From: Ross Lagerwall ross.lagerwall@citrix.com
commit e54223275ba1bc6f704a6bab015fcd2ae4f72572 upstream.
When contiguous windows are coalesced by pci_register_host_bridge(), the second resource is expanded to include the first, and the first is invalidated and consequently not added to the bus. However, it remains in the resource hierarchy. For example, these windows:
fec00000-fec7ffff : PCI Bus 0000:00 fec80000-fecbffff : PCI Bus 0000:00
are coalesced into this, where the first resource remains in the tree with start/end zeroed out:
00000000-00000000 : PCI Bus 0000:00 fec00000-fecbffff : PCI Bus 0000:00
In some cases (e.g. the Xen scratch region), this causes future calls to allocate_resource() to choose an inappropriate location which the caller cannot handle.
Fix by releasing the zeroed-out resource and removing it from the resource hierarchy.
[bhelgaas: commit log] Fixes: 7c3855c423b1 ("PCI: Coalesce host bridge contiguous apertures") Link: https://lore.kernel.org/r/20230525153248.712779-1-ross.lagerwall@citrix.com Signed-off-by: Ross Lagerwall ross.lagerwall@citrix.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Cc: stable@vger.kernel.org # v5.16+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/probe.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -994,8 +994,10 @@ static int pci_register_host_bridge(stru resource_list_for_each_entry_safe(window, n, &resources) { offset = window->offset; res = window->res; - if (!res->flags && !res->start && !res->end) + if (!res->flags && !res->start && !res->end) { + release_resource(res); continue; + }
list_move_tail(&window->node, &bridge->windows);