mm/resource: Let walk_system_ram_range() search child resources

hansendc · djbw · commit 2b539aefe9e4 · 2019-02-28T10:41:23.000-08:00
In the process of onlining memory, we use walk_system_ram_range()
to find the actual RAM areas inside of the area being onlined.

However, it currently only finds memory resources which are
"top-level" iomem_resources.  Children are not currently
searched which causes it to skip System RAM in areas like this
(in the format of /proc/iomem):

a0000000-bfffffff : Persistent Memory (legacy)
  a0000000-afffffff : System RAM

Changing the true-&gt;false here allows children to be searched
as well.  We need this because we add a new "System RAM"
resource underneath the "persistent memory" resource when
we use persistent memory in a volatile mode.

Signed-off-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: Keith Busch &lt;keith.busch@intel.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Dave Jiang &lt;dave.jiang@intel.com&gt;
Cc: Ross Zwisler &lt;zwisler@kernel.org&gt;
Cc: Vishal Verma &lt;vishal.l.verma@intel.com&gt;
Cc: Tom Lendacky &lt;thomas.lendacky@amd.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: linux-nvdimm@lists.01.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: Huang Ying &lt;ying.huang@intel.com&gt;
Cc: Fengguang Wu &lt;fengguang.wu@intel.com&gt;
Cc: Borislav Petkov &lt;bp@suse.de&gt;
Cc: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
Cc: Yaowei Bai &lt;baiyaowei@cmss.chinamobile.com&gt;
Cc: Takashi Iwai &lt;tiwai@suse.de&gt;
Cc: Jerome Glisse &lt;jglisse@redhat.com&gt;
Signed-off-by: Dan Williams &lt;dan.j.williams@intel.com&gt;
diff --git a/kernel/resource.c b/kernel/resource.c
@@ -454,6 +454,9 @@ int walk_mem_res(u64 start, u64 end, void *arg,
  * This function calls the @func callback against all memory ranges of type
  * System RAM which are marked as IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY.
  * It is to be used only for System RAM.
+ *
+ * This will find System RAM ranges that are children of top-level resources
+ * in addition to top-level System RAM resources.
  */
 int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 			  void *arg, int (*func)(unsigned long, unsigned long, void *))
@@ -469,7 +472,7 @@ int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
 	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 	while (start < end &&
 	       !find_next_iomem_res(start, end, flags, IORES_DESC_NONE,
-				    true, &res)) {
+				    false, &res)) {
 		pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		end_pfn = (res.end + 1) >> PAGE_SHIFT;
 		if (end_pfn > pfn)
