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 22B84249F9; Tue, 11 Mar 2025 15:16:16 +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=1741706176; cv=none; b=gIf0Gjqa6hfz4Qne122+/bryCBeCBtgq3289OzXFWXnqqJKeRrycZ4VtFNprRGOQkJ3yvnLc00Ftmc0zKQA/GAWy8MGhrRta9+Gq1bl04GX1Y5yZKisOCR+jUEsxDIKHkj0nLSbHDn3kI1w6xdGA5GcKA0sMdgkhnxF4VYA4E5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741706176; c=relaxed/simple; bh=Gq4wNAv3unGBiXYv5qdNjyXq+iA1a10nTfXGnmcmf2M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sLmPv8kx8JyOFKaGjb39LwVtMcc8gADMfAbD6mm3F0KUR4fdz2N5FDbNgYtR7mw9jJfvQtAwvOMa1CpI3nrD2oEn6/1JiSlwJo+So9mdBjcq5pyVuwCpvB7LenucR098oCa+nR1yWOuBUFN757bom54ErVUUBarrgHTGG89RkvA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tLtm04pm; 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="tLtm04pm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D120C4CEE9; Tue, 11 Mar 2025 15:16:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741706176; bh=Gq4wNAv3unGBiXYv5qdNjyXq+iA1a10nTfXGnmcmf2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tLtm04pmd/zKooPw8okYO74qTfvNDsOo3DFZ2dC30YMW1w4GcbV/A76Oht/1mj/zB UG3JyI8KDNDCa3DNeIZHf36/Y7BVAl5bsh/83UtuT6I8WPxzndCN37UMQG2z4zdqwh HUZC3erAEx85tf8GNapirFz4puS19XbZknqyhCXU= 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 5.4 270/328] sched/core: Prevent rescheduling when interrupts are disabled Date: Tue, 11 Mar 2025 16:00:40 +0100 Message-ID: <20250311145725.641131217@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250311145714.865727435@linuxfoundation.org> References: <20250311145714.865727435@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 5.4-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 @@ -5714,7 +5714,7 @@ SYSCALL_DEFINE0(sched_yield) #ifndef CONFIG_PREEMPTION int __sched _cond_resched(void) { - if (should_resched(0)) { + if (should_resched(0) && !irqs_disabled()) { preempt_schedule_common(); return 1; }