On 09/01/2020 12:08 PM, Aneesh Kumar K.V wrote: > On 9/1/20 9:11 AM, Anshuman Khandual wrote: >> >> >> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote: >>> This will help in adding proper locks in a later patch >> >> It really makes sense to classify these tests here as static and dynamic. >> Static are the ones that test via page table entry values modification >> without changing anything on the actual page table itself. Where as the >> dynamic tests do change the page table. Static tests would probably never >> require any lock synchronization but the dynamic ones will do. >> >>> >>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> >>> --- >>> mm/debug_vm_pgtable.c | 52 ++++++++++++++++++++++++------------------- >>> 1 file changed, 29 insertions(+), 23 deletions(-) >>> >>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c >>> index 0ce5c6a24c5b..78c8af3445ac 100644 >>> --- a/mm/debug_vm_pgtable.c >>> +++ b/mm/debug_vm_pgtable.c >>> @@ -992,7 +992,7 @@ static int __init debug_vm_pgtable(void) >>> p4dp = p4d_alloc(mm, pgdp, vaddr); >>> pudp = pud_alloc(mm, p4dp, vaddr); >>> pmdp = pmd_alloc(mm, pudp, vaddr); >>> - ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl); >>> + ptep = pte_alloc_map(mm, pmdp, vaddr); >>> /* >>> * Save all the page table page addresses as the page table >>> @@ -1012,33 +1012,12 @@ static int __init debug_vm_pgtable(void) >>> p4d_basic_tests(p4d_aligned, prot); >>> pgd_basic_tests(pgd_aligned, prot); >>> - pte_clear_tests(mm, ptep, vaddr); >>> - pmd_clear_tests(mm, pmdp); >>> - pud_clear_tests(mm, pudp); >>> - p4d_clear_tests(mm, p4dp); >>> - pgd_clear_tests(mm, pgdp); >>> - >>> - pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> - pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep); >>> - pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot); >>> - hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> - >>> pmd_leaf_tests(pmd_aligned, prot); >>> pud_leaf_tests(pud_aligned, prot); >>> - pmd_huge_tests(pmdp, pmd_aligned, prot); >>> - pud_huge_tests(pudp, pud_aligned, prot); >>> - >>> pte_savedwrite_tests(pte_aligned, protnone); >>> pmd_savedwrite_tests(pmd_aligned, protnone); >>> - pte_unmap_unlock(ptep, ptl); >>> - >>> - pmd_populate_tests(mm, pmdp, saved_ptep); >>> - pud_populate_tests(mm, pudp, saved_pmdp); >>> - p4d_populate_tests(mm, p4dp, saved_pudp); >>> - pgd_populate_tests(mm, pgdp, saved_p4dp); >>> - >>> pte_special_tests(pte_aligned, prot); >>> pte_protnone_tests(pte_aligned, protnone); >>> pmd_protnone_tests(pmd_aligned, protnone); >>> @@ -1056,11 +1035,38 @@ static int __init debug_vm_pgtable(void) >>> pmd_swap_tests(pmd_aligned, prot); >>> swap_migration_tests(); >>> - hugetlb_basic_tests(pte_aligned, prot); >>> pmd_thp_tests(pmd_aligned, prot); >>> pud_thp_tests(pud_aligned, prot); >>> + /* >>> + * Page table modifying tests >>> + */ >> >> In this comment, please do add some more details about how these tests >> need proper locking mechanism unlike the previous static ones. Also add >> a similar comment section for the static tests that dont really change >> page table and need not require corresponding locking mechanism. Both >> comment sections will make this classification clear. >> >>> + pte_clear_tests(mm, ptep, vaddr); >>> + pmd_clear_tests(mm, pmdp); >>> + pud_clear_tests(mm, pudp); >>> + p4d_clear_tests(mm, p4dp); >>> + pgd_clear_tests(mm, pgdp); >>> + >>> + ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl); >>> + pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> + pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep); >>> + pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot); >>> + hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot); >>> + >>> + >>> + pmd_huge_tests(pmdp, pmd_aligned, prot); >>> + pud_huge_tests(pudp, pud_aligned, prot); >>> + >>> + pte_unmap_unlock(ptep, ptl); >>> + >>> + pmd_populate_tests(mm, pmdp, saved_ptep); >>> + pud_populate_tests(mm, pudp, saved_pmdp); >>> + p4d_populate_tests(mm, p4dp, saved_pudp); >>> + pgd_populate_tests(mm, pgdp, saved_p4dp); >>> + >>> + hugetlb_basic_tests(pte_aligned, prot); >> >> hugetlb_basic_tests() is a non page table modifying static test and >> should be classified accordingly. >> >>> + >>> p4d_free(mm, saved_p4dp); >>> pud_free(mm, saved_pudp); >>> pmd_free(mm, saved_pmdp); >>> >> >> Changes till this patch fails to boot on arm64 platform. This should be >> folded with the next patch. >> >> [ 17.080644] ------------[ cut here ]------------ >> [ 17.081342] kernel BUG at mm/pgtable-generic.c:164! >> [ 17.082091] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >> [ 17.082977] Modules linked in: >> [ 17.083481] CPU: 79 PID: 1 Comm: swapper/0 Tainted: G W 5.9.0-rc2-00105-g740e72cd6717 #14 >> [ 17.084998] Hardware name: linux,dummy-virt (DT) >> [ 17.085745] pstate: 60400005 (nZCv daif +PAN -UAO BTYPE=--) >> [ 17.086645] pc : pgtable_trans_huge_deposit+0x58/0x60 >> [ 17.087462] lr : debug_vm_pgtable+0x4dc/0x8f0 >> [ 17.088168] sp : ffff80001219bcf0 >> [ 17.088710] x29: ffff80001219bcf0 x28: ffff8000114ac000 >> [ 17.089574] x27: ffff8000114ac000 x26: 0020000000000fd3 >> [ 17.090431] x25: 0020000081400fd3 x24: fffffe00175c12c0 >> [ 17.091286] x23: ffff0005df04d1a8 x22: 0000f18d6e035000 >> [ 17.092143] x21: ffff0005dd790000 x20: ffff0005df18e1a8 >> [ 17.093003] x19: ffff0005df04cb80 x18: 0000000000000014 >> [ 17.093859] x17: 00000000b76667d0 x16: 00000000fd4e6611 >> [ 17.094716] x15: 0000000000000001 x14: 0000000000000002 >> [ 17.095572] x13: 000000000055d966 x12: fffffe001755e400 >> [ 17.096429] x11: 0000000000000008 x10: ffff0005fcb6e210 >> [ 17.097292] x9 : ffff0005fcb6e210 x8 : 0020000081590fd3 >> [ 17.098149] x7 : ffff0005dd71e0c0 x6 : ffff0005df18e1a8 >> [ 17.099006] x5 : 0020000081590fd3 x4 : 0020000081590fd3 >> [ 17.099862] x3 : ffff0005df18e1a8 x2 : fffffe00175c12c0 >> [ 17.100718] x1 : fffffe00175c1300 x0 : 0000000000000000 >> [ 17.101583] Call trace: >> [ 17.101993] pgtable_trans_huge_deposit+0x58/0x60 >> [ 17.102754] do_one_initcall+0x74/0x1cc >> [ 17.103381] kernel_init_freeable+0x1d0/0x238 >> [ 17.104089] kernel_init+0x14/0x118 >> [ 17.104658] ret_from_fork+0x10/0x34 >> [ 17.105251] Code: f9000443 f9000843 f9000822 d65f03c0 (d4210000) >> [ 17.106303] ---[ end trace e63471e00f8c147f ]--- >> > > IIUC, this should happen even without the series right? This is > > assert_spin_locked(pmd_lockptr(mm, pmdp)); Crash does not happen without this series. A previous patch [PATCH v3 08/13] added pgtable_trans_huge_deposit/withdraw() in pmd_advanced_tests(). arm64 does not define __HAVE_ARCH_PGTABLE_DEPOSIT and hence falls back on generic pgtable_trans_huge_deposit() which the asserts the lock.
