| Message ID | 20230105124528.93813-5-david@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | migration/ram: background snapshot fixes and optimiations | expand |
David Hildenbrand <david@redhat.com> wrote: > ram_mig_ram_block_resized() will abort migration (including background > snapshots) when resizing a RAMBlock. ram_block_populate_read() will only > populate RAM up to used_length, so at least for anonymous memory > protecting everything between used_length and max_length won't > actually be protected and is just a NOP. > > So let's only protect everything up to used_length. > > Note: it still makes sense to register uffd-wp for max_length, such > that RAM_UF_WRITEPROTECT is independent of a changing used_length. > > Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
diff --git a/migration/ram.c b/migration/ram.c index 6a3dbee2c3..73a443f683 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1901,7 +1901,7 @@ int ram_write_tracking_start(void) /* Apply UFFD write protection to the block memory range */ if (uffd_change_protection(rs->uffdio_fd, block->host, - block->max_length, true, false)) { + block->used_length, true, false)) { goto fail; }
ram_mig_ram_block_resized() will abort migration (including background snapshots) when resizing a RAMBlock. ram_block_populate_read() will only populate RAM up to used_length, so at least for anonymous memory protecting everything between used_length and max_length won't actually be protected and is just a NOP. So let's only protect everything up to used_length. Note: it still makes sense to register uffd-wp for max_length, such that RAM_UF_WRITEPROTECT is independent of a changing used_length. Signed-off-by: David Hildenbrand <david@redhat.com> --- migration/ram.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)