From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 AB4511A5BB7; Wed, 5 Mar 2025 18:11:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741198288; cv=none; b=SHC8TF3mxEjLhgQnoUIOZVUcQMRHYdKtnertTte6ah3lj6Ansmht1Wx0UFCCzv9fUQ3T8FfjwHsLhkIrNcx82Pb6A+BpRa0iQzmgUvJbf/SoFjmxQJVuyfE47TeLudIRS3fSCvTRK5Y5+bqWX3v+dClIuoZFp6zDjXnVtDQNjUQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741198288; c=relaxed/simple; bh=HWCkRrlYs4P6g7+J9vSTS4WHTW6S3pbbV/TSQNrJieQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=H+hJtRkIRaiDGUT2pzxyAA6U0WvVhXdI1hEq+y+iZvr8CMsg7eoxxhFkVSa7Rgw0ryVPeCUOLLMhq758Sa6zMERSCfLdnKUEop8gtThS2OfUBTI4WiXqDW2xhNz6++F+LVPzGyCn1eTICQDHqJTanIDZZepTc9r9kNKxKBlD6/A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KjF+JEKi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="KjF+JEKi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 338B2C4CED1; Wed, 5 Mar 2025 18:11:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741198288; bh=HWCkRrlYs4P6g7+J9vSTS4WHTW6S3pbbV/TSQNrJieQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KjF+JEKirve+BuCfDQU3RW+PEeMvToxh7o62PvV5oN2+fKix82LjIlKR6slJ7+dVU u2T6PIssBoXekqf2bvcTf6uhRko8K4w22rp5JVlJZ86vVmILrhAEgD1w680suQIDiB SfZ0KWI8To16nsFnKx5VJNO68LgZ0D8V4aQ6Es10= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Woodhouse , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Linus Torvalds Subject: [PATCH 6.12 128/150] sched/core: Prevent rescheduling when interrupts are disabled Date: Wed, 5 Mar 2025 18:49:17 +0100 Message-ID: <20250305174508.956984427@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250305174503.801402104@linuxfoundation.org> References: <20250305174503.801402104@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 82c387ef7568c0d96a918a5a78d9cad6256cfa15 upstream. David reported a warning observed while loop testing kexec jump: Interrupts enabled after irqrouter_resume+0x0/0x50 WARNING: CPU: 0 PID: 560 at drivers/base/syscore.c:103 syscore_resume+0x18a/0x220 kernel_kexec+0xf6/0x180 __do_sys_reboot+0x206/0x250 do_syscall_64+0x95/0x180 The corresponding interrupt flag trace: hardirqs last enabled at (15573): [] __up_console_sem+0x7e/0x90 hardirqs last disabled at (15580): [] __up_console_sem+0x63/0x90 That means __up_console_sem() was invoked with interrupts enabled. Further instrumentation revealed that in the interrupt disabled section of kexec jump one of the syscore_suspend() callbacks woke up a task, which set the NEED_RESCHED flag. A later callback in the resume path invoked cond_resched() which in turn led to the invocation of the scheduler: __cond_resched+0x21/0x60 down_timeout+0x18/0x60 acpi_os_wait_semaphore+0x4c/0x80 acpi_ut_acquire_mutex+0x3d/0x100 acpi_ns_get_node+0x27/0x60 acpi_ns_evaluate+0x1cb/0x2d0 acpi_rs_set_srs_method_data+0x156/0x190 acpi_pci_link_set+0x11c/0x290 irqrouter_resume+0x54/0x60 syscore_resume+0x6a/0x200 kernel_kexec+0x145/0x1c0 __do_sys_reboot+0xeb/0x240 do_syscall_64+0x95/0x180 This is a long standing problem, which probably got more visible with the recent printk changes. Something does a task wakeup and the scheduler sets the NEED_RESCHED flag. cond_resched() sees it set and invokes schedule() from a completely bogus context. The scheduler enables interrupts after context switching, which causes the above warning at the end. Quite some of the code paths in syscore_suspend()/resume() can result in triggering a wakeup with the exactly same consequences. They might not have done so yet, but as they share a lot of code with normal operations it's just a question of time. The problem only affects the PREEMPT_NONE and PREEMPT_VOLUNTARY scheduling models. Full preemption is not affected as cond_resched() is disabled and the preemption check preemptible() takes the interrupt disabled flag into account. Cure the problem by adding a corresponding check into cond_resched(). Reported-by: David Woodhouse Suggested-by: Peter Zijlstra Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Tested-by: David Woodhouse Cc: Linus Torvalds Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/all/7717fe2ac0ce5f0a2c43fdab8b11f4483d54a2a4.camel@infradead.org Signed-off-by: Greg Kroah-Hartman --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7229,7 +7229,7 @@ out_unlock: #if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) int __sched __cond_resched(void) { - if (should_resched(0)) { + if (should_resched(0) && !irqs_disabled()) { preempt_schedule_common(); return 1; }