From: Dave Hansen dave.hansen@linux.intel.com
mainline inclusion from mainline-v5.1-rc1 commit b926b7f3baecb2a855db629e6822e1a85212e91c category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V CVE: NA
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commit b926b7f3baecb2a855db629e6822e1a85212e91c upstream.
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 dave.hansen@linux.intel.com Reviewed-by: Jerome Glisse jglisse@redhat.com Cc: Dan Williams dan.j.williams@intel.com Cc: Dave Jiang dave.jiang@intel.com Cc: Ross Zwisler zwisler@kernel.org Cc: Vishal Verma vishal.l.verma@intel.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Michal Hocko mhocko@suse.com Cc: linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: Huang Ying ying.huang@intel.com Cc: Fengguang Wu fengguang.wu@intel.com Cc: Keith Busch keith.busch@intel.com Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Fan Du fan.du@intel.com Signed-off-by: Jackie Liu liuyun01@kylinos.cn Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- kernel/resource.c | 9 +++++++++ mm/memory_hotplug.c | 5 ----- 2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/resource.c b/kernel/resource.c index 7dd11c78c738..2cf0edd8223f 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -1126,6 +1126,15 @@ 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; diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 2de62385e336..3f4cf3ab7b51 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -111,11 +111,6 @@ static struct resource *register_memory_resource(u64 start, u64 size) res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY; conflict = request_resource_conflict(&iomem_resource, res); if (conflict) { - if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) { - pr_debug("Device unaddressable memory block " - "memory hotplug at %#010llx !\n", - (unsigned long long)start); - } pr_debug("System RAM resource %pR cannot be added\n", res); kfree(res); return ERR_PTR(-EEXIST);