diff options
| -rw-r--r-- | softmmu/physmem.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/softmmu/physmem.c b/softmmu/physmem.c index bda475a719..3df73542e1 100644 --- a/softmmu/physmem.c +++ b/softmmu/physmem.c @@ -3456,6 +3456,24 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) * so a userfault will trigger. */ #ifdef CONFIG_FALLOCATE_PUNCH_HOLE + /* + * We'll discard data from the actual file, even though we only + * have a MAP_PRIVATE mapping, possibly messing with other + * MAP_PRIVATE/MAP_SHARED mappings. There is no easy way to + * change that behavior whithout violating the promised + * semantics of ram_block_discard_range(). + * + * Only warn, because it works as long as nobody else uses that + * file. + */ + if (!qemu_ram_is_shared(rb)) { + warn_report_once("ram_block_discard_range: Discarding RAM" + " in private file mappings is possibly" + " dangerous, because it will modify the" + " underlying file and will affect other" + " users of the file"); + } + ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, start, length); if (ret) { |