Re: [PATCH v1 2/3] fs/proc/page.c: allow inspection of last section and fix end detection

From: kbuild test robot
Date: Mon Dec 09 2019 - 19:47:41 EST


Hi David,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on linux/master v5.5-rc1 next-20191209]
[cannot apply to mmotm/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url: https://github.com/0day-ci/linux/commits/David-Hildenbrand/mm-fix-max_pfn-not-falling-on-section-boundary/20191210-071011
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 6794862a16ef41f753abd75c03a152836e4c8028
config: um-x86_64_defconfig (attached as .config)
compiler: gcc-7 (Debian 7.5.0-1) 7.5.0
reproduce:
# save the attached .config to linux build tree
make ARCH=um SUBARCH=x86_64

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>

All error/warnings (new ones prefixed by >>):

In file included from include/asm-generic/bug.h:19:0,
from ./arch/um/include/generated/asm/bug.h:1,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/mm.h:9,
from include/linux/memblock.h:13,
from fs/proc/page.c:2:
fs/proc/page.c: In function 'kpagecount_read':
>> fs/proc/page.c:32:55: error: 'PAGES_PER_SECTION' undeclared (first use in this function); did you mean 'USEC_PER_SEC'?
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^
include/linux/kernel.h:62:46: note: in definition of macro '__round_mask'
#define __round_mask(x, y) ((__typeof__(x))((y)-1))
^
>> fs/proc/page.c:32:37: note: in expansion of macro 'round_up'
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^~~~~~~~
fs/proc/page.c:32:55: note: each undeclared identifier is reported only once for each function it appears in
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^
include/linux/kernel.h:62:46: note: in definition of macro '__round_mask'
#define __round_mask(x, y) ((__typeof__(x))((y)-1))
^
>> fs/proc/page.c:32:37: note: in expansion of macro 'round_up'
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^~~~~~~~
fs/proc/page.c: In function 'kpageflags_read':
fs/proc/page.c:212:55: error: 'PAGES_PER_SECTION' undeclared (first use in this function); did you mean 'USEC_PER_SEC'?
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^
include/linux/kernel.h:62:46: note: in definition of macro '__round_mask'
#define __round_mask(x, y) ((__typeof__(x))((y)-1))
^
fs/proc/page.c:212:37: note: in expansion of macro 'round_up'
const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
^~~~~~~~

vim +32 fs/proc/page.c

> 2 #include <linux/memblock.h>
3 #include <linux/compiler.h>
4 #include <linux/fs.h>
5 #include <linux/init.h>
6 #include <linux/ksm.h>
7 #include <linux/mm.h>
8 #include <linux/mmzone.h>
9 #include <linux/huge_mm.h>
10 #include <linux/proc_fs.h>
11 #include <linux/seq_file.h>
12 #include <linux/hugetlb.h>
13 #include <linux/memcontrol.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/page_idle.h>
16 #include <linux/kernel-page-flags.h>
17 #include <linux/uaccess.h>
18 #include "internal.h"
19
20 #define KPMSIZE sizeof(u64)
21 #define KPMMASK (KPMSIZE - 1)
22 #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
23
24 /* /proc/kpagecount - an array exposing page counts
25 *
26 * Each entry is a u64 representing the corresponding
27 * physical page count.
28 */
29 static ssize_t kpagecount_read(struct file *file, char __user *buf,
30 size_t count, loff_t *ppos)
31 {
> 32 const unsigned long max_dump_pfn = round_up(max_pfn, PAGES_PER_SECTION);
33 u64 __user *out = (u64 __user *)buf;
34 struct page *ppage;
35 unsigned long src = *ppos;
36 unsigned long pfn;
37 ssize_t ret = 0;
38 u64 pcount;
39
40 pfn = src / KPMSIZE;
41 if (src & KPMMASK || count & KPMMASK)
42 return -EINVAL;
43 if (src >= max_dump_pfn * KPMSIZE)
44 return 0;
45 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
46
47 while (count > 0) {
48 /*
49 * TODO: ZONE_DEVICE support requires to identify
50 * memmaps that were actually initialized.
51 */
52 ppage = pfn_to_online_page(pfn);
53
54 if (!ppage || PageSlab(ppage) || page_has_type(ppage))
55 pcount = 0;
56 else
57 pcount = page_mapcount(ppage);
58
59 if (put_user(pcount, out)) {
60 ret = -EFAULT;
61 break;
62 }
63
64 pfn++;
65 out++;
66 count -= KPMSIZE;
67
68 cond_resched();
69 }
70
71 *ppos += (char __user *)out - buf;
72 if (!ret)
73 ret = (char __user *)out - buf;
74 return ret;
75 }
76

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