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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id x19sm13105844qtm.47.2020.03.03.17.39.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 03 Mar 2020 17:39:42 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3608.60.0.2.5\)) Subject: Re: [PATCH V14] mm/debug: Add tests validating architecture page table helpers From: Qian Cai In-Reply-To: Date: Tue, 3 Mar 2020 20:39:39 -0500 Cc: Christophe Leroy , Linux Memory Management List , Andrew Morton , Mike Rapoport , Vineet Gupta , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "Kirill A . Shutemov" , Paul Walmsley , Palmer Dabbelt , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev , linux-s390@vger.kernel.org, linux-riscv@lists.infradead.org, the arch/x86 maintainers , linux-arch@vger.kernel.org, LKML , "Aneesh Kumar K.V" Content-Transfer-Encoding: quoted-printable Message-Id: <12260F9A-695D-40F8-932F-61D86D77D441@lca.pw> References: <1581909460-19148-1-git-send-email-anshuman.khandual@arm.com> <1582726182.7365.123.camel@lca.pw> <7c707b7f-ce3d-993b-8042-44fdc1ed28bf@c-s.fr> <1582732318.7365.129.camel@lca.pw> <1583178042.7365.146.camel@lca.pw> To: Anshuman Khandual X-Mailer: Apple Mail (2.3608.60.0.2.5) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > Below is slightly modified version of your change above and should = still > prevent the bug on powerpc. Will it be possible for you to re-test = this > ? Once confirmed, will send a patch enabling this test on powerpc64 > keeping your authorship. Thank you. This works fine on radix MMU but I decided to go a bit future to test = hash MMU. The kernel will stuck here below. I did confirm that = pte_alloc_map_lock() was successful, so I don=E2=80=99t understand hash MMU well enough to = tell why it could still take an interrupt at pte_clear_tests() even before we = calls pte_unmap_unlock()? [ 33.881515][ T1] ok 8 - property-entry [ 33.883653][ T1] debug_vm_pgtable: debug_vm_pgtable: Validating architecture page table helpers [ 60.418885][ C8] watchdog: BUG: soft lockup - CPU#8 stuck for 23s! [swapper/0:1] [ 60.418913][ C8] Modules linked in: [ 60.418927][ C8] irq event stamp: 2896762 [ 60.418945][ C8] hardirqs last enabled at (2896761): = [] fast_exc_return_irq+0x28/0x34 [ 60.418960][ C8] hardirqs last disabled at (2896762): = [] decrementer_common+0x10c/0x130 [ 60.418985][ C8] softirqs last enabled at (2896760): = [] __do_softirq+0x640/0x8c8 [ 60.419009][ C8] softirqs last disabled at (2896753): = [] irq_exit+0x16c/0x1d0 [ 60.419024][ C8] CPU: 8 PID: 1 Comm: swapper/0 Not tainted = 5.6.0-rc4-next- 20200303+ #7 [ 60.419055][ C8] NIP: c00000000103dc14 LR: c00000000103db0c CTR: 0000000000000000 [ 60.419076][ C8] REGS: c00000003dd4fa30 TRAP: 0901 Not tainted = (5.6.0- rc4-next-20200303+) [ 60.419107][ C8] MSR: 9000000000009033 = CR: 42000222 XER: 00000000 [ 60.419134][ C8] CFAR: c00000000103dc1c IRQMASK: 0=20 [ 60.419134][ C8] GPR00: c00000000103db0c c00000003dd4fcc0 = c000000001657d00 05210001000000c0=20 [ 60.419134][ C8] GPR04: 8000000000000105 000000000000000a = 00000000f4d9864c 0000000000000001=20 [ 60.419134][ C8] GPR08: 0000000000000000 ffffffffffffffff = 0000000000000001 00000000000a0000=20 [ 60.419134][ C8] GPR12: 0000000000000000 c000001fffff9880=20 [ 60.419220][ C8] NIP [c00000000103dc14] = debug_vm_pgtable+0x7a8/0xbb4 hash__pte_update at arch/powerpc/include/asm/book3s/64/hash.h:159 (inlined by) pte_update at = arch/powerpc/include/asm/book3s/64/pgtable.h:359 (inlined by) pte_clear at = arch/powerpc/include/asm/book3s/64/pgtable.h:477 (inlined by) pte_clear_tests at mm/debug_vm_pgtable.c:259 (inlined by) debug_vm_pgtable at mm/debug_vm_pgtable.c:368 [ 60.419241][ C8] LR [c00000000103db0c] = debug_vm_pgtable+0x6a0/0xbb4 pmd_basic_tests at mm/debug_vm_pgtable.c:74 (inlined by) debug_vm_pgtable at mm/debug_vm_pgtable.c:363 [ 60.419260][ C8] Call Trace: [ 60.419278][ C8] [c00000003dd4fcc0] [c00000000103d994] debug_vm_pgtable+0x528/0xbb4 (unreliable) [ 60.419302][ C8] [c00000003dd4fdb0] [c000000000010eac] kernel_init+0x30/0x194 [ 60.419325][ C8] [c00000003dd4fe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74 [ 60.419363][ C8] Instruction dump: [ 60.419382][ C8] 7d075078 7ce74b78 7ce0f9ad 40c2fff0 7e449378 = 7fc3f378 4b03531d 60000000=20 [ 60.419416][ C8] 48000080 3920ffff 39400001 39000000 <7e00f8a8> = 7e075039 40c2fff8 7e074878=20 [ 98.908889][ C8] rcu: INFO: rcu_sched self-detected stall on CPU [ 98.908933][ C8] rcu: 8-....: (6500 ticks this GP) idle=3D522/1/0x4000000000000002 softirq=3D132/132 fqs=3D3250=20 [ 98.908963][ C8] (t=3D6501 jiffies g=3D-719 q=3D510) [ 98.908984][ C8] NMI backtrace for cpu 8 [ 98.909012][ C8] CPU: 8 PID: 1 Comm: swapper/0 Tainted: G L 5.6.0-rc4-next-20200303+ #7 [ 98.909025][ C8] Call Trace: [ 98.909046][ C8] [c00000003dd4f360] [c000000000970fe0] dump_stack+0xf4/0x164 (unreliable) [ 98.909070][ C8] [c00000003dd4f3b0] [c00000000097dcf4] nmi_cpu_backtrace+0x1b4/0x1e0 [ 98.909084][ C8] [c00000003dd4f450] [c00000000097df48] nmi_trigger_cpumask_backtrace+0x228/0x2c0 [ 98.909118][ C8] [c00000003dd4f500] [c000000000057bf8] arch_trigger_cpumask_backtrace+0x28/0x40 [ 98.909152][ C8] [c00000003dd4f520] [c000000000202dd4] rcu_dump_cpu_stacks+0x1c4/0x234 [ 98.909184][ C8] [c00000003dd4f5a0] [c000000000201634] rcu_sched_clock_irq+0xd54/0x1130 [ 98.909207][ C8] [c00000003dd4f6c0] [c000000000217068] update_process_times+0x48/0xb0 [ 98.909239][ C8] [c00000003dd4f6f0] [c0000000002358b4] tick_sched_handle+0x34/0xb0 [ 98.909262][ C8] [c00000003dd4f720] [c0000000002361d8] tick_sched_timer+0x68/0xe0 [ 98.909284][ C8] [c00000003dd4f760] [c000000000219768] __hrtimer_run_queues+0x528/0xa60 [ 98.909306][ C8] [c00000003dd4f880] [c00000000021ab58] hrtimer_interrupt+0x128/0x330 [ 98.909329][ C8] [c00000003dd4f930] [c00000000002e1b4] timer_interrupt+0x264/0x680 [ 98.909352][ C8] [c00000003dd4f9c0] [c000000000009264] decrementer_common+0x124/0x130 [ 98.909366][ C8] --- interrupt: 901 at = debug_vm_pgtable+0x7a8/0xbb4 [ 98.909366][ C8] LR =3D debug_vm_pgtable+0x6a0/0xbb4 [ 98.909402][ C8] [c00000003dd4fcc0] [c00000000103d994] debug_vm_pgtable+0x528/0xbb4 (unreliable) [ 98.909435][ C8] [c00000003dd4fdb0] [c000000000010eac] kernel_init+0x30/0x194 [ 98.909467][ C8] [c00000003dd4fe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74 [ 124.418885][ C8] watchdog: BUG: soft lockup - CPU#8 stuck for 22s! [swapper/0:1] [ 124.418914][ C8] Modules linked in: [ 124.418926][ C8] irq event stamp: 2937938 [ 124.418940][ C8] hardirqs last enabled at (2937937): = [] fast_exc_return_irq+0x28/0x34 [ 124.418964][ C8] hardirqs last disabled at (2937938): = [] decrementer_common+0x10c/0x130 [ 124.418980][ C8] softirqs last enabled at (2937936): = [] __do_softirq+0x640/0x8c8 [ 124.419013][ C8] softirqs last disabled at (2937929): = [] irq_exit+0x16c/0x1d0 [ 124.419036][ C8] CPU: 8 PID: 1 Comm: swapper/0 Tainted: G L 5.6.0-rc4-next-20200303+ #7 [ 124.419059][ C8] NIP: c00000000103dc14 LR: c00000000103db0c CTR: 0000000000000000 [ 124.419080][ C8] REGS: c00000003dd4fa30 TRAP: 0901 Tainted: G L (5.6.0-rc4-next-20200303+) [ 124.419103][ C8] MSR: 9000000000009033 = CR: 42000222 XER: 00000000 [ 124.419121][ C8] CFAR: c00000000103dc1c IRQMASK: 0=20 [ 124.419121][ C8] GPR00: c00000000103db0c c00000003dd4fcc0 = c000000001657d00 05210001000000c0=20 [ 124.419121][ C8] GPR04: 8000000000000105 000000000000000a = 00000000f4d9864c 0000000000000001=20 [ 124.419121][ C8] GPR08: 0000000000000000 ffffffffffffffff = 0000000000000001 00000000000a0000=20 [ 124.419121][ C8] GPR12: 0000000000000000 c000001fffff9880=20 [ 124.419234][ C8] NIP [c00000000103dc14] = debug_vm_pgtable+0x7a8/0xbb4 [ 124.419254][ C8] LR [c00000000103db0c] = debug_vm_pgtable+0x6a0/0xbb4 [ 124.419274][ C8] Call Trace: [ 124.419291][ C8] [c00000003dd4fcc0] [c00000000103d994] debug_vm_pgtable+0x528/0xbb4 (unreliable) [ 124.419324][ C8] [c00000003dd4fdb0] [c000000000010eac] kernel_init+0x30/0x194 [ 124.419347][ C8] [c00000003dd4fe20] [c00000000000b748] ret_from_kernel_thread+0x5c/0x74 [ 124.419359][ C8] Instruction dump: [ 124.419378][ C8] 7d075078 7ce74b78 7ce0f9ad 40c2fff0 7e449378 = 7fc3f378 4b03531d 60000000=20 [ 124.419412][ C8] 48000080 3920ffff 39400001 39000000 <7e00f8a8> = 7e075039 40c2fff8 7e074878 >=20 > mm/debug_vm_pgtable.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) >=20 > diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c > index 96dd7d574cef..c310f52c2b80 100644 > --- a/mm/debug_vm_pgtable.c > +++ b/mm/debug_vm_pgtable.c > @@ -250,13 +250,14 @@ static void __init pgd_populate_tests(struct = mm_struct *mm, pgd_t *pgdp, > } > #endif >=20 > -static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep) > +static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep, > + unsigned long vaddr) > { > pte_t pte =3D READ_ONCE(*ptep); >=20 > pte =3D __pte(pte_val(pte) | RANDOM_ORVALUE); > WRITE_ONCE(*ptep, pte); > - pte_clear(mm, 0, ptep); > + pte_clear(mm, vaddr, ptep); > pte =3D READ_ONCE(*ptep); > WARN_ON(!pte_none(pte)); > } > @@ -302,6 +303,7 @@ static unsigned long __init get_random_vaddr(void) > void __init debug_vm_pgtable(void) > { > struct mm_struct *mm; > + spinlock_t *uninitialized_var(ptl); > pgd_t *pgdp; > p4d_t *p4dp, *saved_p4dp; > pud_t *pudp, *saved_pudp; > @@ -344,7 +346,7 @@ void __init debug_vm_pgtable(void) > p4dp =3D p4d_alloc(mm, pgdp, vaddr); > pudp =3D pud_alloc(mm, p4dp, vaddr); > pmdp =3D pmd_alloc(mm, pudp, vaddr); > - ptep =3D pte_alloc_map(mm, pmdp, vaddr); > + ptep =3D pte_alloc_map_lock(mm, pmdp, vaddr, &ptl); >=20 > /* > * Save all the page table page addresses as the page table > @@ -364,13 +366,13 @@ void __init debug_vm_pgtable(void) > p4d_basic_tests(p4d_aligned, prot); > pgd_basic_tests(pgd_aligned, prot); >=20 > - pte_clear_tests(mm, ptep); > + 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); >=20 > - pte_unmap(ptep); > + pte_unmap_unlock(ptep, ptl); >=20 > pmd_populate_tests(mm, pmdp, saved_ptep); > pud_populate_tests(mm, pudp, saved_pmdp); > --=20 > 2.20.1