Re: [PATCH v3 09/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PUD modifying tests

From: Gavin Shan
Date: Thu Jul 22 2021 - 02:47:19 EST

Next message: Shung-Hsi Yu: "BUG: double free of mlx5_cmd_work_ent during shutdown"
Previous message: Shameerali Kolothum Thodi: "RE: [PATCH v2 3/3] kvm/arm: Align the VMID allocation with the arm64 ASID one"
In reply to: Anshuman Khandual: "Re: [PATCH v3 09/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PUD modifying tests"
Next in thread: Gavin Shan: "[PATCH v3 10/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PGD and P4D modifying tests"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hi Anshuman,

On 7/22/21 3:39 PM, Anshuman Khandual wrote:

On 7/19/21 6:36 PM, Gavin Shan wrote:

This uses struct pgtable_debug_args in PUD modifying tests. The allocated
huge page is used when set_pud_at() is used. The corresponding tests
are skipped if the huge page doesn't exist. Besides, the following unused
variables in debug_vm_pgtable() are dropped: @prot, @paddr, @pud_aligned.

Please dont drop @prot, @paddr, @pud_aligned just yet.

Otherwise it will cause build warning ("unused variable") as
explain in previous reply.

Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
mm/debug_vm_pgtable.c | 130 ++++++++++++++++--------------------------
1 file changed, 50 insertions(+), 80 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index cec3cbf99a6b..57b7ead0708b 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -338,55 +338,55 @@ static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
WARN_ON(!pud_bad(pud_mkhuge(pud)));
}
-static void __init pud_advanced_tests(struct mm_struct *mm,
- struct vm_area_struct *vma, pud_t *pudp,
- unsigned long pfn, unsigned long vaddr,
- pgprot_t prot)
+static void __init pud_advanced_tests(struct pgtable_debug_args *args)
{
+ unsigned long vaddr = (args->vaddr & HPAGE_PUD_MASK);
pud_t pud;
if (!has_transparent_hugepage())
return;
pr_debug("Validating PUD advanced\n");
- /* Align the address wrt HPAGE_PUD_SIZE */
- vaddr &= HPAGE_PUD_MASK;

Please just leave these unchanged. If has_transparent_hugepage() evaluates
negative, it skips the masking operation. As mentioned earlier please avoid
changing the test in any manner during these transition patches.

Ok.

+ if (args->pud_pfn == ULONG_MAX) {
+ pr_debug("%s: Skipped\n", __func__);

Just return. Please dont call out "Skipped". Applicable for all transition
patches here.

Ok.

+ return;
+ }
- pud = pfn_pud(pfn, prot);
- set_pud_at(mm, vaddr, pudp, pud);
- pudp_set_wrprotect(mm, vaddr, pudp);
- pud = READ_ONCE(*pudp);
+ pud = pfn_pud(args->pud_pfn, args->page_prot);
+ set_pud_at(args->mm, vaddr, args->pudp, pud);
+ pudp_set_wrprotect(args->mm, vaddr, args->pudp);
+ pud = READ_ONCE(*(args->pudp));

Seems like an extra braces while de-referencing arg->pudp. Could these be
dropped. Just READ_ONCE(*args->pudp).

Ok. Will be dropped in v4.

WARN_ON(pud_write(pud));
#ifndef __PAGETABLE_PMD_FOLDED
- pudp_huge_get_and_clear(mm, vaddr, pudp);
- pud = READ_ONCE(*pudp);
+ pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
- pud = pfn_pud(pfn, prot);
+ pud = pfn_pud(args->pud_pfn, args->page_prot);
pud = pud_wrprotect(pud);
pud = pud_mkclean(pud);
- set_pud_at(mm, vaddr, pudp, pud);
+ set_pud_at(args->mm, vaddr, args->pudp, pud);
pud = pud_mkwrite(pud);
pud = pud_mkdirty(pud);
- pudp_set_access_flags(vma, vaddr, pudp, pud, 1);
- pud = READ_ONCE(*pudp);
+ pudp_set_access_flags(args->vma, vaddr, args->pudp, pud, 1);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(!(pud_write(pud) && pud_dirty(pud)));
#ifndef __PAGETABLE_PMD_FOLDED
- pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1);
- pud = READ_ONCE(*pudp);
+ pudp_huge_get_and_clear_full(args->mm, vaddr, args->pudp, 1);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(!pud_none(pud));
#endif /* __PAGETABLE_PMD_FOLDED */
- pud = pfn_pud(pfn, prot);
+ pud = pfn_pud(args->pud_pfn, args->page_prot);
pud = pud_mkyoung(pud);
- set_pud_at(mm, vaddr, pudp, pud);
- pudp_test_and_clear_young(vma, vaddr, pudp);
- pud = READ_ONCE(*pudp);
+ set_pud_at(args->mm, vaddr, args->pudp, pud);
+ pudp_test_and_clear_young(args->vma, vaddr, args->pudp);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(pud_young(pud));
- pudp_huge_get_and_clear(mm, vaddr, pudp);
+ pudp_huge_get_and_clear(args->mm, vaddr, args->pudp);
}
static void __init pud_leaf_tests(struct pgtable_debug_args *args)
@@ -406,24 +406,14 @@ static void __init pud_leaf_tests(struct pgtable_debug_args *args)
}
#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
-static void __init pud_advanced_tests(struct mm_struct *mm,
- struct vm_area_struct *vma, pud_t *pudp,
- unsigned long pfn, unsigned long vaddr,
- pgprot_t prot)
-{
-}
+static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx) { }
static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx) { }
static void __init pmd_advanced_tests(struct pgtable_debug_args *args) { }
-static void __init pud_advanced_tests(struct mm_struct *mm,
- struct vm_area_struct *vma, pud_t *pudp,
- unsigned long pfn, unsigned long vaddr,
- pgprot_t prot)
-{
-}
+static void __init pud_advanced_tests(struct pgtable_debug_args *args) { }
static void __init pmd_leaf_tests(struct pgtable_debug_args *args) { }
static void __init pud_leaf_tests(struct pgtable_debug_args *args) { }
static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args) { }
@@ -450,11 +440,11 @@ static void __init pmd_huge_tests(struct pgtable_debug_args *args)
WARN_ON(!pmd_none(pmd));
}
-static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
+static void __init pud_huge_tests(struct pgtable_debug_args *args)
{
pud_t pud;
- if (!arch_vmap_pud_supported(prot))
+ if (!arch_vmap_pud_supported(args->page_prot))
return;
pr_debug("Validating PUD huge\n");
@@ -462,15 +452,16 @@ static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot)
* X86 defined pud_set_huge() verifies that the given
* PUD is not a populated non-leaf entry.
*/
- WRITE_ONCE(*pudp, __pud(0));
- WARN_ON(!pud_set_huge(pudp, __pfn_to_phys(pfn), prot));
- WARN_ON(!pud_clear_huge(pudp));
- pud = READ_ONCE(*pudp);
+ WRITE_ONCE(*(args->pudp), __pud(0));
+ WARN_ON(!pud_set_huge(args->pudp, __pfn_to_phys(args->fixed_pud_pfn),
+ args->page_prot));

Please dont break the line, we could go upto 100 width. Please do
the same for the entire series. Improves the readability.

+ WARN_ON(!pud_clear_huge(args->pudp));
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(!pud_none(pud));
}
#else /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
static void __init pmd_huge_tests(struct pgtable_debug_args *args) { }
-static void __init pud_huge_tests(pud_t *pudp, unsigned long pfn, pgprot_t prot) { }
+static void __init pud_huge_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
static void __init p4d_basic_tests(void)
@@ -492,27 +483,26 @@ static void __init pgd_basic_tests(void)
}
#ifndef __PAGETABLE_PUD_FOLDED
-static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp)
+static void __init pud_clear_tests(struct pgtable_debug_args *args)
{
- pud_t pud = READ_ONCE(*pudp);
+ pud_t pud = READ_ONCE(*(args->pudp));
- if (mm_pmd_folded(mm))
+ if (mm_pmd_folded(args->mm))
return;
pr_debug("Validating PUD clear\n");
pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
- WRITE_ONCE(*pudp, pud);
- pud_clear(pudp);
- pud = READ_ONCE(*pudp);
+ WRITE_ONCE(*(args->pudp), pud);
+ pud_clear(args->pudp);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(!pud_none(pud));
}
-static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
- pmd_t *pmdp)
+static void __init pud_populate_tests(struct pgtable_debug_args *args)
{
pud_t pud;
- if (mm_pmd_folded(mm))
+ if (mm_pmd_folded(args->mm))
return;
pr_debug("Validating PUD populate\n");
@@ -520,16 +510,13 @@ static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
* This entry points to next level page table page.
* Hence this must not qualify as pud_bad().
*/
- pud_populate(mm, pudp, pmdp);
- pud = READ_ONCE(*pudp);
+ pud_populate(args->mm, args->pudp, args->start_pmdp);
+ pud = READ_ONCE(*(args->pudp));
WARN_ON(pud_bad(pud));
}
#else /* !__PAGETABLE_PUD_FOLDED */
-static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { }
-static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
- pmd_t *pmdp)
-{
-}
+static void __init pud_clear_tests(struct pgtable_debug_args *args) { }
+static void __init pud_populate_tests(struct pgtable_debug_args *args) { }
#endif /* PAGETABLE_PUD_FOLDED */
#ifndef __PAGETABLE_P4D_FOLDED
@@ -1152,10 +1139,7 @@ static int __init debug_vm_pgtable(void)
pud_t *pudp, *saved_pudp;
pmd_t *pmdp, *saved_pmdp, pmd;
pgtable_t saved_ptep;
- pgprot_t prot;
- phys_addr_t paddr;
unsigned long vaddr;
- unsigned long pud_aligned;
spinlock_t *ptl = NULL;
int idx, ret;
@@ -1164,7 +1148,6 @@ static int __init debug_vm_pgtable(void)
if (ret)
return ret;
- prot = vm_get_page_prot(VMFLAGS);

Please dont drop these just yet and wait until [PATCH 11/12].

vaddr = get_random_vaddr();
mm = mm_alloc();
if (!mm) {
@@ -1178,19 +1161,6 @@ static int __init debug_vm_pgtable(void)
return 1;
}
- /*
- * PFN for mapping at PTE level is determined from a standard kernel
- * text symbol. But pfns for higher page table levels are derived by
- * masking lower bits of this real pfn. These derived pfns might not
- * exist on the platform but that does not really matter as pfn_pxx()
- * helpers will still create appropriate entries for the test. This
- * helps avoid large memory block allocations to be used for mapping
- * at higher page table levels.
- */

Please move this comment as is to the right place inside init_args()
in the first patch itself. If possible all comments should be moved
during the first patch and just the code remains till [PATCH 11/12].

I will include all comments in PATCH[01/12]. In that case, we won't
introduce more changes to unrelated function (init_args()).

- paddr = __pa_symbol(&start_kernel);
-
- pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
-

Please dont drop these just yet and wait until [PATCH 11/12].

Otherwise, it will cause build warning.

pgdp = pgd_offset(mm, vaddr);
p4dp = p4d_alloc(mm, pgdp, vaddr);
pudp = pud_alloc(mm, p4dp, vaddr);
@@ -1282,11 +1252,11 @@ static int __init debug_vm_pgtable(void)
pmd_populate_tests(&args);
spin_unlock(ptl);
- ptl = pud_lock(mm, pudp);
- pud_clear_tests(mm, pudp);
- pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot);
- pud_huge_tests(pudp, pud_aligned, prot);
- pud_populate_tests(mm, pudp, saved_pmdp);
+ ptl = pud_lock(args.mm, args.pudp);
+ pud_clear_tests(&args);
+ pud_advanced_tests(&args);
+ pud_huge_tests(&args);
+ pud_populate_tests(&args);
spin_unlock(ptl);
spin_lock(&mm->page_table_lock);

Thanks,
Gavin

Next message: Shung-Hsi Yu: "BUG: double free of mlx5_cmd_work_ent during shutdown"
Previous message: Shameerali Kolothum Thodi: "RE: [PATCH v2 3/3] kvm/arm: Align the VMID allocation with the arm64 ASID one"
In reply to: Anshuman Khandual: "Re: [PATCH v3 09/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PUD modifying tests"
Next in thread: Gavin Shan: "[PATCH v3 10/12] mm/debug_vm_pgtable: Use struct pgtable_debug_args in PGD and P4D modifying tests"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]