Re: 2.4.22 O_DIRECT memory leak?!?

[Magnus Andersson]

On Thu, Oct 09, 2003 at 04:37:52PM -0300, Marcelo Tosatti wrote:
> 
> 
> On Wed, 8 Oct 2003, Magnus Andersson wrote:
> 
> > Hello!
> > 
> > If I open one file a lot of times using the flag O_DIRECT,
> > memory seems to be be lost and never given back to the system.
> > This is happening on some kernels, see below for which ones I tried.
> > 
> > Attached program will produce this behavior, also attached 
> > is the output from vmstat while running the program.
> 
> Magnus,
> 
> That memory will be freed as soon as there's memory pressure so its not a 
> memory leak.

Ok. It's not a leak. But it looks like the memory never goes back to the system.
The kernel has killed some processes of mine, thats why I suspect this.

Attached are a program, malloc_mem.
Before running open_odirect, malloc_mem succeeds in allocating 450 000 000 bytes.
After running open_odirect, malloc_mem fails.

It is working on the 2.4.22-aa1 kernel, but not on 2.4.22

The test is run with this amount of memory, and no swap.

Memory: 515752k/524204k available (1593k kernel code, 8064k reserved, 334k data, 264k init, 0k highmem)

/Magnus
foo:~> ./malloc_mem 
All ok!
foo:~> ./open_odirect 
foo:~> ./malloc_mem
Could not malloc 450000000 bytes
foo:~>
#include <stdio.h>

#define MEM_SIZE 450000000

int main()
{
  int i;
  char *mem;
  
  mem = (char *)malloc(MEM_SIZE);

  if(mem == NULL) {
    printf("Could not malloc %d bytes\n", MEM_SIZE);
    exit(1);
  }

  memset(mem, 1, MEM_SIZE);

  printf("All ok!\n");
}
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 0  0      0 496804    940   7936    0    0     0     0  101     2  0  0 100  0
 0  0      0 496800    940   7940    0    0     0     0  101     6  0  0 100  0
 0  0      0 496800    940   7940    0    0     0     0  101     4  0  0 100  0
 0  0      0 496800    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 496800    940   7940    0    0     0     0  101     2  0  0 100  0
 1  0      0 438912    940   7940    0    0     0     0  104    14 71 28  1  0
 1  0      0 379896    940   7940    0    0     0     0  101     4 76 24  0  0
 1  0      0 320880    940   7940    0    0     0     0  101     4 78 22  0  0
 1  0      0 261868    940   7940    0    0     0     0  101     2 74 26  0  0
 1  0      0 202848    940   7940    0    0     0     0  101     2 77 23  0  0
 1  0      0 143836    940   7940    0    0     0     0  101     2 73 27  0  0
 1  0      0  84856    940   7940    0    0     0     0  101     8 76 24  0  0
 0  0      0 496716    940   7940    0    0     0     0  105    13 35 17 49  0
 0  0      0 496716    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 496716    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 496716    940   7940    0    0     0     0  107    16  0  0 100  0
 0  0      0 496716    940   7940    0    0     0     0  104    11  0  0 100  0
 1  0      0 461916    940   7940    0    0     0   128  137    27  0 17 83  0
 0  0      0 385028    940   7940    0    0     0     0  103     7  0 50 50  0
 0  0      0 385028    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 385028    940   7940    0    0     0     0  101     4  0  0 100  0
 0  0      0 385028    940   7940    0    0     0     0  107    20  0  0 100  0
 0  0      0 385028    940   7940    0    0     0    76  126    22  0  0 100  0
 0  0      0 385028    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 385028    940   7940    0    0     0     0  101     2  0  0 100  0
 0  0      0 385024    940   7944    0    0     0     0  101     2  0  0 100  0
 0  0      0 385024    940   7944    0    0     0     0  101     4  0  0 100  0
 0  0      0 385024    940   7944    0    0     0     0  101     4  0  0 100  0