[Dovecot] memory allocation in new thread

[. .]

Hi! I have some problems with memory allocation.
I create new thread in cidir storage and call malloc(), and it fails to 
allocate even 1 byte.
What can cause this problem?

Dovecot vesrion is: 2.1.10 (130563b592c9+)

Sample code looks like this (I also link to pthread with: -pthread):

#define TEST_MALLOC() \
{ \
    void *p; \
     p = malloc(1); \
     if (!p) { \
         i_info("%s: malloc() failed", __FUNCTION__); \
     } else { \
         i_info("%s: malloc() succeeded", __FUNCTION__); \
         free(p); \
     } \
}

#include <pthread.h>

static void *test_pthread_malloc_func(void *data_)
{
     TEST_MALLOC();
     return NULL;
}

static void test_pthread_malloc()
{
     int ret;
     pthread_t tid;
     TEST_MALLOC();
     ret = pthread_create(&tid, NULL, test_pthread_malloc_func, NULL);
     if (ret) {
         i_info("failed to start thread");
     } else {
         pthread_join(tid, NULL);
     }
}

I call test_pthread_malloc() function.
It produces following output:

Oct 11 12:56:15 imap(guest): Info: test_pthread_malloc: malloc() succeeded
Oct 11 12:56:15 imap(guest): Info: test_pthread_malloc_func: malloc() failed