From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC1933C9EEE; Thu, 2 Jul 2026 16:45:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010717; cv=none; b=J9oYsO077H8dD6kG+ARaz6DIzCyP4N6bdCUP9KvSc2cvPGrz0xHNVUb79FuW0x3wCCQVQC0oj+h7eDd9GhSFvXL7ObPzL8RLmlrywoyiuiW6exrWRZ2qt68QtrST0l2fAKCL5li4tXtNsSR1Y7fUtEXluTaUivDiFF+KU7kLLR4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783010717; c=relaxed/simple; bh=wR9S9x3CVLPr4/NdYpHg9Sn/jEWxDJ9J9M/1EhCawE0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=juQonwa/jeh7j6A7l9ojgSz3PSJwPMh6x+TSEKvF3VwsKZbw/w8tfqAjuNSaeNLH5Ab7d1SHcbcxucVt9pxGVbneeEGhCqf3sJRiyRy0Jzd+Scw4+l+8DIzGg2eUWwoBGoku/tlXfDjRcuRh8v4KcqLQaXTKL4JXPBgiPpmgCeI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hOFWFzC/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hOFWFzC/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DDBB1F000E9; Thu, 2 Jul 2026 16:45:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783010716; bh=WO++asFjHivOlvNF0CT3+k6GJppv/UwJR+cwGOZwj9M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hOFWFzC/Ej8MoqWS0AV9l3s3cJYc+0UfcyUkoPXr0seTeTcDBbpSQDpghRI9OpaSl 12uuWWyOzB3ttWhW8Dl/YAN/BuccT+ayxoMx9w1WwszgbxZbDzOVa+IBV+mrZhHgyw UKq0cZGXtzz4Z0kI0UnHw4TJ9zZhNrnNZzf8icwc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sebastian Andrzej Siewior , Thomas Gleixner , Waiman Long , Thomas Gleixner , Sasha Levin Subject: [PATCH 6.6 011/175] debugobjects: Dont call fill_pool() in early boot hardirq context Date: Thu, 2 Jul 2026 18:18:32 +0200 Message-ID: <20260702155116.007693929@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155115.766838875@linuxfoundation.org> References: <20260702155115.766838875@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Waiman Long commit 0d046ae106255cba5eb83b23f78ee93f3620247d upstream. When booting a debug PREEMPT_RT kernel on an ARM64 system, a "inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage" lockdep warning message was reported to the console. During early boot, interrupts are enabled before the scheduler is enabled. In this window (before SYSTEM_SCHEDULING is set) interrupts can fire and in the hard interrupt context handler attempt to fill the pool This can lead to a deadlock when the interrupt occurred when the interrupt hits a region which holds a lock that is required to be taken in the allocation path. Add a new can_fill_pool() helper and reorder the exception rule and forbid this scenario by excluding allocations from hard interrupt context. Fixes: 06e0ae988f6e ("debugobjects: Allow to refill the pool before SYSTEM_SCHEDULING") Suggested-by: Sebastian Andrzej Siewior Suggested-by: Thomas Gleixner Signed-off-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Sebastian Andrzej Siewior Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260605173038.495075-1-longman@redhat.com Signed-off-by: Sasha Levin --- lib/debugobjects.c | 44 ++++++++++++++++++++++++++++++++++++-------- 1 file changed, 36 insertions(+), 8 deletions(-) diff --git a/lib/debugobjects.c b/lib/debugobjects.c index b1c3e873a71d40..e4ef9d032d1749 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -606,20 +606,48 @@ static inline bool debug_objects_is_pi_blocked_on(void) #endif } -static void debug_objects_fill_pool(void) +static inline bool can_fill_pool(void) { /* - * On RT enabled kernels the pool refill must happen in preemptible - * context and not enqueued on an rt_mutex -- for !RT kernels we rely - * on the fact that spinlock_t and raw_spinlock_t are basically the - * same type and this lock-type inversion works just fine. + * On !RT enabled kernels there are no restrictions and spinlock_t and + * raw_spinlock_t are the same types. + */ + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + return true; + + /* + * On RT enabled kernels, the task must not be blocked on a lock as + * that could corrupt the PI state when blocking on a lock in the + * allocation path. + */ + if (debug_objects_is_pi_blocked_on()) + return false; + + /* + * On RT enabled kernels the pool refill should happen in preemptible + * context. */ - if (!IS_ENABLED(CONFIG_PREEMPT_RT) || system_state < SYSTEM_SCHEDULING || - (preemptible() && !debug_objects_is_pi_blocked_on())) { + if (preemptible()) + return true; + + /* + * Though during system boot before scheduling is set up, preemption is + * disabled and the pool can get exhausted. Before scheduling is active + * a task cannot be blocked on a sleeping lock, but it might hold a lock + * and if interrupted then hard interrupt context might run into a lock + * inversion. So exclude hard interrupt context from allocations before + * scheduling is active. + */ + return system_state < SYSTEM_SCHEDULING && !in_hardirq(); +} + +static void debug_objects_fill_pool(void) +{ + if (can_fill_pool()) { /* * Annotate away the spinlock_t inside raw_spinlock_t warning * by temporarily raising the wait-type to LD_WAIT_CONFIG, matching - * the preemptible() condition above. + * the preemptible() condition in can_fill_pool(). */ static DEFINE_WAIT_OVERRIDE_MAP(fill_pool_map, LD_WAIT_CONFIG); lock_map_acquire_try(&fill_pool_map); -- 2.53.0