Re: [PULL 38/47] linux-user: Rename mmap_reserve to mmap_reserve_or_unmap

[Richard Henderson <richard.henderson@linaro.org>]

On 9/18/23 01:35, Andreas Schwab wrote:
> On Jul 15 2023, Richard Henderson wrote:
> 
>> @@ -776,9 +776,15 @@ static void mmap_reserve(abi_ulong start, abi_ulong len)
>>       real_len = real_last - real_start + 1;
>>       host_start = g2h_untagged(real_start);
>>   
>> -    ptr = mmap(host_start, real_len, PROT_NONE,
>> -               MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE | MAP_NORESERVE, -1, 0);
>> -    assert(ptr == host_start);
>> +    if (reserved_va) {
>> +        void *ptr = mmap(host_start, real_len, PROT_NONE,
>> +                         MAP_FIXED | MAP_ANONYMOUS
>> +                         | MAP_PRIVATE | MAP_NORESERVE, -1, 0);
>> +        assert(ptr == host_start);
>> +    } else {
>> +        int ret = munmap(host_start, real_len);
>> +        assert(ret == 0);
> 
> munmap can fail if vm.max_map_count is exceeded.  See the attached test
> (must be run from the current directory):
> 
> $ qemu-riscv64 ./test-free
> qemu-riscv64: ../linux-user/mmap.c:801: mmap_reserve_or_unmap: Assertion `ret == 0' failed.
> **
> ERROR:../accel/tcg/cpu-exec.c:532:cpu_exec_longjmp_cleanup: assertion failed: (cpu == current_cpu)
> Bail out! ERROR:../accel/tcg/cpu-exec.c:532:cpu_exec_longjmp_cleanup: assertion failed: (cpu == current_cpu)
> 

Thanks.  Sent a fix.


r~