Cleanup if allocuvm fails to alloc. Add a test.

This commit is contained in:
Austin Clements 2010-08-31 21:49:49 -04:00
parent 5048762c7e
commit dd645ef119
3 changed files with 40 additions and 3 deletions

4
README
View file

@ -20,8 +20,8 @@ The following people made contributions:
Cliff Frey (MP) Cliff Frey (MP)
Xiao Yu (MP) Xiao Yu (MP)
In addition, we are grateful for the patches submitted by Greg Price, In addition, we are grateful for the patches contributed by Greg
Yandong Mao, and Hitoshi Mitake. Price, Yandong Mao, and Hitoshi Mitake.
The code in the files that constitute xv6 is The code in the files that constitute xv6 is
Copyright 2006-2007 Frans Kaashoek, Robert Morris, and Russ Cox. Copyright 2006-2007 Frans Kaashoek, Robert Morris, and Russ Cox.

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@ -324,6 +324,7 @@ mem(void)
void *m1, *m2; void *m1, *m2;
int pid, ppid; int pid, ppid;
printf(1, "mem test\n");
ppid = getpid(); ppid = getpid();
if((pid = fork()) == 0){ if((pid = fork()) == 0){
m1 = 0; m1 = 0;
@ -1332,6 +1333,41 @@ sbrktest(void)
wait(); wait();
} }
// if we run the system out of memory, does it clean up the last
// failed allocation?
sbrk(-(sbrk(0) - oldbrk));
int pids[32];
int fds[2];
if(pipe(fds) != 0){
printf(1, "pipe() failed\n");
exit();
}
for (i = 0; i < sizeof(pids)/sizeof(pids[0]); i++){
if ((pids[i] = fork()) == 0) {
// allocate the full 640K
sbrk((640 * 1024) - (uint)sbrk(0));
write(fds[1], "x", 1);
// sit around until killed
while (1) sleep(1000);
}
char scratch;
if (pids[i] != -1)
read(fds[0], &scratch, 1);
}
// if those failed allocations freed up the pages they did allocate,
// we'll be able to allocate here
c = sbrk(4096);
for (i = 0; i < sizeof(pids)/sizeof(pids[0]); i++){
if (pids[i] == -1)
continue;
kill(pids[i]);
wait();
}
if (c == (char*)0xffffffff) {
printf(stdout, "failed sbrk leaked memory\n");
exit();
}
if(sbrk(0) > oldbrk) if(sbrk(0) > oldbrk)
sbrk(-(sbrk(0) - oldbrk)); sbrk(-(sbrk(0) - oldbrk));

3
vm.c
View file

@ -195,7 +195,8 @@ allocuvm(pde_t *pgdir, char *addr, uint sz)
if(pte == 0 || (*pte & PTE_P) == 0){ if(pte == 0 || (*pte & PTE_P) == 0){
char *mem = kalloc(); char *mem = kalloc();
if(mem == 0){ if(mem == 0){
// XXX clean up? cprintf("allocuvm out of memory\n");
deallocuvm(pgdir, addr, sz);
return 0; return 0;
} }
memset(mem, 0, PGSIZE); memset(mem, 0, PGSIZE);