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Message-ID: <dd2e281e-0dea-8acf-30dc-b85d0d438cf3@c-s.fr>
Date: Wed, 17 Jan 2018 12:11:16 +0100
From: Christophe LEROY <christophe.leroy@....fr>
To: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>,
Scott Wood <oss@...error.net>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] powerpc/mm: Fix growth direction for hugepages mmaps
with slice
Le 17/01/2018 à 04:19, Aneesh Kumar K.V a écrit :
>
>
> On 01/16/2018 10:18 PM, Christophe LEROY wrote:
>>
>>
>> Le 16/01/2018 à 17:03, Aneesh Kumar K.V a écrit :
>>> Christophe Leroy <christophe.leroy@....fr> writes:
>>>
>>>> An application running with libhugetlbfs fails to allocate
>>>> additional pages to HEAP due to the hugemap being done
>>>> inconditionally as topdown mapping:
>>>>
>>>> mmap(0x10080000, 1572864, PROT_READ|PROT_WRITE,
>>>> MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0) = 0x73e80000
>>>> [...]
>>>> mmap(0x74000000, 1048576, PROT_READ|PROT_WRITE,
>>>> MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d80000
>>>> munmap(0x73d80000, 1048576) = 0
>>>> [...]
>>>> mmap(0x74000000, 1572864, PROT_READ|PROT_WRITE,
>>>> MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d00000
>>>> munmap(0x73d00000, 1572864) = 0
>>>> [...]
>>>> mmap(0x74000000, 1572864, PROT_READ|PROT_WRITE,
>>>> MAP_PRIVATE|MAP_ANONYMOUS|0x40000, -1, 0x180000) = 0x73d00000
>>>> munmap(0x73d00000, 1572864) = 0
>>>> [...]
>>>>
>>>
>>> Can you explain the failure details above. I am not sure I understand
>>> what to read from the above output.
>>
>> libhugetlbfs first requests an area of size 1.5Mbytes, at address
>> 0x10080000
>> mmap() returns an area at address 0x73e80000
>>
>> Then libhugetlbfs requests an additional area on top of that, ie at
>> address 0x74000000, to expand the heap.
>> But mmap() returns an area at address 0x73d80000, ie under the
>> previous area.
>>
>
>
> Can you share the test details?. Why does it not fail on book3s64? We
> use topdown search with book3s64.
I don't know about book3s64, I only have 8xx.
Here is my test app:
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
char *p;
char buf[16384];
char filename[32];
int fd, r;
sprintf(filename, "/proc/%d/maps", getpid());
fd = open(filename, O_RDONLY);
r = read(fd, buf, sizeof(buf));
close(fd);
buf[r] = 0;
fputs(buf, stderr);
fputc('\n', stderr);
p = malloc(1024*1024);
fprintf(stderr, "\nAllocated 1Mbytes at %p\n\n", p);
p = malloc(1024*1024);
fprintf(stderr, "\nAllocated 1Mbytes at %p\n\n", p);
p = malloc(1024*1024);
fprintf(stderr, "\nAllocated 1Mbytes at %p\n\n", p);
fd = open(filename, O_RDONLY);
r = read(fd, buf, sizeof(buf));
close(fd);
buf[r] = 0;
fputs(buf, stderr);
fputc('\n', stderr);
exit(0);
}
It is linked with -lhugetlbfs (version 2.20)
My 8xx board is configured with 64 huge pages, default size 512k:
root@...ip:~# cat /proc/meminfo
MemTotal: 123664 kB
MemFree: 58464 kB
MemAvailable: 67904 kB
Buffers: 0 kB
Cached: 14480 kB
SwapCached: 0 kB
Active: 11616 kB
Inactive: 7872 kB
Active(anon): 7584 kB
Inactive(anon): 240 kB
Active(file): 4032 kB
Inactive(file): 7632 kB
Unevictable: 2560 kB
Mlocked: 2560 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 7568 kB
Mapped: 7456 kB
Shmem: 736 kB
Slab: 7456 kB
SReclaimable: 3120 kB
SUnreclaim: 4336 kB
KernelStack: 568 kB
PageTables: 1024 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 45440 kB
Committed_AS: 38880 kB
VmallocTotal: 866304 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HugePages_Total: 64
HugePages_Free: 64
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 512 kB
Without the patch, my test app gives the following results: as you can
see, second and third malloc returns address which is not in a hugepage.
strace shows that libhugetlbfs fallsback on regular mmap because
hugepage has not been allocated at the requested address.
root@...ip:~# HUGETLB_MORECORE=yes ./huge_malloc_test
00100000-00108000 r-xp 00000000 00:00 0 [vdso]
0fde4000-0fde8000 r-xp 00000000 00:0f 168 /lib/libdl-2.23.so
0fde8000-0fe00000 ---p 00004000 00:0f 168 /lib/libdl-2.23.so
0fe00000-0fe04000 r--p 0000c000 00:0f 168 /lib/libdl-2.23.so
0fe04000-0fe08000 rwxp 00010000 00:0f 168 /lib/libdl-2.23.so
0fe18000-0ff88000 r-xp 00000000 00:0f 191 /lib/libc-2.23.so
0ff88000-0ffa4000 ---p 00170000 00:0f 191 /lib/libc-2.23.so
0ffa4000-0ffa8000 r--p 0017c000 00:0f 191 /lib/libc-2.23.so
0ffa8000-0ffac000 rwxp 00180000 00:0f 191 /lib/libc-2.23.so
0ffac000-0ffb0000 rwxp 00000000 00:00 0
0ffc0000-0ffd4000 r-xp 00000000 00:0f 90 /lib/libhugetlbfs.so
0ffd4000-0ffe0000 ---p 00014000 00:0f 90 /lib/libhugetlbfs.so
0ffe0000-0ffe4000 rwxp 00010000 00:0f 90 /lib/libhugetlbfs.so
0ffe4000-0fff0000 rwxp 00000000 00:00 0
10000000-10004000 r-xp 00000000 00:0f 3076 /root/huge_malloc_test
10010000-10014000 rwxp 00000000 00:0f 3076 /root/huge_malloc_test
77940000-77964000 r-xp 00000000 00:0f 171 /lib/ld-2.23.so
7797c000-77980000 r--p 0002c000 00:0f 171 /lib/ld-2.23.so
77980000-77984000 rwxp 00030000 00:0f 171 /lib/ld-2.23.so
7fa58000-7fa7c000 rw-p 00000000 00:00 0 [stack]
libhugetlbfs: WARNING: Heap originates at 0x73e80000 instead of 0x10080000
Allocated 1Mbytes at 0x73e80008
libhugetlbfs: WARNING: New heap segment mapped at 0x73d80000 instead of
0x74000000
Allocated 1Mbytes at 0x777fc008
libhugetlbfs: WARNING: New heap segment mapped at 0x73d00000 instead of
0x74000000
Allocated 1Mbytes at 0x776b8008
00100000-00108000 r-xp 00000000 00:00 0 [vdso]
0fde4000-0fde8000 r-xp 00000000 00:0f 168 /lib/libdl-2.23.so
0fde8000-0fe00000 ---p 00004000 00:0f 168 /lib/libdl-2.23.so
0fe00000-0fe04000 r--p 0000c000 00:0f 168 /lib/libdl-2.23.so
0fe04000-0fe08000 rwxp 00010000 00:0f 168 /lib/libdl-2.23.so
0fe18000-0ff88000 r-xp 00000000 00:0f 191 /lib/libc-2.23.so
0ff88000-0ffa4000 ---p 00170000 00:0f 191 /lib/libc-2.23.so
0ffa4000-0ffa8000 r--p 0017c000 00:0f 191 /lib/libc-2.23.so
0ffa8000-0ffac000 rwxp 00180000 00:0f 191 /lib/libc-2.23.so
0ffac000-0ffb0000 rwxp 00000000 00:00 0
0ffc0000-0ffd4000 r-xp 00000000 00:0f 90 /lib/libhugetlbfs.so
0ffd4000-0ffe0000 ---p 00014000 00:0f 90 /lib/libhugetlbfs.so
0ffe0000-0ffe4000 rwxp 00010000 00:0f 90 /lib/libhugetlbfs.so
0ffe4000-0fff0000 rwxp 00000000 00:00 0
10000000-10004000 r-xp 00000000 00:0f 3076 /root/huge_malloc_test
10010000-10014000 rwxp 00000000 00:0f 3076 /root/huge_malloc_test
73e80000-74000000 rw-p 00000000 00:0b 98386 /anon_hugepage (deleted)
776b8000-77940000 rw-p 00000000 00:00 0
77940000-77964000 r-xp 00000000 00:0f 171 /lib/ld-2.23.so
7797c000-77980000 r--p 0002c000 00:0f 171 /lib/ld-2.23.so
77980000-77984000 rwxp 00030000 00:0f 171 /lib/ld-2.23.so
7fa58000-7fa7c000 rw-p 00000000 00:00 0 [stack]
With the patch applied, it works properly, each malloc get an address
within the hugepage space.
root@...ip:~# HUGETLB_MORECORE=yes ./huge_malloc_test
00100000-00108000 r-xp 00000000 00:00 0 [vdso]
0fde4000-0fde8000 r-xp 00000000 00:0f 168 /lib/libdl-2.23.so
0fde8000-0fe00000 ---p 00004000 00:0f 168 /lib/libdl-2.23.so
0fe00000-0fe04000 r--p 0000c000 00:0f 168 /lib/libdl-2.23.so
0fe04000-0fe08000 rwxp 00010000 00:0f 168 /lib/libdl-2.23.so
0fe18000-0ff88000 r-xp 00000000 00:0f 191 /lib/libc-2.23.so
0ff88000-0ffa4000 ---p 00170000 00:0f 191 /lib/libc-2.23.so
0ffa4000-0ffa8000 r--p 0017c000 00:0f 191 /lib/libc-2.23.so
0ffa8000-0ffac000 rwxp 00180000 00:0f 191 /lib/libc-2.23.so
0ffac000-0ffb0000 rwxp 00000000 00:00 0
0ffc0000-0ffd4000 r-xp 00000000 00:0f 90 /lib/libhugetlbfs.so
0ffd4000-0ffe0000 ---p 00014000 00:0f 90 /lib/libhugetlbfs.so
0ffe0000-0ffe4000 rwxp 00010000 00:0f 90 /lib/libhugetlbfs.so
0ffe4000-0fff0000 rwxp 00000000 00:00 0
10000000-10004000 r-xp 00000000 00:0f 3076 /root/huge_malloc_test
10010000-10014000 rwxp 00000000 00:0f 3076 /root/huge_malloc_test
77884000-778a8000 r-xp 00000000 00:0f 171 /lib/ld-2.23.so
778c0000-778c4000 r--p 0002c000 00:0f 171 /lib/ld-2.23.so
778c4000-778c8000 rwxp 00030000 00:0f 171 /lib/ld-2.23.so
7ff98000-7ffbc000 rw-p 00000000 00:00 0 [stack]
libhugetlbfs: WARNING: Heap originates at 0x30000000 instead of 0x10080000
Allocated 1Mbytes at 0x30000008
Allocated 1Mbytes at 0x30100010
Allocated 1Mbytes at 0x30200018
00100000-00108000 r-xp 00000000 00:00 0 [vdso]
0fde4000-0fde8000 r-xp 00000000 00:0f 168 /lib/libdl-2.23.so
0fde8000-0fe00000 ---p 00004000 00:0f 168 /lib/libdl-2.23.so
0fe00000-0fe04000 r--p 0000c000 00:0f 168 /lib/libdl-2.23.so
0fe04000-0fe08000 rwxp 00010000 00:0f 168 /lib/libdl-2.23.so
0fe18000-0ff88000 r-xp 00000000 00:0f 191 /lib/libc-2.23.so
0ff88000-0ffa4000 ---p 00170000 00:0f 191 /lib/libc-2.23.so
0ffa4000-0ffa8000 r--p 0017c000 00:0f 191 /lib/libc-2.23.so
0ffa8000-0ffac000 rwxp 00180000 00:0f 191 /lib/libc-2.23.so
0ffac000-0ffb0000 rwxp 00000000 00:00 0
0ffc0000-0ffd4000 r-xp 00000000 00:0f 90 /lib/libhugetlbfs.so
0ffd4000-0ffe0000 ---p 00014000 00:0f 90 /lib/libhugetlbfs.so
0ffe0000-0ffe4000 rwxp 00010000 00:0f 90 /lib/libhugetlbfs.so
0ffe4000-0fff0000 rwxp 00000000 00:00 0
10000000-10004000 r-xp 00000000 00:0f 3076 /root/huge_malloc_test
10010000-10014000 rwxp 00000000 00:0f 3076 /root/huge_malloc_test
30000000-30180000 rw-p 00000000 00:0b 7321 /anon_hugepage (deleted)
30180000-30280000 rw-p 00180000 00:0b 7322 /anon_hugepage (deleted)
30280000-30380000 rw-p 00280000 00:0b 7323 /anon_hugepage (deleted)
77884000-778a8000 r-xp 00000000 00:0f 171 /lib/ld-2.23.so
778c0000-778c4000 r--p 0002c000 00:0f 171 /lib/ld-2.23.so
778c4000-778c8000 rwxp 00030000 00:0f 171 /lib/ld-2.23.so
7ff98000-7ffbc000 rw-p 00000000 00:00 0 [stack]
Christophe
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