From: Joel Fernandes <joelagnelf@nvidia.com>
To: Kunwu Chan <kunwu.chan@gmail.com>
Cc: jiangshanlai@gmail.com, paulmck@kernel.org,
josh@joshtriplett.org, work@onurozkan.dev, frederic@kernel.org,
neeraj.upadhyay@kernel.org, boqun@kernel.org, urezki@gmail.com,
rostedt@goodmis.org, mathieu.desnoyers@efficios.com,
qiang.zhang@linux.dev, rcu@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 00/10] rcu: Improve callback diagnostics and validation
Date: Tue, 27 Oct 2026 19:13:15 -0400 [thread overview]
Message-ID: <20261027231315.GA3580680@joelbox> (raw)
In-Reply-To: <20261027070923.3054462-1-kunwu.chan@gmail.com>
On Tue, Oct 27, 2026 at 03:09:13PM +0800, Kunwu Chan wrote:
> Hi,
>
> This series improves callback diagnostics and validation across RCU,
> SRCU, and RCU Tasks.
>
> Patches 1-3 record callback registration stacks for KASAN in Tree
> SRCU, Tiny SRCU, and Tiny RCU. KASAN prints the recorded auxiliary
> stack when reporting a use-after-free.
>
> Patches 4-6 add rcu_head alignment and NULL callback-function checks.
>
> Patches 7-10 detect duplicate callback enqueue attempts before
> queueing, using the RCU head debug-object mechanism. A duplicate
> registration is rejected at entry and __ratelimit() controls the
> diagnostic output group (pr_err, mem_dump_obj, dump_stack).
> Detection requires CONFIG_DEBUG_OBJECTS_RCU_HEAD.
>
> Changes since v1:
> - Patches 7-9: __ratelimit() + dump_stack() instead of hard-coded limit
> - Patch 10 (new): same change for Tree RCU's rcu_do_enqueue()
> - Patch 9: fixed log format to avoid pseudo-function names
> - Tags: Reviewed-by (4-6), Suggested-by (7-10)
> - v1: https://lore.kernel.org/all/20261023101841.2910719-1-kunwu.chan@gmail.com/
>
>
> Testing:
> rcutorture with KASAN (SRCU-N, SRCU-P, SRCU-T, SRCU-U, TINY01,
> TINY02, TREE03, 3min each): all exitcode 0.
>
> KASAN aux stack (QEMU, CONFIG_KASAN_GENERIC=y):
> Last potentially related work creation:
> kasan_save_stack+0x33/0x60
> kasan_record_aux_stack+0x8c/0xa0
> call_srcu+0xb2/0x390
>
> Duplicate enqueue (QEMU, CONFIG_DEBUG_OBJECTS_RCU_HEAD=y):
> call_srcu(): Duplicate call_srcu() CB ... ->cb
> dump_stack_lvl+0x47/0x60
> call_rcu_tasks_generic(): Duplicate CB for RCU Tasks, ... ->cb
> dump_stack_lvl+0x47/0x60
> rcu_do_enqueue(): Double-freed CB ... ->cb slab kmalloc-16 ...
>
>
> Kunwu Chan (10):
> srcu: Record callback registration stack for KASAN
> srcutiny: Record callback registration stack for KASAN
> rcu: Record callback registration stack for Tiny RCU
> srcu: Validate callback arguments
> rcu: Validate callback arguments in Tiny RCU
> rcu-tasks: Validate callback arguments
> srcu: Detect duplicate callback enqueue at registration
> srcutiny: Detect duplicate callback enqueue
> rcu-tasks: Detect duplicate callback enqueue
> rcu: Improve duplicate callback diagnostics
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
All look good to me, applying for further testing and review for 7.5. Did you
also test double-call-srcu and confirm intended behavior? Thanks!
thanks,
Joel Fernandes
>
> kernel/rcu/srcutiny.c | 34 ++++++++++++++++++++++++++++++++++
> kernel/rcu/srcutree.c | 36 ++++++++++++++++++++++++++++++------
> kernel/rcu/tasks.h | 27 +++++++++++++++++++++++++++
> kernel/rcu/tiny.c | 11 +++++++++++
> kernel/rcu/tree.c | 9 +++++++--
> 5 files changed, 109 insertions(+), 8 deletions(-)
>
>
> base-commit: 940793b926aa94bf65ec404043050888e3053188
> --
> 2.43.0
>
next prev parent reply other threads:[~2026-10-27 23:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-27 7:09 [PATCH v2 00/10] rcu: Improve callback diagnostics and validation Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 01/10] srcu: Record callback registration stack for KASAN Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 02/10] srcutiny: " Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 03/10] rcu: Record callback registration stack for Tiny RCU Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 04/10] srcu: Validate callback arguments Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 05/10] rcu: Validate callback arguments in Tiny RCU Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 06/10] rcu-tasks: Validate callback arguments Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 07/10] srcu: Detect duplicate callback enqueue at registration Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 08/10] srcutiny: Detect duplicate callback enqueue Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 09/10] rcu-tasks: " Kunwu Chan
2026-10-27 7:09 ` [PATCH v2 10/10] rcu: Improve duplicate callback diagnostics Kunwu Chan
2026-10-27 23:13 ` Joel Fernandes [this message]
2026-10-28 2:17 ` [PATCH v2 00/10] rcu: Improve callback diagnostics and validation KunWu Chan
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