From b926b7f3baecb2a855db629e6822e1a85212e91c Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Mon, 25 Feb 2019 10:57:33 -0800 Subject: mm/resource: Move HMM pr_debug() deeper into resource code HMM consumes physical address space for its own use, even though nothing is mapped or accessible there. It uses a special resource description (IORES_DESC_DEVICE_PRIVATE_MEMORY) to uniquely identify these areas. When HMM consumes address space, it makes a best guess about what to consume. However, it is possible that a future memory or device hotplug can collide with the reserved area. In the case of these conflicts, there is an error message in register_memory_resource(). Later patches in this series move register_memory_resource() from using request_resource_conflict() to __request_region(). Unfortunately, __request_region() does not return the conflict like the previous function did, which makes it impossible to check for IORES_DESC_DEVICE_PRIVATE_MEMORY in a conflicting resource. Instead of warning in register_memory_resource(), move the check into the core resource code itself (__request_region()) where the conflicting resource _is_ available. This has the added bonus of producing a warning in case of HMM conflicts with devices *or* RAM address space, as opposed to the RAM- only warnings that were there previously. Signed-off-by: Dave Hansen Reviewed-by: Jerome Glisse Cc: Dan Williams Cc: Dave Jiang Cc: Ross Zwisler Cc: Vishal Verma Cc: Tom Lendacky Cc: Andrew Morton Cc: Michal Hocko Cc: linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: Huang Ying Cc: Fengguang Wu Cc: Keith Busch Signed-off-by: Dan Williams --- kernel/resource.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'kernel/resource.c') diff --git a/kernel/resource.c b/kernel/resource.c index ca7ed5158cff..35fe105d581e 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -1132,6 +1132,15 @@ struct resource * __request_region(struct resource *parent, conflict = __request_resource(parent, res); if (!conflict) break; + /* + * mm/hmm.c reserves physical addresses which then + * become unavailable to other users. Conflicts are + * not expected. Warn to aid debugging if encountered. + */ + if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) { + pr_warn("Unaddressable device %s %pR conflicts with %pR", + conflict->name, conflict, res); + } if (conflict != parent) { if (!(conflict->flags & IORESOURCE_BUSY)) { parent = conflict; -- cgit v1.2.3-70-g09d2