mm: fix cache mode of dax pmd mappings
track_pfn_insert() in vmf_insert_pfn_pmd() is marking dax mappings as
uncacheable rendering them impractical for application usage. DAX-pte
mappings are cached and the goal of establishing DAX-pmd mappings is to
attain more performance, not dramatically less (3 orders of magnitude).
track_pfn_insert() relies on a previous call to reserve_memtype() to
establish the expected page_cache_mode for the range. While memremap()
arranges for reserve_memtype() to be called, devm_memremap_pages() does
not. So, teach track_pfn_insert() and untrack_pfn() how to handle
tracking without a vma, and arrange for devm_memremap_pages() to
establish the write-back-cache reservation in the memtype tree.
Cc: <stable@vger.kernel.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Nilesh Choudhury <nilesh.choudhury@oracle.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Reported-by: Kai Zhang <kai.ka.zhang@oracle.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 251d16b..b501e39 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -247,6 +247,7 @@
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(resource_size(res), SECTION_SIZE);
arch_remove_memory(align_start, align_size);
+ untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
pgmap_radix_release(res);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
"%s: failed to free all reserved pages\n", __func__);
@@ -282,6 +283,7 @@
struct percpu_ref *ref, struct vmem_altmap *altmap)
{
resource_size_t key, align_start, align_size, align_end;
+ pgprot_t pgprot = PAGE_KERNEL;
struct dev_pagemap *pgmap;
struct page_map *page_map;
int error, nid, is_ram;
@@ -351,6 +353,11 @@
if (nid < 0)
nid = numa_mem_id();
+ error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0,
+ align_size);
+ if (error)
+ goto err_pfn_remap;
+
error = arch_add_memory(nid, align_start, align_size, true);
if (error)
goto err_add_memory;
@@ -371,6 +378,8 @@
return __va(res->start);
err_add_memory:
+ untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
+ err_pfn_remap:
err_radix:
pgmap_radix_release(res);
devres_free(page_map);