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Message-ID: <6d1714a4-097e-4d8e-9f2a-907f031ac8f9@163.com>
Date: Mon, 7 Apr 2025 09:39:58 +0800
From: Liu Ye <liuyerd@....com>
To: hannes@...xchg.org, mhocko@...nel.org, roman.gushchin@...ux.dev,
shakeel.butt@...ux.dev, muchun.song@...ux.dev,
Andrew Morton <akpm@...ux-foundation.org>
Cc: willy@...radead.org, david@...hat.com, svetly.todorov@...verge.com,
vbabka@...e.cz, ran.xiaokai@....com.cn, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, cgroups@...r.kernel.org, linux-mm@...ck.org,
Liu Ye <liuye@...inos.cn>
Subject: Re: [PATCH v4] fs/proc/page: Refactoring to reduce code duplication.
Friendly ping.
在 2025/3/24 11:25, Liu Ye 写道:
> Friendly ping.
>
> 在 2025/3/18 14:32, Liu Ye 写道:
>> 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>
>>
>> ---
>> V4 : Update code remake patch.
>> V3 : Add a stub for page_cgroup_ino and remove the #ifdef CONFIG_MEMCG.
>> V2 : Use an enumeration to indicate the operation to be performed
>> to avoid passing functions.
>> ---
>> ---
>> fs/proc/page.c | 161 +++++++++++++------------------------
>> include/linux/memcontrol.h | 4 +
>> 2 files changed, 58 insertions(+), 107 deletions(-)
>>
>> diff --git a/fs/proc/page.c b/fs/proc/page.c
>> index 23fc771100ae..999af26c7298 100644
>> --- a/fs/proc/page.c
>> +++ b/fs/proc/page.c
>> @@ -22,6 +22,12 @@
>> #define KPMMASK (KPMSIZE - 1)
>> #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
>>
>> +enum kpage_operation {
>> + KPAGE_FLAGS,
>> + KPAGE_COUNT,
>> + KPAGE_CGROUP,
>> +};
>> +
>> static inline unsigned long get_max_dump_pfn(void)
>> {
>> #ifdef CONFIG_SPARSEMEM
>> @@ -37,19 +43,17 @@ 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 *page;
>> unsigned long src = *ppos;
>> unsigned long pfn;
>> ssize_t ret = 0;
>> + u64 info;
>>
>> pfn = src / KPMSIZE;
>> if (src & KPMMASK || count & KPMMASK)
>> @@ -59,24 +63,34 @@ 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) {
>> - struct folio *folio = page_folio(page);
>>
>> - if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
>> - mapcount = folio_precise_page_mapcount(folio, page);
>> - else
>> - mapcount = folio_average_page_mapcount(folio);
>> - }
>> -
>> - if (put_user(mapcount, out)) {
>> + if (page) {
>> + switch (op) {
>> + case KPAGE_FLAGS:
>> + info = stable_page_flags(page);
>> + break;
>> + case KPAGE_COUNT:
>> + if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
>> + info = folio_precise_page_mapcount(page_folio(page), page);
>> + else
>> + info = folio_average_page_mapcount(page_folio(page));
>> + break;
>> + case KPAGE_CGROUP:
>> + info = page_cgroup_ino(page);
>> + break;
>> + default:
>> + info = 0;
>> + break;
>> + }
>> + } else
>> + info = 0;
>> +
>> + if (put_user(info, out)) {
>> ret = -EFAULT;
>> break;
>> }
>> @@ -94,17 +108,23 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
>> return ret;
>> }
>>
>> +/* /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)
>> +{
>> + return kpage_read(file, buf, count, ppos, KPAGE_COUNT);
>> +}
>> +
>> static const struct proc_ops kpagecount_proc_ops = {
>> .proc_flags = PROC_ENTRY_PERMANENT,
>> .proc_lseek = mem_lseek,
>> .proc_read = kpagecount_read,
>> };
>>
>> -/* /proc/kpageflags - an array exposing page flags
>> - *
>> - * Each entry is a u64 representing the corresponding
>> - * physical page flags.
>> - */
>>
>> static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
>> {
>> @@ -225,47 +245,17 @@ u64 stable_page_flags(const struct page *page)
>> #endif
>>
>> return u;
>> -};
>> +}
>>
>> +/* /proc/kpageflags - an array exposing page flags
>> + *
>> + * Each entry is a u64 representing the corresponding
>> + * physical page flags.
>> + */
>> static ssize_t kpageflags_read(struct file *file, char __user *buf,
>> - size_t count, loff_t *ppos)
>> + size_t count, loff_t *ppos)
>> {
>> - const unsigned long max_dump_pfn = get_max_dump_pfn();
>> - u64 __user *out = (u64 __user *)buf;
>> - unsigned long src = *ppos;
>> - unsigned long pfn;
>> - ssize_t ret = 0;
>> -
>> - pfn = src / KPMSIZE;
>> - if (src & KPMMASK || count & KPMMASK)
>> - return -EINVAL;
>> - if (src >= max_dump_pfn * KPMSIZE)
>> - return 0;
>> - count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
>> -
>> - while (count > 0) {
>> - /*
>> - * TODO: ZONE_DEVICE support requires to identify
>> - * memmaps that were actually initialized.
>> - */
>> - struct page *page = pfn_to_online_page(pfn);
>> -
>> - if (put_user(stable_page_flags(page), out)) {
>> - ret = -EFAULT;
>> - break;
>> - }
>> -
>> - pfn++;
>> - out++;
>> - count -= KPMSIZE;
>> -
>> - cond_resched();
>> - }
>> -
>> - *ppos += (char __user *)out - buf;
>> - if (!ret)
>> - ret = (char __user *)out - buf;
>> - return ret;
>> + return kpage_read(file, buf, count, ppos, KPAGE_FLAGS);
>> }
>>
>> static const struct proc_ops kpageflags_proc_ops = {
>> @@ -276,53 +266,10 @@ 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)
>> + size_t count, loff_t *ppos)
>> {
>> - 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 ino;
>> -
>> - pfn = src / KPMSIZE;
>> - if (src & KPMMASK || count & KPMMASK)
>> - return -EINVAL;
>> - if (src >= max_dump_pfn * KPMSIZE)
>> - return 0;
>> - count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
>> -
>> - while (count > 0) {
>> - /*
>> - * TODO: ZONE_DEVICE support requires to identify
>> - * memmaps that were actually initialized.
>> - */
>> - ppage = pfn_to_online_page(pfn);
>> -
>> - if (ppage)
>> - ino = page_cgroup_ino(ppage);
>> - else
>> - ino = 0;
>> -
>> - if (put_user(ino, out)) {
>> - ret = -EFAULT;
>> - break;
>> - }
>> -
>> - pfn++;
>> - out++;
>> - count -= KPMSIZE;
>> -
>> - cond_resched();
>> - }
>> -
>> - *ppos += (char __user *)out - buf;
>> - if (!ret)
>> - ret = (char __user *)out - buf;
>> - return ret;
>> + return kpage_read(file, buf, count, ppos, KPAGE_CGROUP);
>> }
>> -
>> static const struct proc_ops kpagecgroup_proc_ops = {
>> .proc_flags = PROC_ENTRY_PERMANENT,
>> .proc_lseek = mem_lseek,
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 53364526d877..5264d148bdd9 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -1793,6 +1793,10 @@ 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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