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Message-ID: <0693eb9c-226b-4233-9d60-dcd65967222a@163.com>
Date: Tue, 18 Mar 2025 10:00:18 +0800
From: Liu Ye <liuyerd@....com>
To: David Hildenbrand <david@...hat.com>, akpm@...ux-foundation.org
Cc: willy@...radead.org, ran.xiaokai@....com.cn, dan.carpenter@...aro.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Liu Ye <liuye@...inos.cn>
Subject: Re: [PATCH v2] fs/proc/page: Refactoring to reduce code duplication.
在 2025/3/17 18:24, David Hildenbrand 写道:
> On 17.03.25 11:07, Liu Ye wrote:
>> From: Liu Ye <liuye@...inos.cn>
>>
>> The function kpageflags_read and kpagecgroup_read is quite similar
>> to kpagecount_read. Consider refactoring common code into a helper
>> function to reduce code duplication.
>>
>> Signed-off-by: Liu Ye <liuye@...inos.cn>
>>
>> ---
>> V2 : Use an enumeration to indicate the operation to be performed
>> to avoid passing functions.
>> ---
>> ---
>> fs/proc/page.c | 166 +++++++++++++++++--------------------------------
>> 1 file changed, 58 insertions(+), 108 deletions(-)
>>
>> diff --git a/fs/proc/page.c b/fs/proc/page.c
>> index a55f5acefa97..66f454330a87 100644
>> --- a/fs/proc/page.c
>> +++ b/fs/proc/page.c
>> @@ -22,6 +22,14 @@
>> #define KPMMASK (KPMSIZE - 1)
>> #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
>> +enum kpage_operation {
>> + KPAGE_FLAGS,
>> + KPAGE_COUNT,
>> +#ifdef CONFIG_MEMCG
>> + KPAGE_CGROUP,
>> +#endif
>> +};
>> +
>> static inline unsigned long get_max_dump_pfn(void)
>> {
>> #ifdef CONFIG_SPARSEMEM
>> @@ -37,19 +45,17 @@ static inline unsigned long get_max_dump_pfn(void)
>> #endif
>> }
>> -/* /proc/kpagecount - an array exposing page mapcounts
>> - *
>> - * Each entry is a u64 representing the corresponding
>> - * physical page mapcount.
>> - */
>> -static ssize_t kpagecount_read(struct file *file, char __user *buf,
>> - size_t count, loff_t *ppos)
>> +static ssize_t kpage_read(struct file *file, char __user *buf,
>> + size_t count, loff_t *ppos,
>> + enum kpage_operation op)
>> {
>> const unsigned long max_dump_pfn = get_max_dump_pfn();
>> u64 __user *out = (u64 __user *)buf;
>> + struct page *ppage;
>> unsigned long src = *ppos;
>> unsigned long pfn;
>> ssize_t ret = 0;
>> + u64 info;
>> pfn = src / KPMSIZE;
>> if (src & KPMMASK || count & KPMMASK)
>> @@ -59,19 +65,29 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
>> count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
>> while (count > 0) {
>> - struct page *page;
>> - u64 mapcount = 0;
>> -
>> - /*
>> - * TODO: ZONE_DEVICE support requires to identify
>> - * memmaps that were actually initialized.
>> - */
>> - page = pfn_to_online_page(pfn);
>> - if (page)
>> - mapcount = folio_precise_page_mapcount(page_folio(page),
>> - page);
>> -
>> - if (put_user(mapcount, out)) {
>> + ppage = pfn_to_online_page(pfn);
>> +
>> + if (ppage) {
>> + switch (op) {
>> + case KPAGE_FLAGS:
>> + info = stable_page_flags(ppage);
>> + break;
>> + case KPAGE_COUNT:
>> + info = folio_precise_page_mapcount(page_folio(ppage), ppage);
>> + break;
>> +#ifdef CONFIG_MEMCG
>> + case KPAGE_CGROUP:
>> + info = page_cgroup_ino(ppage);
>> + break;
>> +#endif
>
> In general, LGTM.
>
> I do wonder if we should just get rid of the two "#ifdef CONFIG_MEMCG" by adding
> a stub for page_cgroup_ino().
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 57664e2a8fb7b..24248f4dcc971 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1788,6 +1788,11 @@ static inline void count_objcg_events(struct obj_cgroup *objcg,
> {
> }
>
> +static inline ino_t page_cgroup_ino(struct page *page)
> +{
> + return 0;
> +}
> +
> #endif /* CONFIG_MEMCG */
>
> #if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)
>
>
Agreed. I’ll add a stub for page_cgroup_ino() and remove the #ifdef CONFIG_MEMCG.
like this.
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 66f454330a87..cbadbf9568a1 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -25,9 +25,7 @@
enum kpage_operation {
KPAGE_FLAGS,
KPAGE_COUNT,
-#ifdef CONFIG_MEMCG
KPAGE_CGROUP,
-#endif
};
static inline unsigned long get_max_dump_pfn(void)
@@ -75,11 +73,9 @@ static ssize_t kpage_read(struct file *file, char __user *buf,
case KPAGE_COUNT:
info = folio_precise_page_mapcount(page_folio(ppage), ppage);
break;
-#ifdef CONFIG_MEMCG
case KPAGE_CGROUP:
info = page_cgroup_ino(ppage);
break;
-#endif
default:
info = 0;
break;
@@ -262,7 +258,6 @@ static const struct proc_ops kpageflags_proc_ops = {
};
#ifdef CONFIG_MEMCG
-
static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6e74b8254d9b..e806e2ebf5b8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1794,6 +1794,10 @@ static inline void count_objcg_events(struct obj_cgroup *objcg,
{
}
+static inline ino_t page_cgroup_ino(struct page *page)
+{
+ return 0;
+}
#endif /* CONFIG_MEMCG */
#if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)
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