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From: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: "linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	linux-mm@kvack.org, Vineet Gupta <vgupta@synopsys.com>,
	akpm@linux-foundation.org,
	"linux-snps-arc@lists.infradead.org"
	<linux-snps-arc@lists.infradead.org>,
	linuxppc-dev@lists.ozlabs.org,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Gerald Schaefer <gerald.schaefer@de.ibm.com>
Subject: Re: [PATCH v4 00/13] mm/debug_vm_pgtable fixes
Date: Wed, 9 Sep 2020 13:10:01 +0200
Message-ID: <20200909131001.7b733b3e@thinkpad> (raw)
In-Reply-To: <ac85fd77-bca1-3318-de0e-eea40558cbbd@arm.com>

On Wed, 9 Sep 2020 13:45:48 +0530
Anshuman Khandual <anshuman.khandual@arm.com> wrote:

[...]
> > 
> > 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.
> 
> Ideally, the pte_t pointer used here should be from huge_pte_alloc()
> not from pte_alloc_map_lock() as the case currently.

Ah, good point. I assumed that this would also always return casted
pmd etc. pointers, and never pte pointers. Unfortunately, that doesn't
seem to be true for all architectures, e.g. ia64, parisc, (some) powerpc,
where they really do a pte_alloc_map() for some reason.

I guess that means you cannot simply cast the pmd pointer, as suggested,
although I really do not understand how any architecture can work with
real ptes for hugepages. But that's fair, s390 also does some things that
nobody would expect or understand for other architectures...

So, for using huge_pte_alloc() you'd also need some size, maybe
iterating over hstates with for_each_hstate() could be an option,
if they are already initialized at that point. Then you have the
size(s) with huge_page_size(hstate) and can actually call the
hugetlb tests for all supported sizes, and with proper pointer
from huge_pte_alloc().

  reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02 11:42 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
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 [this message]
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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