From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org,
mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
linux-riscv <linux-riscv@lists.infradead.org>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
Vineet Gupta <vgupta@synopsys.com>
Subject: Re: [PATCH v4 00/13] mm/debug_vm_pgtable fixes
Date: Fri, 4 Sep 2020 18:01:15 +0200 [thread overview]
Message-ID: <20200904180115.07ee5f00@thinkpad> (raw)
In-Reply-To: <20200904172647.002113d3@thinkpad>
On Fri, 4 Sep 2020 17:26:47 +0200
Gerald Schaefer <gerald.schaefer@linux.ibm.com> wrote:
> On Fri, 4 Sep 2020 12:18:05 +0530
> Anshuman Khandual <anshuman.khandual@arm.com> wrote:
>
> >
> >
> > On 09/02/2020 05:12 PM, Aneesh Kumar K.V wrote:
> > > This patch series includes fixes for debug_vm_pgtable test code so that
> > > they follow page table updates rules correctly. The first two patches introduce
> > > changes w.r.t ppc64. The patches are included in this series for completeness. We can
> > > merge them via ppc64 tree if required.
> > >
> > > Hugetlb test is disabled on ppc64 because that needs larger change to satisfy
> > > page table update rules.
> > >
> > > These tests are broken w.r.t page table update rules and results in kernel
> > > crash as below.
> > >
> > > [ 21.083519] kernel BUG at arch/powerpc/mm/pgtable.c:304!
> > > cpu 0x0: Vector: 700 (Program Check) at [c000000c6d1e76c0]
> > > pc: c00000000009a5ec: assert_pte_locked+0x14c/0x380
> > > lr: c0000000005eeeec: pte_update+0x11c/0x190
> > > sp: c000000c6d1e7950
> > > msr: 8000000002029033
> > > current = 0xc000000c6d172c80
> > > paca = 0xc000000003ba0000 irqmask: 0x03 irq_happened: 0x01
> > > pid = 1, comm = swapper/0
> > > kernel BUG at arch/powerpc/mm/pgtable.c:304!
> > > [link register ] c0000000005eeeec pte_update+0x11c/0x190
> > > [c000000c6d1e7950] 0000000000000001 (unreliable)
> > > [c000000c6d1e79b0] c0000000005eee14 pte_update+0x44/0x190
> > > [c000000c6d1e7a10] c000000001a2ca9c pte_advanced_tests+0x160/0x3d8
> > > [c000000c6d1e7ab0] c000000001a2d4fc debug_vm_pgtable+0x7e8/0x1338
> > > [c000000c6d1e7ba0] c0000000000116ec do_one_initcall+0xac/0x5f0
> > > [c000000c6d1e7c80] c0000000019e4fac kernel_init_freeable+0x4dc/0x5a4
> > > [c000000c6d1e7db0] c000000000012474 kernel_init+0x24/0x160
> > > [c000000c6d1e7e20] c00000000000cbd0 ret_from_kernel_thread+0x5c/0x6c
> > >
> > > With DEBUG_VM disabled
> > >
> > > [ 20.530152] BUG: Kernel NULL pointer dereference on read at 0x00000000
> > > [ 20.530183] Faulting instruction address: 0xc0000000000df330
> > > cpu 0x33: Vector: 380 (Data SLB Access) at [c000000c6d19f700]
> > > pc: c0000000000df330: memset+0x68/0x104
> > > lr: c00000000009f6d8: hash__pmdp_huge_get_and_clear+0xe8/0x1b0
> > > sp: c000000c6d19f990
> > > msr: 8000000002009033
> > > dar: 0
> > > current = 0xc000000c6d177480
> > > paca = 0xc00000001ec4f400 irqmask: 0x03 irq_happened: 0x01
> > > pid = 1, comm = swapper/0
> > > [link register ] c00000000009f6d8 hash__pmdp_huge_get_and_clear+0xe8/0x1b0
> > > [c000000c6d19f990] c00000000009f748 hash__pmdp_huge_get_and_clear+0x158/0x1b0 (unreliable)
> > > [c000000c6d19fa10] c0000000019ebf30 pmd_advanced_tests+0x1f0/0x378
> > > [c000000c6d19fab0] c0000000019ed088 debug_vm_pgtable+0x79c/0x1244
> > > [c000000c6d19fba0] c0000000000116ec do_one_initcall+0xac/0x5f0
> > > [c000000c6d19fc80] c0000000019a4fac kernel_init_freeable+0x4dc/0x5a4
> > > [c000000c6d19fdb0] c000000000012474 kernel_init+0x24/0x160
> > > [c000000c6d19fe20] c00000000000cbd0 ret_from_kernel_thread+0x5c/0x6c
> > >
> > > Changes from v3:
> > > * Address review feedback
> > > * Move page table depost and withdraw patch after adding pmdlock to avoid bisect failure.
> >
> > This version
> >
> > - Builds on x86, arm64, s390, arc, powerpc and riscv (defconfig with DEBUG_VM_PGTABLE)
> > - Runs on arm64 and x86 without any regression, atleast nothing that I have noticed
> > - Will be great if this could get tested on s390, arc, riscv, ppc32 platforms as well
>
> When I quickly tested v3, it worked fine, but now it turned out to
> only work fine "sometimes", both v3 and v4. I need to look into it
> further, but so far it seems related to the hugetlb_advanced_tests().
>
> I guess there was already some discussion on this test, but we did
> not receive all of the thread(s). Please always add at least
> linux-s390@vger.kernel.org and maybe myself and Vasily Gorbik <gor@linux.ibm.com>
> for further discussions.
BTW, with myself I mean the new address gerald.schaefer@linux.ibm.com.
The old gerald.schaefer@de.ibm.com seems to work (again), but is not
very reliable.
BTW2, a quick test with this change (so far) made the issues on s390
go away:
@@ -1069,7 +1074,7 @@ static int __init debug_vm_pgtable(void)
spin_unlock(ptl);
#ifndef CONFIG_PPC_BOOK3S_64
- hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
+ hugetlb_advanced_tests(mm, vma, (pte_t *) pmdp, pmd_aligned, vaddr, prot);
#endif
spin_lock(&mm->page_table_lock);
That would more match the "pte_t pointer" usage for hugetlb code,
i.e. just cast a pmd_t pointer to it. Also changed to pmd_aligned,
but I think the root cause is the pte_t pointer.
Not entirely sure though if that would really be the correct fix.
I somehow lost whatever little track I had about what these tests
really want to check, and if that would still be valid with that
change.
next prev parent reply other threads:[~2020-09-04 16:01 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-02 11:42 [PATCH v4 00/13] mm/debug_vm_pgtable fixes Aneesh Kumar K.V
2020-09-02 11:42 ` [PATCH v4 01/13] powerpc/mm: Add DEBUG_VM WARN for pmd_clear Aneesh Kumar K.V
2020-09-02 11:42 ` [PATCH v4 02/13] powerpc/mm: Move setting pte specific flags to pfn_pte Aneesh Kumar K.V
2020-09-02 12:30 ` Christophe Leroy
2020-09-02 11:42 ` [PATCH v4 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value Aneesh Kumar K.V
2020-09-04 4:03 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 04/13] mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support Aneesh Kumar K.V
2020-09-02 12:40 ` Christophe Leroy
2020-09-02 12:53 ` Aneesh Kumar K.V
2020-09-04 4:08 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 05/13] mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with CONFIG_NUMA_BALANCING Aneesh Kumar K.V
2020-09-04 4:09 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 06/13] mm/debug_vm_pgtable/THP: Mark the pte entry huge before using set_pmd/pud_at Aneesh Kumar K.V
2020-09-04 5:21 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry Aneesh Kumar K.V
2020-09-04 5:34 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 08/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together Aneesh Kumar K.V
2020-09-04 3:58 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 09/13] mm/debug_vm_pgtable/locks: Take correct page table lock Aneesh Kumar K.V
2020-09-04 5:39 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 10/13] mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP Aneesh Kumar K.V
2020-09-04 4:21 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries Aneesh Kumar K.V
2020-09-04 6:03 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 12/13] mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64 Aneesh Kumar K.V
2020-09-04 6:19 ` Anshuman Khandual
2020-09-02 11:42 ` [PATCH v4 13/13] mm/debug_vm_pgtable: Avoid none pte in pte_clear_test Aneesh Kumar K.V
2020-09-11 2:13 ` Nathan Chancellor
2020-09-11 5:21 ` Aneesh Kumar K.V
2020-09-23 3:14 ` Anshuman Khandual
2020-10-11 20:02 ` Guenter Roeck
2020-10-12 4:29 ` Aneesh Kumar K.V
2020-09-02 11:46 ` Aneesh Kumar K.V
2020-09-04 4:16 ` Anshuman Khandual
2020-09-04 6:48 ` [PATCH v4 00/13] mm/debug_vm_pgtable fixes Anshuman Khandual
2020-09-04 15:26 ` Gerald Schaefer
2020-09-04 16:01 ` Gerald Schaefer [this message]
2020-09-04 17:53 ` Gerald Schaefer
2020-09-09 8:38 ` Anshuman Khandual
2020-09-08 15:39 ` Gerald Schaefer
2020-09-09 6:08 ` Aneesh Kumar K.V
2020-09-09 11:16 ` Gerald Schaefer
2020-09-09 8:15 ` Anshuman Khandual
2020-09-09 11:10 ` Gerald Schaefer
2020-09-09 8:08 ` Anshuman Khandual
2020-09-09 11:36 ` Gerald Schaefer
2020-09-13 11:03 ` [PATCH] mm/debug_vm_pgtable: Avoid doing memory allocation with pgtable_t mapped Aneesh Kumar K.V
2020-09-13 13:42 ` Matthew Wilcox
2020-10-13 20:58 ` [PATCH v4 00/13] mm/debug_vm_pgtable fixes Andrew Morton
2020-10-14 3:15 ` Aneesh Kumar K.V
2020-10-14 20:36 ` Andrew Morton
2020-10-15 2:59 ` Anshuman Khandual
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