Messages in this thread | | | From | Paweł Sikora <> | Subject | Re: mprotect() failed: Cannot allocate memory | Date | Wed, 21 Apr 2010 01:44:18 +0200 |
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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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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