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Wed, 17 Feb 2021 06:40:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org DAFDFC433C6 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] mm: slub: Convert sys slab alloc_calls, free_calls to bin attribute 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 Cc: vinmenon@codeaurora.org References: <1610443287-23933-1-git-send-email-faiyazm@codeaurora.org> From: Faiyaz Mohammed Message-ID: <7c2e2e62-8589-f9ca-1933-7faccc87bccd@codeaurora.org> Date: Wed, 17 Feb 2021 12:10:47 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Vlastimil, On 1/13/2021 9:35 PM, Vlastimil Babka wrote: > On 1/12/21 10:21 AM, Faiyaz Mohammed wrote: >> Reading the sys slab alloc_calls, free_calls returns the available object >> owners, but the size of this file is limited to PAGE_SIZE >> because of the limitation of sysfs attributes, it is returning the >> partial owner info, which is not sufficient to debug/account the slab >> memory and alloc_calls output is not matching with /proc/slabinfo. >> >> To remove the PAGE_SIZE limitation converted the sys slab >> alloc_calls, free_calls to bin attribute. >> >> Signed-off-by: Faiyaz Mohammed >> --- >> mm/slub.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++-------------- >> 1 file changed, 47 insertions(+), 14 deletions(-) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index b52384e..8744e5ec 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -4710,13 +4710,14 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s, >> } >> >> static int list_locations(struct kmem_cache *s, char *buf, >> - enum track_item alloc) >> + loff_t offset, enum track_item alloc) >> { >> int len = 0; >> unsigned long i; >> struct loc_track t = { 0, 0, NULL }; >> int node; >> struct kmem_cache_node *n; >> + static unsigned int previous_read_count; > > Hmm static? What about parallel reads from different files? I guess you'll have > to somehow employ the offset parameter here and it won't be pretty, because you > are still printing free text and not some fixed-size binary chunks where seeking > is simple. To avoid static, I have used small logic by fixing track max length and tracks per page. Please find patch v2. > Also it's wasteful to to repeat the data gathering for each pritned page, you'd > need a mechanism that allows holding private data between printing out the > pages. If bin_attribute doesn't have that, you'd need e.g. seq_file which we use > for /proc/pid/(s)maps etc.>I think seq_file implementation is not feasible with sysfs and I didn't find any example in kernel. If we want to use seq_file than I guess we have to move slab in debugfs. >> unsigned long *map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL); > > This line doesn't exist since 90e9f6a66c78f in v5.6-rc1, is the patch based on > an old kernel? > Updated the patch v2. >> if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location), >> @@ -4742,11 +4743,9 @@ static int list_locations(struct kmem_cache *s, char *buf, >> spin_unlock_irqrestore(&n->list_lock, flags); >> } >> >> - for (i = 0; i < t.count; i++) { >> + for (i = previous_read_count; i < t.count; i++) { >> struct location *l = &t.loc[i]; >> >> - if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100) >> - break; >> len += sprintf(buf + len, "%7ld ", l->count); >> >> if (l->addr) >> @@ -4784,12 +4783,20 @@ static int list_locations(struct kmem_cache *s, char *buf, >> nodemask_pr_args(&l->nodes)); >> >> len += sprintf(buf + len, "\n"); >> + >> + if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100) { >> + previous_read_count = i + 1; >> + break; >> + } >> } >> >> + if ((offset != 0) && ((i >= t.count) || (previous_read_count > t.count))) { >> + previous_read_count = 0; >> + len = 0; >> + } else if (!t.count) >> + len += sprintf(buf, "No data\n"); >> free_loc_track(&t); >> bitmap_free(map); >> - if (!t.count) >> - len += sprintf(buf, "No data\n"); >> return len; >> } >> >> @@ -5180,6 +5187,7 @@ static int any_slab_objects(struct kmem_cache *s) >> >> struct slab_attribute { >> struct attribute attr; >> + struct bin_attribute bin_attr; >> ssize_t (*show)(struct kmem_cache *s, char *buf); >> ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count); >> }; >> @@ -5192,6 +5200,12 @@ struct slab_attribute { >> static struct slab_attribute _name##_attr = \ >> __ATTR(_name, 0600, _name##_show, _name##_store) >> >> +#define SLAB_BIN_ATTR_RO(_name) \ >> + static struct slab_attribute _name##_attr = { \ >> + .bin_attr = \ >> + __BIN_ATTR_RO(_name, 0) \ >> + } \ >> + >> static ssize_t slab_size_show(struct kmem_cache *s, char *buf) >> { >> return sprintf(buf, "%u\n", s->size); >> @@ -5535,21 +5549,33 @@ static ssize_t validate_store(struct kmem_cache *s, >> } >> SLAB_ATTR(validate); >> >> -static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf) >> +static ssize_t alloc_calls_read(struct file *filp, struct kobject *kobj, >> + struct bin_attribute *bin_attr, char *buf, >> + loff_t offset, size_t count) >> { >> + struct kmem_cache *s; >> + >> + s = to_slab(kobj); >> if (!(s->flags & SLAB_STORE_USER)) >> return -ENOSYS; >> - return list_locations(s, buf, TRACK_ALLOC); >> + >> + return list_locations(s, buf, offset, TRACK_ALLOC); >> } >> -SLAB_ATTR_RO(alloc_calls); >> +SLAB_BIN_ATTR_RO(alloc_calls); >> >> -static ssize_t free_calls_show(struct kmem_cache *s, char *buf) >> +static ssize_t free_calls_read(struct file *filp, struct kobject *kobj, >> + struct bin_attribute *bin_attr, char *buf, >> + loff_t offset, size_t count) >> { >> + struct kmem_cache *s; >> + >> + s = to_slab(kobj); >> if (!(s->flags & SLAB_STORE_USER)) >> return -ENOSYS; >> - return list_locations(s, buf, TRACK_FREE); >> + >> + return list_locations(s, buf, offset, TRACK_FREE); >> } >> -SLAB_ATTR_RO(free_calls); >> +SLAB_BIN_ATTR_RO(free_calls); >> #endif /* CONFIG_SLUB_DEBUG */ >> >> #ifdef CONFIG_FAILSLAB >> @@ -5694,6 +5720,14 @@ STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node); >> STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain); >> #endif /* CONFIG_SLUB_STATS */ >> >> + >> +static struct bin_attribute *slab_bin_attrs[] = { >> +#ifdef CONFIG_SLUB_DEBUG >> + &alloc_calls_attr.bin_attr, >> + &free_calls_attr.bin_attr, >> +#endif >> +}; >> + >> static struct attribute *slab_attrs[] = { >> &slab_size_attr.attr, >> &object_size_attr.attr, >> @@ -5722,8 +5756,6 @@ 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, >> @@ -5769,6 +5801,7 @@ static struct attribute *slab_attrs[] = { >> >> static const struct attribute_group slab_attr_group = { >> .attrs = slab_attrs, >> + .bin_attrs = slab_bin_attrs, >> }; >> >> static ssize_t slab_attr_show(struct kobject *kobj, >> >