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

[Matthew Lugg <mlugg@mlugg.co.uk>]

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);
                 }
             }
-- 
2.51.0