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Date: Wed, 19 May 2021 09:43:08 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: linux-mm@...ck.org, akpm@...ux-foundation.org
Cc: Anshuman Khandual <anshuman.khandual@....com>,
"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org
Subject: [PATCH V2] mm/debug_vm_pgtable: Ensure THP availability via has_transparent_hugepage()
On certain platforms, THP support could not just be validated via the build
option CONFIG_TRANSPARENT_HUGEPAGE. Instead has_transparent_hugepage() also
needs to be called upon to verify THP runtime support. Otherwise the debug
test will just run into unusable THP helpers like in the case of a 4K hash
config on powerpc platform [1]. This just moves all pfn_pmd() and pfn_pud()
after THP runtime validation with has_transparent_hugepage() which prevents
the mentioned problem.
[1] https://bugzilla.kernel.org/show_bug.cgi?id=213069
Cc: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Fixes: 787d563b8642 ("mm/debug_vm_pgtable: fix kernel crash by checking for THP support")
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
This applies on v5.13-rc2.
Changes in V2:
- Updated [pmd|pud]_advanced_tests() per Christophe
- Added "Fixes: " tag per Christophe
Changes in V1:
https://lore.kernel.org/linux-mm/1621325590-18199-1-git-send-email-anshuman.khandual@arm.com/
mm/debug_vm_pgtable.c | 63 ++++++++++++++++++++++++++++++++++---------
1 file changed, 51 insertions(+), 12 deletions(-)
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 05efe98a9ac2..b3c7e7b04cb9 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -146,13 +146,14 @@ static void __init pte_savedwrite_tests(unsigned long pfn, pgprot_t prot)
static void __init pmd_basic_tests(unsigned long pfn, int idx)
{
pgprot_t prot = protection_map[idx];
- pmd_t pmd = pfn_pmd(pfn, prot);
unsigned long val = idx, *ptr = &val;
+ pmd_t pmd;
if (!has_transparent_hugepage())
return;
pr_debug("Validating PMD basic (%pGv)\n", ptr);
+ pmd = pfn_pmd(pfn, prot);
/*
* This test needs to be executed after the given page table entry
@@ -185,7 +186,7 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
unsigned long pfn, unsigned long vaddr,
pgprot_t prot, pgtable_t pgtable)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
if (!has_transparent_hugepage())
return;
@@ -232,9 +233,14 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
+
+ if (!has_transparent_hugepage())
+ return;
pr_debug("Validating PMD leaf\n");
+ pmd = pfn_pmd(pfn, prot);
+
/*
* PMD based THP is a leaf entry.
*/
@@ -267,12 +273,16 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
return;
+ if (!has_transparent_hugepage())
+ return;
+
pr_debug("Validating PMD saved write\n");
+ pmd = pfn_pmd(pfn, prot);
WARN_ON(!pmd_savedwrite(pmd_mk_savedwrite(pmd_clear_savedwrite(pmd))));
WARN_ON(pmd_savedwrite(pmd_clear_savedwrite(pmd_mk_savedwrite(pmd))));
}
@@ -281,13 +291,14 @@ static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot)
static void __init pud_basic_tests(struct mm_struct *mm, unsigned long pfn, int idx)
{
pgprot_t prot = protection_map[idx];
- pud_t pud = pfn_pud(pfn, prot);
unsigned long val = idx, *ptr = &val;
+ pud_t pud;
if (!has_transparent_hugepage())
return;
pr_debug("Validating PUD basic (%pGv)\n", ptr);
+ pud = pfn_pud(pfn, prot);
/*
* This test needs to be executed after the given page table entry
@@ -323,7 +334,7 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
unsigned long pfn, unsigned long vaddr,
pgprot_t prot)
{
- pud_t pud = pfn_pud(pfn, prot);
+ pud_t pud;
if (!has_transparent_hugepage())
return;
@@ -332,6 +343,7 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
/* Align the address wrt HPAGE_PUD_SIZE */
vaddr = (vaddr & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE;
+ pud = pfn_pud(pfn, prot);
set_pud_at(mm, vaddr, pudp, pud);
pudp_set_wrprotect(mm, vaddr, pudp);
pud = READ_ONCE(*pudp);
@@ -370,9 +382,13 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
static void __init pud_leaf_tests(unsigned long pfn, pgprot_t prot)
{
- pud_t pud = pfn_pud(pfn, prot);
+ pud_t pud;
+
+ if (!has_transparent_hugepage())
+ return;
pr_debug("Validating PUD leaf\n");
+ pud = pfn_pud(pfn, prot);
/*
* PUD based THP is a leaf entry.
*/
@@ -654,12 +670,16 @@ static void __init pte_protnone_tests(unsigned long pfn, pgprot_t prot)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+ pmd_t pmd;
if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
return;
+ if (!has_transparent_hugepage())
+ return;
+
pr_debug("Validating PMD protnone\n");
+ pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
WARN_ON(!pmd_protnone(pmd));
WARN_ON(!pmd_present(pmd));
}
@@ -679,18 +699,26 @@ static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
+
+ if (!has_transparent_hugepage())
+ return;
pr_debug("Validating PMD devmap\n");
+ pmd = pfn_pmd(pfn, prot);
WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd)));
}
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot)
{
- pud_t pud = pfn_pud(pfn, prot);
+ pud_t pud;
+
+ if (!has_transparent_hugepage())
+ return;
pr_debug("Validating PUD devmap\n");
+ pud = pfn_pud(pfn, prot);
WARN_ON(!pud_devmap(pud_mkdevmap(pud)));
}
#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
@@ -733,25 +761,33 @@ static void __init pte_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
return;
+ if (!has_transparent_hugepage())
+ return;
+
pr_debug("Validating PMD soft dirty\n");
+ pmd = pfn_pmd(pfn, prot);
WARN_ON(!pmd_soft_dirty(pmd_mksoft_dirty(pmd)));
WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd)));
}
static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
{
- pmd_t pmd = pfn_pmd(pfn, prot);
+ pmd_t pmd;
if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) ||
!IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
return;
+ if (!has_transparent_hugepage())
+ return;
+
pr_debug("Validating PMD swap soft dirty\n");
+ pmd = pfn_pmd(pfn, prot);
WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
}
@@ -780,6 +816,9 @@ static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot)
swp_entry_t swp;
pmd_t pmd;
+ if (!has_transparent_hugepage())
+ return;
+
pr_debug("Validating PMD swap\n");
pmd = pfn_pmd(pfn, prot);
swp = __pmd_to_swp_entry(pmd);
--
2.20.1
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