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@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Cc: Nilesh Choudhury <nilesh.choudhury@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Toshi Kani <toshi.kani@xxxxxxx>
Reported-by: Kai Zhang <kai.ka.zhang@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
arch/x86/mm/pat.c | 17 ++++++++++-------
kernel/memremap.c | 9 +++++++++
2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index ecb1b69c1651..170cc4ff057b 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -927,9 +927,10 @@ int track_pfn_copy(struct vm_area_struct *vma)
}
/*
- * prot is passed in as a parameter for the new mapping. If the vma has a
- * linear pfn mapping for the entire range reserve the entire vma range with
- * single reserve_pfn_range call.
+ * prot is passed in as a parameter for the new mapping. If the vma has
+ * a linear pfn mapping for the entire range, or no vma is provided,
+ * reserve the entire pfn + size range with single reserve_pfn_range
+ * call.
*/
int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
unsigned long pfn, unsigned long addr, unsigned long size)
@@ -938,11 +939,12 @@ int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
enum page_cache_mode pcm;
/* reserve the whole chunk starting from paddr */
- if (addr == vma->vm_start && size == (vma->vm_end - vma->vm_start)) {
+ if (!vma || (addr == vma->vm_start
+ && size == (vma->vm_end - vma->vm_start))) {
int ret;
ret = reserve_pfn_range(paddr, size, prot, 0);
- if (!ret)
+ if (ret == 0 && vma)
vma->vm_flags |= VM_PAT;
return ret;
}
@@ -997,7 +999,7 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
resource_size_t paddr;
unsigned long prot;
- if (!(vma->vm_flags & VM_PAT))
+ if (vma && !(vma->vm_flags & VM_PAT))
return;
/* free the chunk starting from pfn or the whole chunk */
@@ -1011,7 +1013,8 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
size = vma->vm_end - vma->vm_start;
}
free_pfn_range(paddr, size);
- vma->vm_flags &= ~VM_PAT;
+ if (vma)
+ vma->vm_flags &= ~VM_PAT;
}
/*
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 251d16b4cb41..b501e390bb34 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -247,6 +247,7 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
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 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
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 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
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 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
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);
--
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