[v7,2/9] mm, swap: Add infrastructure for saving page metadata on swap

Submitted by Khalid Aziz on Aug. 9, 2017, 9:25 p.m.

Details

Message ID 87ff7a44c45bd6a146102c6e6033ee7810d9ebb5.1502219353.git.khalid.aziz@oracle.com
State Changes Requested
Delegated to: David Miller
Headers show

Commit Message

Khalid Aziz Aug. 9, 2017, 9:25 p.m.
If a processor supports special metadata for a page, for example ADI
version tags on SPARC M7, this metadata must be saved when the page is
swapped out. The same metadata must be restored when the page is swapped
back in. This patch adds two new architecture specific functions -
arch_do_swap_page() to be called when a page is swapped in, and
arch_unmap_one() to be called when a page is being unmapped for swap
out. These architecture hooks allow page metadata to be saved if the
architecture supports it.

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Khalid Aziz <khalid@gonehiking.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
---
v6:
	- Updated parameter list for arch_do_swap_page() and
	  arch_unmap_one()
v5:
	- Replaced set_swp_pte() function with new architecture
	  functions arch_do_swap_page() and arch_unmap_one()

 include/asm-generic/pgtable.h | 36 ++++++++++++++++++++++++++++++++++++
 mm/memory.c                   |  1 +
 mm/rmap.c                     | 13 +++++++++++++
 3 files changed, 50 insertions(+)

Comments

David Miller Aug. 16, 2017, 4:53 a.m.
From: Khalid Aziz <khalid.aziz@oracle.com>
Date: Wed,  9 Aug 2017 15:25:55 -0600

> @@ -1399,6 +1399,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  				(flags & TTU_MIGRATION)) {
>  			swp_entry_t entry;
>  			pte_t swp_pte;
> +
> +			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
> +				set_pte_at(mm, address, pvmw.pte, pteval);
> +				ret = false;
> +				page_vma_mapped_walk_done(&pvmw);
> +				break;
>  			/*
>  			 * Store the pfn of the page in a special migration
>  			 * pte. do_swap_page() will wait until the migration
> @@ -1410,6 +1416,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  			if (pte_soft_dirty(pteval))
>  				swp_pte = pte_swp_mksoft_dirty(swp_pte);
>  			set_pte_at(mm, address, pvmw.pte, swp_pte);
> +			}

This basic block doesn't look right.  I think the new closing brace is
intended to be right after the new break; statement.  If not at the
very least the indentation of the existing code in there needs to be
adjusted.

--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Khalid Aziz Aug. 16, 2017, 2:34 p.m.
On 08/15/2017 10:53 PM, David Miller wrote:
> From: Khalid Aziz <khalid.aziz@oracle.com>
> Date: Wed,  9 Aug 2017 15:25:55 -0600
> 
>> @@ -1399,6 +1399,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>>   				(flags & TTU_MIGRATION)) {
>>   			swp_entry_t entry;
>>   			pte_t swp_pte;
>> +
>> +			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
>> +				set_pte_at(mm, address, pvmw.pte, pteval);
>> +				ret = false;
>> +				page_vma_mapped_walk_done(&pvmw);
>> +				break;
>>   			/*
>>   			 * Store the pfn of the page in a special migration
>>   			 * pte. do_swap_page() will wait until the migration
>> @@ -1410,6 +1416,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>>   			if (pte_soft_dirty(pteval))
>>   				swp_pte = pte_swp_mksoft_dirty(swp_pte);
>>   			set_pte_at(mm, address, pvmw.pte, swp_pte);
>> +			}
> 
> This basic block doesn't look right.  I think the new closing brace is
> intended to be right after the new break; statement.  If not at the
> very least the indentation of the existing code in there needs to be
> adjusted.

Hi Dave,

Thanks. That brace needs to move up right after break. I will fix that.

--
Khalid
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch hide | download patch | download mbox

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 7dfa767dc680..15668c2470b4 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -392,6 +392,42 @@  static inline int pud_same(pud_t pud_a, pud_t pud_b)
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif
 
+#ifndef __HAVE_ARCH_DO_SWAP_PAGE
+/*
+ * Some architectures support metadata associated with a page. When a
+ * page is being swapped out, this metadata must be saved so it can be
+ * restored when the page is swapped back in. SPARC M7 and newer
+ * processors support an ADI (Application Data Integrity) tag for the
+ * page as metadata for the page. arch_do_swap_page() can restore this
+ * metadata when a page is swapped back in.
+ */
+static inline void arch_do_swap_page(struct mm_struct *mm,
+				     struct vm_area_struct *vma,
+				     unsigned long addr,
+				     pte_t pte, pte_t oldpte)
+{
+
+}
+#endif
+
+#ifndef __HAVE_ARCH_UNMAP_ONE
+/*
+ * Some architectures support metadata associated with a page. When a
+ * page is being swapped out, this metadata must be saved so it can be
+ * restored when the page is swapped back in. SPARC M7 and newer
+ * processors support an ADI (Application Data Integrity) tag for the
+ * page as metadata for the page. arch_unmap_one() can save this
+ * metadata on a swap-out of a page.
+ */
+static inline int arch_unmap_one(struct mm_struct *mm,
+				  struct vm_area_struct *vma,
+				  unsigned long addr,
+				  pte_t orig_pte)
+{
+	return 0;
+}
+#endif
+
 #ifndef __HAVE_ARCH_PGD_OFFSET_GATE
 #define pgd_offset_gate(mm, addr)	pgd_offset(mm, addr)
 #endif
diff --git a/mm/memory.c b/mm/memory.c
index bb11c474857e..eb92e4f94d3b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2798,6 +2798,7 @@  int do_swap_page(struct vm_fault *vmf)
 	if (pte_swp_soft_dirty(vmf->orig_pte))
 		pte = pte_mksoft_dirty(pte);
 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
+	arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
 	vmf->orig_pte = pte;
 	if (page == swapcache) {
 		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
diff --git a/mm/rmap.c b/mm/rmap.c
index d405f0e0ee96..5ff2a7943c57 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1399,6 +1399,12 @@  static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				(flags & TTU_MIGRATION)) {
 			swp_entry_t entry;
 			pte_t swp_pte;
+
+			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+				set_pte_at(mm, address, pvmw.pte, pteval);
+				ret = false;
+				page_vma_mapped_walk_done(&pvmw);
+				break;
 			/*
 			 * Store the pfn of the page in a special migration
 			 * pte. do_swap_page() will wait until the migration
@@ -1410,6 +1416,7 @@  static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 			if (pte_soft_dirty(pteval))
 				swp_pte = pte_swp_mksoft_dirty(swp_pte);
 			set_pte_at(mm, address, pvmw.pte, swp_pte);
+			}
 		} else if (PageAnon(page)) {
 			swp_entry_t entry = { .val = page_private(subpage) };
 			pte_t swp_pte;
@@ -1448,6 +1455,12 @@  static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
+			if (arch_unmap_one(mm, vma, address, pteval) < 0) {
+				set_pte_at(mm, address, pvmw.pte, pteval);
+				ret = false;
+				page_vma_mapped_walk_done(&pvmw);
+				break;
+			}
 			if (list_empty(&mm->mmlist)) {
 				spin_lock(&mmlist_lock);
 				if (list_empty(&mm->mmlist))