mprotect() failed: Cannot allocate memory

[Paweł Sikora]

Dnia 21-04-2010 o 11:22:19 Yann Droneaud <yann@droneaud.fr> napisał(a):

> Le mercredi 21 avril 2010 à 01:44 +0200, Paweł Sikora a écrit :
>> On Wednesday 21 April 2010 01:17:22 Mike Frysinger wrote:
>> > On Tuesday 20 April 2010 19:05:20 Paweł Sikora wrote:
>> > > i'm trying to debug an ugly application with ElectricFence.
>> >
>> > electricfence does a lot of ugly memory tricks to do its thing,  
>> including,
>> > but not limited to, overriding memory related symbols.  best to seek  
>> help
>> > from the electricfence authors.
>>
>> so, let's avoid EF and run following test:
>>
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <unistd.h>
>> #include <sys/mman.h>
>>
>> void* my_alloc( size_t n )
>> {
>>         size_t ps = getpagesize();
>>         printf( "request for %Zd bytes => ", n );
>>         /* alloc PAGE_SIZE + n */
>>         char* p = mmap( 0, ps + n, PROT_READ | PROT_WRITE, MAP_SHARED |
>> MAP_ANONYMOUS, -1, 0 );
>>         if ( p == MAP_FAILED )
>>                 __builtin_abort();
>>         /* block guard page */
>>         int rc = mprotect( p, ps, PROT_NONE );
>>         if ( rc != 0 )
>>                 __builtin_abort();
>>         char* q = p + ps;
>>         printf( "guard page @ %p, allocated region @ %p\n", p, q );
>>         return q;
>> }
>>
>> int main()
>> {
>>         #define N 100
>>         size_t NN = 4*100*100;
>>         size_t kmax = 100;
>>         int i;
>>
>>         double **bm = (double **)my_alloc( NN * sizeof( double* ) );
>>         for( i = 0; i < NN; ++i )
>>         {
>>                 bm[ i ] = (double*)my_alloc( kmax * sizeof( double ) );
>>         }
>>         // leak...
>>         return 0;
>> }
>>
>> and the result is...
>>
>> (...)
>> mmap(NULL, 4896, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0)  
>> =
>> 0x7f5fd97df000
>> mprotect(0x7f5fd97df000, 4096, PROT_NONE) = -1 ENOMEM (Cannot allocate  
>> memory)
>
> Have you checked available memory on your system ? Or user limit ?
>
> You test program is going to allocate
>  79 + 1 pages for bm
>  1 + 1 for each double arrays (x 40000)
>
> So in the end your program is allocating 80080 pages, so about
> 312MBytes.
>
> It not that big for a 64bits system.
>
> Check limits such as
> -d	the maximum size of a process's data segment
> -l	the maximum size a process may lock into memory
> -m	the maximum resident set size

$ ulimit -a
-t: cpu time (seconds)         unlimited
-f: file size (blocks)         unlimited
-d: data seg size (kbytes)     unlimited
-s: stack size (kbytes)        8192
-c: core file size (blocks)    0
-m: resident set size (kbytes) unlimited
-u: processes                  unlimited
-n: file descriptors           1024
-l: locked-in-memory size (kb) 64
-v: address space (kb)         unlimited
-x: file locks                 unlimited
-i: pending signals            64024
-q: bytes in POSIX msg queues  819200
-e: max nice                   0
-r: max rt priority            0

$ free -m
              total       used       free     shared    buffers     cached
Mem:          8004       1779       6224          0         36       1228
-/+ buffers/cache:        514       7489
Swap:        15625          0      15625


imho the testcase has enough hardware resources.