| Message ID | 20230105124528.93813-3-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | migration/ram: background snapshot fixes and optimiations | expand |
David Hildenbrand <david@redhat.com> wrote: > If something goes wrong during uffd_change_protection(), we would miss > to unregister uffd-wp and not release our reference. Fix it by > performing the uffd_change_protection(true) last. > > Note that a uffd_change_protection(false) on the recovery path without a > prior uffd_change_protection(false) is fine. > > Fixes: 278e2f551a09 ("migration: support UFFD write fault processing in ram_save_iterate()") > Cc: qemu-stable@nongnu.org > 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 b8f58d2a40..6e4e41952a 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1896,13 +1896,14 @@ int ram_write_tracking_start(void) block->max_length, UFFDIO_REGISTER_MODE_WP, NULL)) { goto fail; } + block->flags |= RAM_UF_WRITEPROTECT; + memory_region_ref(block->mr); + /* Apply UFFD write protection to the block memory range */ if (uffd_change_protection(rs->uffdio_fd, block->host, block->max_length, true, false)) { goto fail; } - block->flags |= RAM_UF_WRITEPROTECT; - memory_region_ref(block->mr); trace_ram_write_tracking_ramblock_start(block->idstr, block->page_size, block->host, block->max_length);
If something goes wrong during uffd_change_protection(), we would miss to unregister uffd-wp and not release our reference. Fix it by performing the uffd_change_protection(true) last. Note that a uffd_change_protection(false) on the recovery path without a prior uffd_change_protection(false) is fine. Fixes: 278e2f551a09 ("migration: support UFFD write fault processing in ram_save_iterate()") Cc: qemu-stable@nongnu.org Signed-off-by: David Hildenbrand <david@redhat.com> --- migration/ram.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)