| Message ID | 20210719054138.198373-2-gshan@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/debug_vm_pgtable: Enhancements | expand |
On 7/19/21 3:41 PM, Gavin Shan wrote: > In debug_vm_pgtable(), there are many local variables introduced to > track the needed information and they are passed to the functions for > various test cases. It'd better to introduce a struct as place holder > for these information. With it, what the functions for various test > cases need is the struct, to simplify the code. It also makes code > easier to be maintained. > > Besides, set_xxx_at() could access the data on the corresponding pages > in the page table modifying tests. So the accessed pages in the tests > should have been allocated from buddy. Otherwise, we're accessing pages > that aren't owned by us. This causes issues like page flag corruption. > > This introduces "struct pgtable_debug_args". The struct is initialized > and destroyed, but the information in the struct isn't used yet. They > will be used in subsequent patches. > > Signed-off-by: Gavin Shan <gshan@redhat.com> > --- > mm/debug_vm_pgtable.c | 196 +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 195 insertions(+), 1 deletion(-) > > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index 1c922691aa61..0cc44e7c166e 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -58,6 +58,36 @@ > #define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) > #define RANDOM_NZVALUE GENMASK(7, 0) > > +struct pgtable_debug_args { > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + > + pgd_t *pgdp; > + p4d_t *p4dp; > + pud_t *pudp; > + pmd_t *pmdp; > + pte_t *ptep; > + > + p4d_t *start_p4dp; > + pud_t *start_pudp; > + pmd_t *start_pmdp; > + pgtable_t start_ptep; > + > + unsigned long vaddr; > + pgprot_t page_prot; > + pgprot_t page_prot_none; > + > + unsigned long pud_pfn; > + unsigned long pmd_pfn; > + unsigned long pte_pfn; > + > + unsigned long fixed_pgd_pfn; > + unsigned long fixed_p4d_pfn; > + unsigned long fixed_pud_pfn; > + unsigned long fixed_pmd_pfn; > + unsigned long fixed_pte_pfn; > +}; > + > static void __init pte_basic_tests(unsigned long pfn, int idx) > { > pgprot_t prot = protection_map[idx]; > @@ -955,8 +985,166 @@ static unsigned long __init get_random_vaddr(void) > return random_vaddr; > } > > +static void __init destroy_args(struct pgtable_debug_args *args) > +{ > + struct page *page = NULL; > + > + /* Free (huge) page */ > + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && > + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && > + has_transparent_hugepage() && > + args->pud_pfn != ULONG_MAX) { > + page = pfn_to_page(args->pud_pfn); > + __free_pages(page, HPAGE_PUD_SHIFT - PAGE_SHIFT); > + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && > + has_transparent_hugepage() && > + args->pmd_pfn != ULONG_MAX) { > + page = pfn_to_page(args->pmd_pfn); > + __free_pages(page, HPAGE_PMD_ORDER); > + } else if (args->pte_pfn != ULONG_MAX) { > + page = pfn_to_page(args->pte_pfn); > + __free_pages(page, 0); > + } > + > + /* Free page table */ > + if (args->start_ptep) { > + pte_free(args->mm, args->start_ptep); > + mm_dec_nr_ptes(args->mm); > + } > + > + if (args->start_pmdp) { > + pmd_free(args->mm, args->start_pmdp); > + mm_dec_nr_pmds(args->mm); > + } > + > + if (args->start_pudp) { > + pud_free(args->mm, args->start_pudp); > + mm_dec_nr_puds(args->mm); > + } > + > + if (args->start_p4dp) > + p4d_free(args->mm, args->p4dp); > + > + /* Free vma and mm struct */ > + if (args->vma) > + vm_area_free(args->vma); > + if (args->mm) > + mmdrop(args->mm); > +} > + > +static int __init init_args(struct pgtable_debug_args *args) > +{ > + struct page *page = NULL; > + phys_addr_t phys; > + int ret = 0; > + > + /* Initialize the debugging data */ > + memset(args, 0, sizeof(*args)); > + args->page_prot = vm_get_page_prot(VMFLAGS); > + args->page_prot_none = __P000; > + args->pud_pfn = ULONG_MAX; > + args->pmd_pfn = ULONG_MAX; > + args->pte_pfn = ULONG_MAX; > + args->fixed_pgd_pfn = ULONG_MAX; > + args->fixed_p4d_pfn = ULONG_MAX; > + args->fixed_pud_pfn = ULONG_MAX; > + args->fixed_pmd_pfn = ULONG_MAX; > + args->fixed_pte_pfn = ULONG_MAX; > + > + /* Allocate mm and vma */ > + args->mm = mm_alloc(); > + if (!args->mm) { > + pr_err("Failed to allocate mm struct\n"); > + ret = -ENOMEM; > + goto error; > + } > + > + args->vma = vm_area_alloc(args->mm); > + if (!args->vma) { > + pr_err("Failed to allocate vma\n"); > + ret = -ENOMEM; > + goto error; > + } > + > + /* Figure out the virtual address and allocate page table entries */ > + args->vaddr = get_random_vaddr(); > + args->pgdp = pgd_offset(args->mm, args->vaddr); > + args->p4dp = p4d_alloc(args->mm, args->pgdp, args->vaddr); > + args->pudp = args->p4dp ? > + pud_alloc(args->mm, args->p4dp, args->vaddr) : NULL; > + args->pmdp = args->pudp ? > + pmd_alloc(args->mm, args->pudp, args->vaddr) : NULL; > + args->ptep = args->pmdp ? > + pte_alloc_map(args->mm, args->pmdp, args->vaddr) : NULL; > + if (!args->ptep) { > + pr_err("Failed to allocate page table\n"); > + ret = -ENOMEM; > + goto error; > + } > + > + /* > + * The above page table entries will be modified. Lets save the > + * page table entries so that they can be released when the tests > + * are completed. > + */ > + args->start_p4dp = p4d_offset(args->pgdp, 0UL); > + args->start_pudp = pud_offset(args->p4dp, 0UL); > + args->start_pmdp = pmd_offset(args->pudp, 0UL); > + args->start_ptep = pmd_pgtable(READ_ONCE(*(args->pmdp))); > + > + /* > + * Figure out the fixed addresses, which are all around the kernel > + * symbol (@start_kernel). The corresponding PFNs might be invalid, > + * but it's fine as the following tests won't access the pages. > + */ > + phys = __pa_symbol(&start_kernel); > + args->fixed_pgd_pfn = __phys_to_pfn(phys & PGDIR_MASK); > + args->fixed_p4d_pfn = __phys_to_pfn(phys & P4D_MASK); > + args->fixed_pud_pfn = __phys_to_pfn(phys & PUD_MASK); > + args->fixed_pmd_pfn = __phys_to_pfn(phys & PMD_MASK); > + args->fixed_pte_pfn = __phys_to_pfn(phys & PAGE_MASK); > + > + /* > + * Allocate (huge) pages because some of the tests need to access > + * the data in the pages. The corresponding tests will be skipped > + * if we fail to allocate (huge) pages. > + */ > + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && > + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && > + has_transparent_hugepage()) { > + page = alloc_pages(GFP_KERNEL, HPAGE_PUD_SHIFT - PAGE_SHIFT); > + if (page) { > + args->pud_pfn = page_to_pfn(page); > + args->pmd_pfn = args->pud_pfn; > + args->pte_pfn = args->pud_pfn; > + return 0; > + } > + } > + > + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && > + has_transparent_hugepage()) { > + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); > + if (page) { > + args->pmd_pfn = page_to_pfn(page); > + args->pte_pfn = args->pmd_pfn; > + return 0; > + } > + } > + As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here. So __GFP_NOWARN is needed here. I will fix it in v3 series. > + page = alloc_pages(GFP_KERNEL, 0); > + if (page) > + args->pte_pfn = page_to_pfn(page); > + > + return 0; > + > +error: > + destroy_args(args); > + return ret; > +} > + > static int __init debug_vm_pgtable(void) > { > + struct pgtable_debug_args args; > struct vm_area_struct *vma; > struct mm_struct *mm; > pgd_t *pgdp; > @@ -970,9 +1158,13 @@ static int __init debug_vm_pgtable(void) > unsigned long vaddr, pte_aligned, pmd_aligned; > unsigned long pud_aligned, p4d_aligned, pgd_aligned; > spinlock_t *ptl = NULL; > - int idx; > + int idx, ret; > > pr_info("Validating architecture page table helpers\n"); > + ret = init_args(&args); > + if (ret) > + return ret; > + > prot = vm_get_page_prot(VMFLAGS); > vaddr = get_random_vaddr(); > mm = mm_alloc(); > @@ -1127,6 +1319,8 @@ static int __init debug_vm_pgtable(void) > mm_dec_nr_pmds(mm); > mm_dec_nr_ptes(mm); > mmdrop(mm); > + > + destroy_args(&args); > return 0; > } > late_initcall(debug_vm_pgtable); > Thanks, Gavin
On 7/19/21 6:31 PM, Gavin Shan wrote: >> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && >> + has_transparent_hugepage()) { >> + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); >> + if (page) { >> + args->pmd_pfn = page_to_pfn(page); >> + args->pte_pfn = args->pmd_pfn; >> + return 0; >> + } >> + } >> + > > As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here. > So __GFP_NOWARN is needed here. I will fix it in v3 series. I could find the following build error reported from lkp on V2. mm/debug_vm_pgtable.c:445:8: warning: variable 'pud' set but not used [-Wunused-but-set-variable] Could you please point to the syzbot reported problem on V1 as you have mentioned above. Are there configs where HPAGE_[PMD|PUD]_ORDER is greater than (MAX_ORDER - 1) ? If yes, how adding __GFP_NOWARN solves the problem ?
On 7/20/21 4:42 PM, Anshuman Khandual wrote: > On 7/19/21 6:31 PM, Gavin Shan wrote: >>> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && >>> + has_transparent_hugepage()) { >>> + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); >>> + if (page) { >>> + args->pmd_pfn = page_to_pfn(page); >>> + args->pte_pfn = args->pmd_pfn; >>> + return 0; >>> + } >>> + } >>> + >> >> As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here. >> So __GFP_NOWARN is needed here. I will fix it in v3 series. > > I could find the following build error reported from lkp on V2. > > mm/debug_vm_pgtable.c:445:8: warning: variable 'pud' set but not used [-Wunused-but-set-variable] > Yes, The following line is missed in PATCH[v2 09/12] and fixed in PATCH[v3 09/12]: WARN_ON(!pud_none(pud)). With this line added, the variable @pud is used in v3. > Could you please point to the syzbot reported problem on V1 as you > have mentioned above. Are there configs where HPAGE_[PMD|PUD]_ORDER > is greater than (MAX_ORDER - 1) ? If yes, how adding __GFP_NOWARN > solves the problem ? > https://syzkaller.appspot.com/bug?extid=8730ec44a441a434a2c8 https://syzkaller.appspot.com/x/.config?x=29a82c885e192046 The kernel config has the following options: CONFIG_X86_64=y CONFIG_TRANSPARENT_HUGEPAGE=y CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y #define PUD_SHIFT 30 #define PMD_SHIFT 21 CONFIG_FORCE_MAX_ZONEORDER=n #define MAX_ORDER 11 (HPAGE_PUD_SHIFT - PAGE_SHIFT) >= (1 << MAX_ORDER) (HPAGE_PMD_ORDER) < (1 << MAX_ORDER) The warning is triggered in the following path, __GFP_NOWARN helps to avoid the WARNING_ON_ONCE(), but NULL is returned as expected. alloc_pages __alloc_pages if (unlikely(order >= MAX_ORDER)) { WARN_ON_ONCE(!(gfp & __GFP_NOWARN)); return NULL; } Thanks, Gavin
On 7/21/21 4:59 AM, Gavin Shan wrote: > On 7/20/21 4:42 PM, Anshuman Khandual wrote: >> On 7/19/21 6:31 PM, Gavin Shan wrote: >>>> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && >>>> + has_transparent_hugepage()) { >>>> + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); >>>> + if (page) { >>>> + args->pmd_pfn = page_to_pfn(page); >>>> + args->pte_pfn = args->pmd_pfn; >>>> + return 0; >>>> + } >>>> + } >>>> + >>> >>> As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here. >>> So __GFP_NOWARN is needed here. I will fix it in v3 series. >> >> I could find the following build error reported from lkp on V2. >> >> mm/debug_vm_pgtable.c:445:8: warning: variable 'pud' set but not used [-Wunused-but-set-variable] >> > > Yes, The following line is missed in PATCH[v2 09/12] and fixed in > PATCH[v3 09/12]: WARN_ON(!pud_none(pud)). With this line added, > the variable @pud is used in v3. > >> Could you please point to the syzbot reported problem on V1 as you >> have mentioned above. Are there configs where HPAGE_[PMD|PUD]_ORDER >> is greater than (MAX_ORDER - 1) ? If yes, how adding __GFP_NOWARN >> solves the problem ? >> > > https://syzkaller.appspot.com/bug?extid=8730ec44a441a434a2c8 > https://syzkaller.appspot.com/x/.config?x=29a82c885e192046 > > The kernel config has the following options: > > CONFIG_X86_64=y > CONFIG_TRANSPARENT_HUGEPAGE=y > CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y > #define PUD_SHIFT 30 > #define PMD_SHIFT 21 > > CONFIG_FORCE_MAX_ZONEORDER=n > #define MAX_ORDER 11 > > (HPAGE_PUD_SHIFT - PAGE_SHIFT) >= (1 << MAX_ORDER) > (HPAGE_PMD_ORDER) < (1 << MAX_ORDER) > > The warning is triggered in the following path, __GFP_NOWARN helps to > avoid the WARNING_ON_ONCE(), but NULL is returned as expected. > > alloc_pages > __alloc_pages > > if (unlikely(order >= MAX_ORDER)) { > WARN_ON_ONCE(!(gfp & __GFP_NOWARN)); > return NULL; > } But then that does not allocate the PUD element for the test which subsequently will be skipped. Isn't it ? So if the order is greater than MAX_ORDER, allocation needs to happen via alloc_contig_pages() or something similar.
Hi Anshuman, On 7/21/21 2:50 PM, Anshuman Khandual wrote: > On 7/21/21 4:59 AM, Gavin Shan wrote: >> On 7/20/21 4:42 PM, Anshuman Khandual wrote: >>> On 7/19/21 6:31 PM, Gavin Shan wrote: >>>>> + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && >>>>> + has_transparent_hugepage()) { >>>>> + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); >>>>> + if (page) { >>>>> + args->pmd_pfn = page_to_pfn(page); >>>>> + args->pte_pfn = args->pmd_pfn; >>>>> + return 0; >>>>> + } >>>>> + } >>>>> + >>>> >>>> As syzbot reported against v1 series, we could allocate pages larger than (1 << (MAX_ORDER - 1)) here. >>>> So __GFP_NOWARN is needed here. I will fix it in v3 series. >>> >>> I could find the following build error reported from lkp on V2. >>> >>> mm/debug_vm_pgtable.c:445:8: warning: variable 'pud' set but not used [-Wunused-but-set-variable] >>> >> >> Yes, The following line is missed in PATCH[v2 09/12] and fixed in >> PATCH[v3 09/12]: WARN_ON(!pud_none(pud)). With this line added, >> the variable @pud is used in v3. >> >>> Could you please point to the syzbot reported problem on V1 as you >>> have mentioned above. Are there configs where HPAGE_[PMD|PUD]_ORDER >>> is greater than (MAX_ORDER - 1) ? If yes, how adding __GFP_NOWARN >>> solves the problem ? >>> >> >> https://syzkaller.appspot.com/bug?extid=8730ec44a441a434a2c8 >> https://syzkaller.appspot.com/x/.config?x=29a82c885e192046 >> >> The kernel config has the following options: >> >> CONFIG_X86_64=y >> CONFIG_TRANSPARENT_HUGEPAGE=y >> CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD=y >> #define PUD_SHIFT 30 >> #define PMD_SHIFT 21 >> >> CONFIG_FORCE_MAX_ZONEORDER=n >> #define MAX_ORDER 11 >> >> (HPAGE_PUD_SHIFT - PAGE_SHIFT) >= (1 << MAX_ORDER) >> (HPAGE_PMD_ORDER) < (1 << MAX_ORDER) >> >> The warning is triggered in the following path, __GFP_NOWARN helps to >> avoid the WARNING_ON_ONCE(), but NULL is returned as expected. >> >> alloc_pages >> __alloc_pages >> >> if (unlikely(order >= MAX_ORDER)) { >> WARN_ON_ONCE(!(gfp & __GFP_NOWARN)); >> return NULL; >> } > > But then that does not allocate the PUD element for the test which > subsequently will be skipped. Isn't it ? So if the order is greater > than MAX_ORDER, allocation needs to happen via alloc_contig_pages() > or something similar. > Yes, the corresponding (modifying) tests will be skipped if we fail to allocate the PUD huge page. And we need to use alloc_contig_pages() when CONFIG_CONTIG_ALLOC is enabled. Otherwise, alloc_pages() is still used as best-effort before we fail completely. It's explained to you when we're discussion on PATCH[v3 01/12]. Thanks, Gavin
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 1c922691aa61..0cc44e7c166e 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -58,6 +58,36 @@ #define RANDOM_ORVALUE (GENMASK(BITS_PER_LONG - 1, 0) & ~ARCH_SKIP_MASK) #define RANDOM_NZVALUE GENMASK(7, 0) +struct pgtable_debug_args { + struct mm_struct *mm; + struct vm_area_struct *vma; + + pgd_t *pgdp; + p4d_t *p4dp; + pud_t *pudp; + pmd_t *pmdp; + pte_t *ptep; + + p4d_t *start_p4dp; + pud_t *start_pudp; + pmd_t *start_pmdp; + pgtable_t start_ptep; + + unsigned long vaddr; + pgprot_t page_prot; + pgprot_t page_prot_none; + + unsigned long pud_pfn; + unsigned long pmd_pfn; + unsigned long pte_pfn; + + unsigned long fixed_pgd_pfn; + unsigned long fixed_p4d_pfn; + unsigned long fixed_pud_pfn; + unsigned long fixed_pmd_pfn; + unsigned long fixed_pte_pfn; +}; + static void __init pte_basic_tests(unsigned long pfn, int idx) { pgprot_t prot = protection_map[idx]; @@ -955,8 +985,166 @@ static unsigned long __init get_random_vaddr(void) return random_vaddr; } +static void __init destroy_args(struct pgtable_debug_args *args) +{ + struct page *page = NULL; + + /* Free (huge) page */ + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && + has_transparent_hugepage() && + args->pud_pfn != ULONG_MAX) { + page = pfn_to_page(args->pud_pfn); + __free_pages(page, HPAGE_PUD_SHIFT - PAGE_SHIFT); + } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + has_transparent_hugepage() && + args->pmd_pfn != ULONG_MAX) { + page = pfn_to_page(args->pmd_pfn); + __free_pages(page, HPAGE_PMD_ORDER); + } else if (args->pte_pfn != ULONG_MAX) { + page = pfn_to_page(args->pte_pfn); + __free_pages(page, 0); + } + + /* Free page table */ + if (args->start_ptep) { + pte_free(args->mm, args->start_ptep); + mm_dec_nr_ptes(args->mm); + } + + if (args->start_pmdp) { + pmd_free(args->mm, args->start_pmdp); + mm_dec_nr_pmds(args->mm); + } + + if (args->start_pudp) { + pud_free(args->mm, args->start_pudp); + mm_dec_nr_puds(args->mm); + } + + if (args->start_p4dp) + p4d_free(args->mm, args->p4dp); + + /* Free vma and mm struct */ + if (args->vma) + vm_area_free(args->vma); + if (args->mm) + mmdrop(args->mm); +} + +static int __init init_args(struct pgtable_debug_args *args) +{ + struct page *page = NULL; + phys_addr_t phys; + int ret = 0; + + /* Initialize the debugging data */ + memset(args, 0, sizeof(*args)); + args->page_prot = vm_get_page_prot(VMFLAGS); + args->page_prot_none = __P000; + args->pud_pfn = ULONG_MAX; + args->pmd_pfn = ULONG_MAX; + args->pte_pfn = ULONG_MAX; + args->fixed_pgd_pfn = ULONG_MAX; + args->fixed_p4d_pfn = ULONG_MAX; + args->fixed_pud_pfn = ULONG_MAX; + args->fixed_pmd_pfn = ULONG_MAX; + args->fixed_pte_pfn = ULONG_MAX; + + /* Allocate mm and vma */ + args->mm = mm_alloc(); + if (!args->mm) { + pr_err("Failed to allocate mm struct\n"); + ret = -ENOMEM; + goto error; + } + + args->vma = vm_area_alloc(args->mm); + if (!args->vma) { + pr_err("Failed to allocate vma\n"); + ret = -ENOMEM; + goto error; + } + + /* Figure out the virtual address and allocate page table entries */ + args->vaddr = get_random_vaddr(); + args->pgdp = pgd_offset(args->mm, args->vaddr); + args->p4dp = p4d_alloc(args->mm, args->pgdp, args->vaddr); + args->pudp = args->p4dp ? + pud_alloc(args->mm, args->p4dp, args->vaddr) : NULL; + args->pmdp = args->pudp ? + pmd_alloc(args->mm, args->pudp, args->vaddr) : NULL; + args->ptep = args->pmdp ? + pte_alloc_map(args->mm, args->pmdp, args->vaddr) : NULL; + if (!args->ptep) { + pr_err("Failed to allocate page table\n"); + ret = -ENOMEM; + goto error; + } + + /* + * The above page table entries will be modified. Lets save the + * page table entries so that they can be released when the tests + * are completed. + */ + args->start_p4dp = p4d_offset(args->pgdp, 0UL); + args->start_pudp = pud_offset(args->p4dp, 0UL); + args->start_pmdp = pmd_offset(args->pudp, 0UL); + args->start_ptep = pmd_pgtable(READ_ONCE(*(args->pmdp))); + + /* + * Figure out the fixed addresses, which are all around the kernel + * symbol (@start_kernel). The corresponding PFNs might be invalid, + * but it's fine as the following tests won't access the pages. + */ + phys = __pa_symbol(&start_kernel); + args->fixed_pgd_pfn = __phys_to_pfn(phys & PGDIR_MASK); + args->fixed_p4d_pfn = __phys_to_pfn(phys & P4D_MASK); + args->fixed_pud_pfn = __phys_to_pfn(phys & PUD_MASK); + args->fixed_pmd_pfn = __phys_to_pfn(phys & PMD_MASK); + args->fixed_pte_pfn = __phys_to_pfn(phys & PAGE_MASK); + + /* + * Allocate (huge) pages because some of the tests need to access + * the data in the pages. The corresponding tests will be skipped + * if we fail to allocate (huge) pages. + */ + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) && + has_transparent_hugepage()) { + page = alloc_pages(GFP_KERNEL, HPAGE_PUD_SHIFT - PAGE_SHIFT); + if (page) { + args->pud_pfn = page_to_pfn(page); + args->pmd_pfn = args->pud_pfn; + args->pte_pfn = args->pud_pfn; + return 0; + } + } + + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && + has_transparent_hugepage()) { + page = alloc_pages(GFP_KERNEL, HPAGE_PMD_ORDER); + if (page) { + args->pmd_pfn = page_to_pfn(page); + args->pte_pfn = args->pmd_pfn; + return 0; + } + } + + page = alloc_pages(GFP_KERNEL, 0); + if (page) + args->pte_pfn = page_to_pfn(page); + + return 0; + +error: + destroy_args(args); + return ret; +} + static int __init debug_vm_pgtable(void) { + struct pgtable_debug_args args; struct vm_area_struct *vma; struct mm_struct *mm; pgd_t *pgdp; @@ -970,9 +1158,13 @@ static int __init debug_vm_pgtable(void) unsigned long vaddr, pte_aligned, pmd_aligned; unsigned long pud_aligned, p4d_aligned, pgd_aligned; spinlock_t *ptl = NULL; - int idx; + int idx, ret; pr_info("Validating architecture page table helpers\n"); + ret = init_args(&args); + if (ret) + return ret; + prot = vm_get_page_prot(VMFLAGS); vaddr = get_random_vaddr(); mm = mm_alloc(); @@ -1127,6 +1319,8 @@ static int __init debug_vm_pgtable(void) mm_dec_nr_pmds(mm); mm_dec_nr_ptes(mm); mmdrop(mm); + + destroy_args(&args); return 0; } late_initcall(debug_vm_pgtable);
In debug_vm_pgtable(), there are many local variables introduced to track the needed information and they are passed to the functions for various test cases. It'd better to introduce a struct as place holder for these information. With it, what the functions for various test cases need is the struct, to simplify the code. It also makes code easier to be maintained. Besides, set_xxx_at() could access the data on the corresponding pages in the page table modifying tests. So the accessed pages in the tests should have been allocated from buddy. Otherwise, we're accessing pages that aren't owned by us. This causes issues like page flag corruption. This introduces "struct pgtable_debug_args". The struct is initialized and destroyed, but the information in the struct isn't used yet. They will be used in subsequent patches. Signed-off-by: Gavin Shan <gshan@redhat.com> --- mm/debug_vm_pgtable.c | 196 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 195 insertions(+), 1 deletion(-)