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 F28233F23C5; Wed, 20 May 2026 18:06:43 +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=1779300405; cv=none; b=uRhotveyHOPib99/28CD/UVwZfuO8mEmqYKt7g+laqXhyEhlGmftXtTAY/P62KmfjXeYbM9Z1TL1EAXDzRujNGCoiY7rb1jy2qFZDVGi/cDefci2m0vVSHMzijNczQTYEFMWURQbG8BxqdFGtH6DmAZjQOseZU+1nLwOfAfnV6U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779300405; c=relaxed/simple; bh=OYm3otGO+HR8MWllN/+iQBsj03iBwp6aG8hhjseMFkQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SqEaN+NUt7m4qbi4KGCRHJGe7Xm73Qe1RMw0XsIEeTS2NkdJU/qsFBxE2Z2wQEsjRL20y46iNANGk+I7iVFaa8OfNmDsNRWi6/dTPAtMuNy3EcaxzLSZpvOUgnh3XwsdcY6e29vZ/ErLrB1Sz2vA47LmbIWBRZR7KKdwZD8ilqM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QoVPBfi1; 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="QoVPBfi1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 645861F000E9; Wed, 20 May 2026 18:06:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779300403; bh=c4Kg+NFuKxvQ/MLAVKXe3nynv9VcFYG9FKtxeaszgwo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=QoVPBfi1guNCZm6oyzcdTCCeNVcpDAaGdC20gqU/0Fdrs3MrPhql6uWLkT1GnPOEG Z8pBmYfBfWoVVIy1buqIKe/7BKGiadFjO+LxjOvYAwQI9eonj+AZe7mkRe9QWX4W+x h3TaG+jjH/ab+nQOMBbd6lfNN/6JtLmzeqwFeG4A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+123e1b70473ce213f3af@syzkaller.appspotmail.com, Daniel Jordan , Herbert Xu , Sasha Levin , Thomas Gleixner Subject: [PATCH 6.12 160/666] padata: Put CPU offline callback in ONLINE section to allow failure Date: Wed, 20 May 2026 18:16:11 +0200 Message-ID: <20260520162114.675587392@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162111.222830634@linuxfoundation.org> References: <20260520162111.222830634@linuxfoundation.org> User-Agent: quilt/0.69 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: Daniel Jordan [ Upstream commit c8c4a2972f83c8b68ff03b43cecdb898939ff851 ] syzbot reported the following warning: DEAD callback error for CPU1 WARNING: kernel/cpu.c:1463 at _cpu_down+0x759/0x1020 kernel/cpu.c:1463, CPU#0: syz.0.1960/14614 at commit 4ae12d8bd9a8 ("Merge tag 'kbuild-fixes-7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux") which tglx traced to padata_cpu_dead() given it's the only sub-CPUHP_TEARDOWN_CPU callback that returns an error. Failure isn't allowed in hotplug states before CPUHP_TEARDOWN_CPU so move the CPU offline callback to the ONLINE section where failure is possible. Fixes: 894c9ef9780c ("padata: validate cpumask without removed CPU during offline") Reported-by: syzbot+123e1b70473ce213f3af@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/69af0a05.050a0220.310d8.002f.GAE@google.com/ Debugged-by: Thomas Gleixner Signed-off-by: Daniel Jordan Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin --- include/linux/cpuhotplug.h | 1 - include/linux/padata.h | 8 +-- kernel/padata.c | 120 +++++++++++++++++++------------------ 3 files changed, 65 insertions(+), 64 deletions(-) diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 2361ed4d2b152..6645faf1cc1d5 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -94,7 +94,6 @@ enum cpuhp_state { CPUHP_PCI_XGENE_DEAD, CPUHP_IOMMU_IOVA_DEAD, CPUHP_AP_ARM_CACHE_B15_RAC_DEAD, - CPUHP_PADATA_DEAD, CPUHP_AP_DTPM_CPU_DEAD, CPUHP_RANDOM_PREPARE, CPUHP_WORKQUEUE_PREP, diff --git a/include/linux/padata.h b/include/linux/padata.h index 765f2778e264a..b6232bea6edf5 100644 --- a/include/linux/padata.h +++ b/include/linux/padata.h @@ -149,23 +149,23 @@ struct padata_mt_job { /** * struct padata_instance - The overall control structure. * - * @cpu_online_node: Linkage for CPU online callback. - * @cpu_dead_node: Linkage for CPU offline callback. + * @cpuhp_node: Linkage for CPU hotplug callbacks. * @parallel_wq: The workqueue used for parallel work. * @serial_wq: The workqueue used for serial work. * @pslist: List of padata_shell objects attached to this instance. * @cpumask: User supplied cpumasks for parallel and serial works. + * @validate_cpumask: Internal cpumask used to validate @cpumask during hotplug. * @kobj: padata instance kernel object. * @lock: padata instance lock. * @flags: padata flags. */ struct padata_instance { - struct hlist_node cpu_online_node; - struct hlist_node cpu_dead_node; + struct hlist_node cpuhp_node; struct workqueue_struct *parallel_wq; struct workqueue_struct *serial_wq; struct list_head pslist; struct padata_cpumask cpumask; + cpumask_var_t validate_cpumask; struct kobject kobj; struct mutex lock; u8 flags; diff --git a/kernel/padata.c b/kernel/padata.c index af10aff28ff68..483239c7fe826 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -558,7 +558,8 @@ static void padata_init_reorder_list(struct parallel_data *pd) } /* Allocate and initialize the internal cpumask dependend resources. */ -static struct parallel_data *padata_alloc_pd(struct padata_shell *ps) +static struct parallel_data *padata_alloc_pd(struct padata_shell *ps, + int offlining_cpu) { struct padata_instance *pinst = ps->pinst; struct parallel_data *pd; @@ -584,6 +585,10 @@ static struct parallel_data *padata_alloc_pd(struct padata_shell *ps) cpumask_and(pd->cpumask.pcpu, pinst->cpumask.pcpu, cpu_online_mask); cpumask_and(pd->cpumask.cbcpu, pinst->cpumask.cbcpu, cpu_online_mask); + if (offlining_cpu >= 0) { + __cpumask_clear_cpu(offlining_cpu, pd->cpumask.pcpu); + __cpumask_clear_cpu(offlining_cpu, pd->cpumask.cbcpu); + } padata_init_reorder_list(pd); padata_init_squeues(pd); @@ -630,11 +635,11 @@ static void __padata_stop(struct padata_instance *pinst) } /* Replace the internal control structure with a new one. */ -static int padata_replace_one(struct padata_shell *ps) +static int padata_replace_one(struct padata_shell *ps, int offlining_cpu) { struct parallel_data *pd_new; - pd_new = padata_alloc_pd(ps); + pd_new = padata_alloc_pd(ps, offlining_cpu); if (!pd_new) return -ENOMEM; @@ -644,7 +649,7 @@ static int padata_replace_one(struct padata_shell *ps) return 0; } -static int padata_replace(struct padata_instance *pinst) +static int padata_replace(struct padata_instance *pinst, int offlining_cpu) { struct padata_shell *ps; int err = 0; @@ -652,7 +657,7 @@ static int padata_replace(struct padata_instance *pinst) pinst->flags |= PADATA_RESET; list_for_each_entry(ps, &pinst->pslist, list) { - err = padata_replace_one(ps); + err = padata_replace_one(ps, offlining_cpu); if (err) break; } @@ -669,9 +674,21 @@ static int padata_replace(struct padata_instance *pinst) /* If cpumask contains no active cpu, we mark the instance as invalid. */ static bool padata_validate_cpumask(struct padata_instance *pinst, - const struct cpumask *cpumask) + const struct cpumask *cpumask, + int offlining_cpu) { - if (!cpumask_intersects(cpumask, cpu_online_mask)) { + cpumask_copy(pinst->validate_cpumask, cpu_online_mask); + + /* + * @offlining_cpu is still in cpu_online_mask, so remove it here for + * validation. Using a sub-CPUHP_TEARDOWN_CPU hotplug state where + * @offlining_cpu wouldn't be in the online mask doesn't work because + * padata_cpu_offline() can fail but such a state doesn't allow failure. + */ + if (offlining_cpu >= 0) + __cpumask_clear_cpu(offlining_cpu, pinst->validate_cpumask); + + if (!cpumask_intersects(cpumask, pinst->validate_cpumask)) { pinst->flags |= PADATA_INVALID; return false; } @@ -687,13 +704,13 @@ static int __padata_set_cpumasks(struct padata_instance *pinst, int valid; int err; - valid = padata_validate_cpumask(pinst, pcpumask); + valid = padata_validate_cpumask(pinst, pcpumask, -1); if (!valid) { __padata_stop(pinst); goto out_replace; } - valid = padata_validate_cpumask(pinst, cbcpumask); + valid = padata_validate_cpumask(pinst, cbcpumask, -1); if (!valid) __padata_stop(pinst); @@ -701,7 +718,7 @@ static int __padata_set_cpumasks(struct padata_instance *pinst, cpumask_copy(pinst->cpumask.pcpu, pcpumask); cpumask_copy(pinst->cpumask.cbcpu, cbcpumask); - err = padata_setup_cpumasks(pinst) ?: padata_replace(pinst); + err = padata_setup_cpumasks(pinst) ?: padata_replace(pinst, -1); if (valid) __padata_start(pinst); @@ -753,26 +770,6 @@ EXPORT_SYMBOL(padata_set_cpumask); #ifdef CONFIG_HOTPLUG_CPU -static int __padata_add_cpu(struct padata_instance *pinst, int cpu) -{ - int err = padata_replace(pinst); - - if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) && - padata_validate_cpumask(pinst, pinst->cpumask.cbcpu)) - __padata_start(pinst); - - return err; -} - -static int __padata_remove_cpu(struct padata_instance *pinst, int cpu) -{ - if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) || - !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu)) - __padata_stop(pinst); - - return padata_replace(pinst); -} - static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu) { return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) || @@ -784,27 +781,39 @@ static int padata_cpu_online(unsigned int cpu, struct hlist_node *node) struct padata_instance *pinst; int ret; - pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node); + pinst = hlist_entry_safe(node, struct padata_instance, cpuhp_node); if (!pinst_has_cpu(pinst, cpu)) return 0; mutex_lock(&pinst->lock); - ret = __padata_add_cpu(pinst, cpu); + + ret = padata_replace(pinst, -1); + + if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu, -1) && + padata_validate_cpumask(pinst, pinst->cpumask.cbcpu, -1)) + __padata_start(pinst); + mutex_unlock(&pinst->lock); return ret; } -static int padata_cpu_dead(unsigned int cpu, struct hlist_node *node) +static int padata_cpu_offline(unsigned int cpu, struct hlist_node *node) { struct padata_instance *pinst; int ret; - pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node); + pinst = hlist_entry_safe(node, struct padata_instance, cpuhp_node); if (!pinst_has_cpu(pinst, cpu)) return 0; mutex_lock(&pinst->lock); - ret = __padata_remove_cpu(pinst, cpu); + + if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu, cpu) || + !padata_validate_cpumask(pinst, pinst->cpumask.cbcpu, cpu)) + __padata_stop(pinst); + + ret = padata_replace(pinst, cpu); + mutex_unlock(&pinst->lock); return ret; } @@ -815,15 +824,14 @@ static enum cpuhp_state hp_online; static void __padata_free(struct padata_instance *pinst) { #ifdef CONFIG_HOTPLUG_CPU - cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD, - &pinst->cpu_dead_node); - cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpu_online_node); + cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpuhp_node); #endif WARN_ON(!list_empty(&pinst->pslist)); free_cpumask_var(pinst->cpumask.pcpu); free_cpumask_var(pinst->cpumask.cbcpu); + free_cpumask_var(pinst->validate_cpumask); destroy_workqueue(pinst->serial_wq); destroy_workqueue(pinst->parallel_wq); kfree(pinst); @@ -983,10 +991,10 @@ struct padata_instance *padata_alloc(const char *name) if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL)) goto err_free_serial_wq; - if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) { - free_cpumask_var(pinst->cpumask.pcpu); - goto err_free_serial_wq; - } + if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) + goto err_free_p_mask; + if (!alloc_cpumask_var(&pinst->validate_cpumask, GFP_KERNEL)) + goto err_free_cb_mask; INIT_LIST_HEAD(&pinst->pslist); @@ -994,7 +1002,7 @@ struct padata_instance *padata_alloc(const char *name) cpumask_copy(pinst->cpumask.cbcpu, cpu_possible_mask); if (padata_setup_cpumasks(pinst)) - goto err_free_masks; + goto err_free_v_mask; __padata_start(pinst); @@ -1003,18 +1011,19 @@ struct padata_instance *padata_alloc(const char *name) #ifdef CONFIG_HOTPLUG_CPU cpuhp_state_add_instance_nocalls_cpuslocked(hp_online, - &pinst->cpu_online_node); - cpuhp_state_add_instance_nocalls_cpuslocked(CPUHP_PADATA_DEAD, - &pinst->cpu_dead_node); + &pinst->cpuhp_node); #endif cpus_read_unlock(); return pinst; -err_free_masks: - free_cpumask_var(pinst->cpumask.pcpu); +err_free_v_mask: + free_cpumask_var(pinst->validate_cpumask); +err_free_cb_mask: free_cpumask_var(pinst->cpumask.cbcpu); +err_free_p_mask: + free_cpumask_var(pinst->cpumask.pcpu); err_free_serial_wq: destroy_workqueue(pinst->serial_wq); err_put_cpus: @@ -1057,7 +1066,7 @@ struct padata_shell *padata_alloc_shell(struct padata_instance *pinst) ps->pinst = pinst; cpus_read_lock(); - pd = padata_alloc_pd(ps); + pd = padata_alloc_pd(ps, -1); cpus_read_unlock(); if (!pd) @@ -1106,32 +1115,25 @@ void __init padata_init(void) int ret; ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "padata:online", - padata_cpu_online, NULL); + padata_cpu_online, padata_cpu_offline); if (ret < 0) goto err; hp_online = ret; - - ret = cpuhp_setup_state_multi(CPUHP_PADATA_DEAD, "padata:dead", - NULL, padata_cpu_dead); - if (ret < 0) - goto remove_online_state; #endif possible_cpus = num_possible_cpus(); padata_works = kmalloc_array(possible_cpus, sizeof(struct padata_work), GFP_KERNEL); if (!padata_works) - goto remove_dead_state; + goto remove_online_state; for (i = 0; i < possible_cpus; ++i) list_add(&padata_works[i].pw_list, &padata_free_works); return; -remove_dead_state: -#ifdef CONFIG_HOTPLUG_CPU - cpuhp_remove_multi_state(CPUHP_PADATA_DEAD); remove_online_state: +#ifdef CONFIG_HOTPLUG_CPU cpuhp_remove_multi_state(hp_online); err: #endif -- 2.53.0