On 04.09.24 19:57, Yang Shi wrote:
On 9/3/24 2:35 PM, David Hildenbrand wrote:
On 03.09.24 18:46, Yang Shi wrote:
On 9/2/24 7:33 AM, David Hildenbrand wrote:
On 21.08.24 20:47, Yang Shi wrote:
Enable MTE support for hugetlb.
The MTE page flags will be set on the head page only. When copying
hugetlb folio, the tags for all tail pages will be copied when copying
head page.
When freeing hugetlb folio, the MTE flags will be cleared.
Signed-off-by: Yang Shi <yang@xxxxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/hugetlb.h | 11 ++++++++++-
arch/arm64/include/asm/mman.h | 3 ++-
arch/arm64/kernel/hibernate.c | 7 +++++++
arch/arm64/kernel/mte.c | 25 +++++++++++++++++++++++--
arch/arm64/kvm/guest.c | 16 +++++++++++++---
arch/arm64/kvm/mmu.c | 11 +++++++++++
arch/arm64/mm/copypage.c | 25 +++++++++++++++++++++++--
fs/hugetlbfs/inode.c | 2 +-
8 files changed, 90 insertions(+), 10 deletions(-)
v2: * Reimplemented the patch to fix the comments from Catalin.
* Added test cases (patch #2) per Catalin.
diff --git a/arch/arm64/include/asm/hugetlb.h
b/arch/arm64/include/asm/hugetlb.h
index 293f880865e8..00a1f75d40ee 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -11,6 +11,7 @@
#define __ASM_HUGETLB_H
#include <asm/cacheflush.h>
+#include <asm/mte.h>
#include <asm/page.h>
#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
@@ -20,7 +21,15 @@ extern bool
arch_hugetlb_migration_supported(struct hstate *h);
static inline void arch_clear_hugetlb_flags(struct folio *folio)
{
- clear_bit(PG_dcache_clean, &folio->flags);
+ const unsigned long clear_flags = BIT(PG_dcache_clean) |
+ BIT(PG_mte_tagged) | BIT(PG_mte_lock);
+
+ if (!system_supports_mte()) {
+ clear_bit(PG_dcache_clean, &folio->flags);
+ return;
+ }
+
+ folio->flags &= ~clear_flags;
}
#define arch_clear_hugetlb_flags arch_clear_hugetlb_flags
diff --git a/arch/arm64/include/asm/mman.h
b/arch/arm64/include/asm/mman.h
index 5966ee4a6154..304dfc499e68 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h
@@ -28,7 +28,8 @@ static inline unsigned long
arch_calc_vm_flag_bits(unsigned long flags)
* backed by tags-capable memory. The vm_flags may be
overridden by a
* filesystem supporting MTE (RAM-based).
*/
- if (system_supports_mte() && (flags & MAP_ANONYMOUS))
+ if (system_supports_mte() &&
+ (flags & (MAP_ANONYMOUS | MAP_HUGETLB)))
return VM_MTE_ALLOWED;
return 0;
diff --git a/arch/arm64/kernel/hibernate.c
b/arch/arm64/kernel/hibernate.c
index 02870beb271e..722e76f29141 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -266,10 +266,17 @@ static int swsusp_mte_save_tags(void)
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn;
pfn++) {
struct page *page = pfn_to_online_page(pfn);
+ struct folio *folio;
if (!page)
continue;
+ folio = page_folio(page);
+
+ if (folio_test_hugetlb(folio) &&
+ !page_mte_tagged(&folio->page))
+ continue;
Can we have folio_test_mte_tagged() whereby you make sure that only
folio_test_hugetlb() uses it for now (VM_WARN_ON_ONCE) and then make
sure that nobody uses page_mte_tagged() on hugetlb folios
(VM_WARN_ON_ONCE)?
IIUC, you mean something like the below?
bool folio_test_mte_tagged(struct folio *folio)
{
VM_WARN_ON_ONCE(!folio_test_hugetlb(folio));
return test_bit(PG_mte_tagged, &folio->page->flags);
folio->flags
}
bool page_mte_tagged(struct page *page)
{
struct folio *folio = page_folio(page);
VM_WARN_ON_ONCE(folio_test_hugetlb(folio));
Yes, but better as
VM_WARN_ON_ONCE(folio_test_hugetlb(page_folio(page)));
I see. But I think all the call sites for folio_test_mte_tagged()
actually need have folio_test_hugetlb() before it. So the warn seems not
very useful other than warning on some misuse.
... well, that's the whole reason for them :)
return test_bit(PG_mte_tagged, &pge->flags);
}
Same for folio_set_mte_tagged() and other functions. We could slap a
"hugetlb" into the function names, but maybe in the future we'll be
able to use a single flag per folio (I know, it's complicated ...).
A single flag per folio should be the future direction, but I haven't
done the research so can't tell how complicated it will be.
There were some discussions on it, and it's tricky. So maybe we should
really just have folio_test_hugetlb_mte_tagged() etc. for now
Either w/ hugetlb or w/o hugetlb is fine, I don't have strong opinion on
the naming.
Let's go with "hugetlb" for now, using it for other large folios is out
of sight a bit ... at least right now :)
--
Cheers,
David / dhildenb
