Re: [PATCH 1/4] linux-user: fix mremap unmapping adjacent region

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

On 10/11/25 15:03, Matthew Lugg wrote:
> This typo meant that calls to `mremap` which shrink a mapping by some N
> bytes would, when the virtual address space was pre-reserved (e.g.
> 32-bit guest on 64-bit host), unmap the N bytes following the *original*
> mapping.
> 
> Signed-off-by: Matthew Lugg <mlugg@mlugg.co.uk>
> ---
>   linux-user/mmap.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
> index 847092a28a..ec8392b35b 100644
> --- a/linux-user/mmap.c
> +++ b/linux-user/mmap.c
> @@ -1164,7 +1164,8 @@ abi_long target_mremap(abi_ulong old_addr, abi_ulong old_size,
>                       errno = ENOMEM;
>                       host_addr = MAP_FAILED;
>                   } else if (reserved_va && old_size > new_size) {
> -                    mmap_reserve_or_unmap(old_addr + old_size,
> +                    /* Re-reserve pages we just shrunk out of the mapping */
> +                    mmap_reserve_or_unmap(old_addr + new_size,
>                                             old_size - new_size);
>                   }
>               }

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~