ` Catalin Marinas
2023-09-06 19:11           ` Paul E. McKenney
2023-09-06 21:37             ` Catalin Marinas
2023-09-06 22:02               ` Paul E. McKenney
2023-09-06 23:10                 ` Joel Fernandes
2023-09-12 13:15           ` Matthieu Baerts
2023-09-12 13:32             ` Joel Fernandes
2023-09-05 21:22   ` Christoph Paasch
2023-09-06 17:21     ` Catalin Marinas
2023-09-10 23:10       ` Joel Fernandes
2023-09-11 17:41         ` Christoph Paasch
2023-09-12  9:52           ` Catalin Marinas

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