From e54223275ba1bc6f704a6bab015fcd2ae4f72572 Mon Sep 17 00:00:00 2001 From: Ross Lagerwall Date: Thu, 25 May 2023 16:32:48 +0100 Subject: [PATCH] PCI: Release resource invalidated by coalescing 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 Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org # v5.16+ --- drivers/pci/probe.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 0b2826c..00ed20a 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -997,8 +997,10 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) 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); -- 2.7.4