From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 408C5C47096 for ; Thu, 3 Jun 2021 07:57:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F6CB613E3 for ; Thu, 3 Jun 2021 07:57:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229864AbhFCH6o (ORCPT ); Thu, 3 Jun 2021 03:58:44 -0400 Received: from m43-7.mailgun.net ([69.72.43.7]:10556 "EHLO m43-7.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229576AbhFCH6n (ORCPT ); Thu, 3 Jun 2021 03:58:43 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1622707019; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=6WRgPAl+BB4MAUcBvy9HDIQZdPB119OrpSi4TO9lRUQ=; b=h3EeflOdg5m7Del6Pcx//GiSdkQH0B7sfcxB77y1cJpPfR7c9HIFF8yHHPXEzuLy7LHHp6CG zbWTQUsArUUAIAOAkVGYqyQC0RVjjagk2y1JOut374qwLiQm+E3EVt2NGtuKfM9z8j5Nd03b QHxpk07Nr52f79Mfy305TkYiXKs= X-Mailgun-Sending-Ip: 69.72.43.7 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-east-1.postgun.com with SMTP id 60b88b38f726fa4188568229 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 03 Jun 2021 07:56:40 GMT Sender: faiyazm=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id C4A67C433D3; Thu, 3 Jun 2021 07:56:39 +0000 (UTC) Received: from [192.168.0.105] (unknown [49.204.181.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: faiyazm) by smtp.codeaurora.org (Postfix) with ESMTPSA id 7BF52C4338A; Thu, 3 Jun 2021 07:56:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 7BF52C4338A Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=faiyazm@codeaurora.org Subject: Re: [PATCH v8] mm: slub: move sysfs slab alloc/free interfaces to debugfs To: Vlastimil Babka , cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, greg@kroah.com, glittao@gmail.com Cc: vinmenon@codeaurora.org References: <1622542057-14632-1-git-send-email-faiyazm@codeaurora.org> <8c6db046-9f12-e670-8fe0-6d34f9328a52@suse.cz> From: Faiyaz Mohammed Message-ID: <3cd98e90-8373-dc4d-cc25-99fa18c2d73c@codeaurora.org> Date: Thu, 3 Jun 2021 13:26:30 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <8c6db046-9f12-e670-8fe0-6d34f9328a52@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/1/2021 7:01 PM, Vlastimil Babka wrote: > On 6/1/21 12:07 PM, Faiyaz Mohammed wrote: >> alloc_calls and free_calls implementation in sysfs have two issues, >> one is PAGE_SIZE limitiation of sysfs and other is it does not adhere >> to "one value per file" rule. >> >> To overcome this issues, move the alloc_calls and free_calls implemeation >> to debugfs. >> >> Debugfs cache will be created if SLAB_STORE_USER flag is set. >> >> Rename the alloc_calls/free_calls to alloc_traces/free_traces, >> to be inline with what it does. >> >> Signed-off-by: Faiyaz Mohammed > > When reading the files I'm getting dmesg errors like this: > > [ 37.998152] seq_file: buggy .next function slab_debugfs_next did not update > position index > > Don't recall this from previous versions? > slab_debugfs_next() is not updating the pos after last read, so it's retuning null. In fs/seq_file.c if pos is not updated in ->next() fn, it's printing the above info but I will address this in next patch version. >> diff --git a/mm/slab_common.c b/mm/slab_common.c >> index a4a5714..ca39e84 100644 >> --- a/mm/slab_common.c >> +++ b/mm/slab_common.c >> @@ -449,6 +449,7 @@ static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) >> rcu_barrier(); >> >> list_for_each_entry_safe(s, s2, &to_destroy, list) { >> + debugfs_slab_release(s); > > You should remove this one, you already do the release when queueing the work > below. This is not like sysfs where we distinguish _unlink() when queueing and > _release when processing the work. > oh, yes, I will update in next patch version. >> +static struct dentry *slab_debugfs_root; >> +struct loc_track t = { 0, 0, NULL }; > > Ooops, this can't be a global variable, especially when shared without any lock > protection - but even with a protection it would be very suboptimal. You'll need > to make it a seq_file private, see e.g. here for an example: > https://lore.kernel.org/linux-mm/20210521121127.24653-3-glittao@gmail.com/ > I will address this in next patch version. >> static void free_loc_track(struct loc_track *t) >> { >> if (t->max) >> @@ -4825,82 +4840,7 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s, >> add_location(t, s, get_track(s, p, alloc)); >> put_map(map); >> } >> - >> -static int list_locations(struct kmem_cache *s, char *buf, >> - enum track_item alloc) >> -{ >> - int len = 0; >> - unsigned long i; >> - struct loc_track t = { 0, 0, NULL }; >> - int node; >> - struct kmem_cache_node *n; >> - >> - if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location), >> - GFP_KERNEL)) { >> - return sysfs_emit(buf, "Out of memory\n"); >> - } >> - /* Push back cpu slabs */ >> - flush_all(s); >> - >> - for_each_kmem_cache_node(s, node, n) { >> - unsigned long flags; >> - struct page *page; >> - >> - if (!atomic_long_read(&n->nr_slabs)) >> - continue; >> - >> - spin_lock_irqsave(&n->list_lock, flags); >> - list_for_each_entry(page, &n->partial, slab_list) >> - process_slab(&t, s, page, alloc); >> - list_for_each_entry(page, &n->full, slab_list) >> - process_slab(&t, s, page, alloc); >> - spin_unlock_irqrestore(&n->list_lock, flags); >> - } >> - >> - for (i = 0; i < t.count; i++) { >> - struct location *l = &t.loc[i]; >> - >> - len += sysfs_emit_at(buf, len, "%7ld ", l->count); >> - >> - if (l->addr) >> - len += sysfs_emit_at(buf, len, "%pS", (void *)l->addr); >> - else >> - len += sysfs_emit_at(buf, len, ""); >> - >> - if (l->sum_time != l->min_time) >> - len += sysfs_emit_at(buf, len, " age=%ld/%ld/%ld", >> - l->min_time, >> - (long)div_u64(l->sum_time, >> - l->count), >> - l->max_time); >> - else >> - len += sysfs_emit_at(buf, len, " age=%ld", l->min_time); >> - >> - if (l->min_pid != l->max_pid) >> - len += sysfs_emit_at(buf, len, " pid=%ld-%ld", >> - l->min_pid, l->max_pid); >> - else >> - len += sysfs_emit_at(buf, len, " pid=%ld", >> - l->min_pid); >> - >> - if (num_online_cpus() > 1 && >> - !cpumask_empty(to_cpumask(l->cpus))) >> - len += sysfs_emit_at(buf, len, " cpus=%*pbl", >> - cpumask_pr_args(to_cpumask(l->cpus))); >> - >> - if (nr_online_nodes > 1 && !nodes_empty(l->nodes)) >> - len += sysfs_emit_at(buf, len, " nodes=%*pbl", >> - nodemask_pr_args(&l->nodes)); >> - >> - len += sysfs_emit_at(buf, len, "\n"); >> - } >> - >> - free_loc_track(&t); >> - if (!t.count) >> - len += sysfs_emit_at(buf, len, "No data\n"); >> - >> - return len; >> -} >> +#endif /* CONFIG_DEBUG_FS */ >> #endif /* CONFIG_SLUB_DEBUG */ >> >> #ifdef SLUB_RESILIENCY_TEST >> @@ -5350,21 +5290,6 @@ static ssize_t validate_store(struct kmem_cache *s, >> } >> SLAB_ATTR(validate); >> >> -static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf) >> -{ >> - if (!(s->flags & SLAB_STORE_USER)) >> - return -ENOSYS; >> - return list_locations(s, buf, TRACK_ALLOC); >> -} >> -SLAB_ATTR_RO(alloc_calls); >> - >> -static ssize_t free_calls_show(struct kmem_cache *s, char *buf) >> -{ >> - if (!(s->flags & SLAB_STORE_USER)) >> - return -ENOSYS; >> - return list_locations(s, buf, TRACK_FREE); >> -} >> -SLAB_ATTR_RO(free_calls); >> #endif /* CONFIG_SLUB_DEBUG */ >> >> #ifdef CONFIG_FAILSLAB >> @@ -5528,8 +5453,6 @@ static struct attribute *slab_attrs[] = { >> &poison_attr.attr, >> &store_user_attr.attr, >> &validate_attr.attr, >> - &alloc_calls_attr.attr, >> - &free_calls_attr.attr, >> #endif >> #ifdef CONFIG_ZONE_DMA >> &cache_dma_attr.attr, >> @@ -5818,6 +5741,203 @@ static int __init slab_sysfs_init(void) >> __initcall(slab_sysfs_init); >> #endif /* CONFIG_SYSFS */ >> >> +#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS) >> +static int slab_debugfs_show(struct seq_file *seq, void *v) >> +{ >> + >> + struct location *l; >> + unsigned int idx = *(unsigned int *)v; >> + >> + if (idx < t.count) { >> + l = &t.loc[idx]; >> + >> + seq_printf(seq, "%7ld ", l->count); >> + >> + if (l->addr) >> + seq_printf(seq, "%pS", (void *)l->addr); >> + else >> + seq_puts(seq, ""); >> + >> + if (l->sum_time != l->min_time) { >> + seq_printf(seq, " age=%ld/%ld/%ld", >> + l->min_time, >> + (long)div_u64(l->sum_time, l->count), >> + l->max_time); >> + } else >> + seq_printf(seq, " age=%ld", >> + l->min_time); >> + >> + if (l->min_pid != l->max_pid) >> + seq_printf(seq, " pid=%ld-%ld", >> + l->min_pid, l->max_pid); >> + else >> + seq_printf(seq, " pid=%ld", >> + l->min_pid); >> + >> + if (num_online_cpus() > 1 && >> + !cpumask_empty(to_cpumask(l->cpus))) >> + seq_printf(seq, " cpus=%*pbl", >> + cpumask_pr_args(to_cpumask(l->cpus))); >> + >> + if (nr_online_nodes > 1 && !nodes_empty(l->nodes)) >> + seq_printf(seq, " nodes=%*pbl", >> + nodemask_pr_args(&l->nodes)); >> + >> + seq_puts(seq, "\n"); >> + } >> + >> + if (t.count == 0) >> + seq_puts(seq, "No data\n"); >> + >> + return 0; >> +} >> + >> +static void slab_debugfs_stop(struct seq_file *seq, void *v) >> +{ >> + if (!v && t.max) { >> + free_loc_track(&t); >> + t.max = 0; >> + } >> +} >> + >> +static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos) >> +{ >> + loff_t *spos = v; >> + >> + if (*ppos < t.count) { >> + *spos = *spos + 1; >> + *ppos = *spos; >> + return spos; >> + } >> + >> + return NULL; >> +} >> + >> +static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos) >> +{ >> + struct kmem_cache_node *n; >> + struct kmem_cache *s; >> + enum track_item alloc; >> + int node; >> + loff_t *spos = kmalloc(sizeof(loff_t), GFP_KERNEL); >> + >> + s = seq->file->f_inode->i_private; >> + >> + if (!spos) >> + return NULL; >> + >> + if (*ppos == 0) { >> + >> + t.count = 0; >> + t.max = 0; >> + t.loc = NULL; >> + if (strcmp(seq->file->f_path.dentry->d_name.name, "alloc_traces") == 0) >> + alloc = TRACK_ALLOC; >> + else >> + alloc = TRACK_FREE; >> + >> + if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location), >> + GFP_KERNEL)) { >> + seq_puts(seq, "Out of memory\n"); >> + kfree(spos); >> + return ERR_PTR(-ENOMEM); >> + } >> + /* Push back cpu slabs */ >> + flush_all(s); >> + >> + for_each_kmem_cache_node(s, node, n) { >> + unsigned long flags; >> + struct page *page; >> + >> + if (!atomic_long_read(&n->nr_slabs)) >> + continue; >> + >> + spin_lock_irqsave(&n->list_lock, flags); >> + list_for_each_entry(page, &n->partial, slab_list) >> + process_slab(&t, s, page, alloc); >> + list_for_each_entry(page, &n->full, slab_list) >> + process_slab(&t, s, page, alloc); >> + spin_unlock_irqrestore(&n->list_lock, flags); >> + } >> + } >> + >> + if (*ppos < t.count) { >> + *spos = *ppos; >> + return spos; >> + } >> + >> + kfree(spos); >> + return NULL; >> +} >> + >> +static const struct seq_operations slab_debugfs_sops = { >> + .start = slab_debugfs_start, >> + .next = slab_debugfs_next, >> + .stop = slab_debugfs_stop, >> + .show = slab_debugfs_show >> +}; >> +DEFINE_SEQ_ATTRIBUTE(slab_debugfs); >> + >> +static void debugfs_slab_add(struct kmem_cache *s) >> +{ >> + const char *name; >> + struct dentry *slab_cache_dir; >> + int unmergeable = slab_unmergeable(s); >> + >> + if (unlikely(!slab_debugfs_root)) >> + return; >> + >> + if (!unmergeable && disable_higher_order_debug && >> + (slub_debug & DEBUG_METADATA_FLAGS)) >> + unmergeable = 1; >> + >> + if (unmergeable) { >> + /* >> + * Slabcache can never be merged so we can use the name proper. >> + * This is typically the case for debug situations. In that >> + * case we can catch duplicate names easily. >> + */ >> + slab_cache_dir = debugfs_lookup(s->name, slab_debugfs_root); >> + debugfs_remove_recursive(slab_cache_dir); >> + name = s->name; >> + } else { >> + /* >> + * Create a unique name for the slab as a target >> + * for the symlinks. >> + */ >> + name = create_unique_id(s); >> + } >> + >> + slab_cache_dir = debugfs_create_dir(name, slab_debugfs_root); >> + >> + debugfs_create_file("alloc_traces", 0400, >> + slab_cache_dir, s, &slab_debugfs_fops); >> + >> + debugfs_create_file("free_traces", 0400, >> + slab_cache_dir, s, &slab_debugfs_fops); >> +} >> + >> +void debugfs_slab_release(struct kmem_cache *s) >> +{ >> + debugfs_remove_recursive(debugfs_lookup(s->name, >> + slab_debugfs_root)); >> +} >> + >> +static int __init slab_debugfs_init(void) >> +{ >> + struct kmem_cache *s; >> + >> + slab_debugfs_root = debugfs_create_dir("slab", NULL); >> + >> + list_for_each_entry(s, &slab_caches, list) >> + if (s->flags & SLAB_STORE_USER) >> + debugfs_slab_add(s); >> + >> + return 0; >> + >> +} >> +__initcall(slab_debugfs_init); >> +#endif >> /* >> * The /proc/slabinfo ABI >> */ >> >