From: Steven Price <steven.price@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>, linux-mm@kvack.org
Cc: "Mark Rutland" <Mark.Rutland@arm.com>,
x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
linux-kernel@vger.kernel.org,
"Jérôme Glisse" <jglisse@redhat.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Andy Lutomirski" <luto@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
"James Morse" <james.morse@arm.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Will Deacon" <will@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org, "Liang,
Kan" <kan.liang@linux.intel.com>
Subject: Re: [PATCH v9 13/21] mm: pagewalk: Add test_p?d callbacks
Date: Mon, 29 Jul 2019 13:34:48 +0100 [thread overview]
Message-ID: <df6f5233-6630-2d21-ad38-2520644c0c87@arm.com> (raw)
In-Reply-To: <b74e545f-cbe0-9dd0-004c-5919e5cabb6f@arm.com>
On 28/07/2019 14:41, Anshuman Khandual wrote:
>
>
> On 07/22/2019 09:12 PM, Steven Price wrote:
>> It is useful to be able to skip parts of the page table tree even when
>> walking without VMAs. Add test_p?d callbacks similar to test_walk but
>> which are called just before a table at that level is walked. If the
>> callback returns non-zero then the entire table is skipped.
>>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>> include/linux/mm.h | 11 +++++++++++
>> mm/pagewalk.c | 24 ++++++++++++++++++++++++
>> 2 files changed, 35 insertions(+)
>>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index b22799129128..325a1ca6f820 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -1447,6 +1447,11 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
>> * value means "do page table walk over the current vma,"
>> * and a negative one means "abort current page table walk
>> * right now." 1 means "skip the current vma."
>> + * @test_pmd: similar to test_walk(), but called for every pmd.
>> + * @test_pud: similar to test_walk(), but called for every pud.
>> + * @test_p4d: similar to test_walk(), but called for every p4d.
>> + * Returning 0 means walk this part of the page tables,
>> + * returning 1 means to skip this range.
>> * @mm: mm_struct representing the target process of page table walk
>> * @vma: vma currently walked (NULL if walking outside vmas)
>> * @private: private data for callbacks' usage
>> @@ -1471,6 +1476,12 @@ struct mm_walk {
>> struct mm_walk *walk);
>> int (*test_walk)(unsigned long addr, unsigned long next,
>> struct mm_walk *walk);
>> + int (*test_pmd)(unsigned long addr, unsigned long next,
>> + pmd_t *pmd_start, struct mm_walk *walk);
>> + int (*test_pud)(unsigned long addr, unsigned long next,
>> + pud_t *pud_start, struct mm_walk *walk);
>> + int (*test_p4d)(unsigned long addr, unsigned long next,
>> + p4d_t *p4d_start, struct mm_walk *walk);
>> struct mm_struct *mm;
>> struct vm_area_struct *vma;
>> void *private;
>> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
>> index 1cbef99e9258..6bea79b95be3 100644
>> --- a/mm/pagewalk.c
>> +++ b/mm/pagewalk.c
>> @@ -32,6 +32,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>> unsigned long next;
>> int err = 0;
>>
>> + if (walk->test_pmd) {
>> + err = walk->test_pmd(addr, end, pmd_offset(pud, 0UL), walk);
>> + if (err < 0)
>> + return err;
>> + if (err > 0)
>> + return 0;
>> + }
>
> Though this attempts to match semantics with test_walk() and be comprehensive
> just wondering what are the real world situations when page walking need to be
> aborted based on error condition at a given page table level.
I'm not aware of a situation yet where aborting early is necessary - but
as you say this matches the semantics of test_walk() and was easy to
implement.
Steve
next prev parent reply other threads:[~2019-07-29 12:34 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-22 15:41 [PATCH v9 00/21] Generic page walk and ptdump Steven Price
2019-07-22 15:41 ` [PATCH v9 01/21] arc: mm: Add p?d_leaf() definitions Steven Price
2019-07-22 15:41 ` [PATCH v9 02/21] arm: " Steven Price
2019-07-22 15:41 ` [PATCH v9 03/21] arm64: " Steven Price
2019-07-22 15:41 ` [PATCH v9 04/21] mips: " Steven Price
2019-07-22 21:47 ` Paul Burton
2019-07-24 13:03 ` Steven Price
2019-07-22 15:41 ` [PATCH v9 05/21] powerpc: " Steven Price
2019-07-22 15:41 ` [PATCH v9 06/21] riscv: " Steven Price
2019-07-22 15:41 ` [PATCH v9 07/21] s390: " Steven Price
2019-07-22 15:41 ` [PATCH v9 08/21] sparc: " Steven Price
2019-07-22 15:41 ` [PATCH v9 09/21] x86: " Steven Price
2019-07-22 15:41 ` [PATCH v9 10/21] mm: Add generic p?d_leaf() macros Steven Price
2019-07-23 9:41 ` Mark Rutland
2019-07-24 13:48 ` Steven Price
2019-07-28 11:44 ` Anshuman Khandual
2019-07-29 11:38 ` Steven Price
2019-08-01 6:09 ` Anshuman Khandual
2019-08-01 12:22 ` Steven Price
2019-07-29 12:50 ` Mark Rutland
2019-08-01 6:13 ` Anshuman Khandual
2019-07-22 15:42 ` [PATCH v9 11/21] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-07-23 10:14 ` Mark Rutland
2019-07-24 13:53 ` Steven Price
2019-07-24 14:09 ` Mark Rutland
2019-07-28 12:33 ` Anshuman Khandual
2019-07-29 12:17 ` Steven Price
2019-07-22 15:42 ` [PATCH v9 12/21] mm: pagewalk: Allow walking without vma Steven Price
2019-07-28 14:20 ` Anshuman Khandual
2019-07-29 12:29 ` Steven Price
2019-08-01 6:41 ` Anshuman Khandual
2019-07-22 15:42 ` [PATCH v9 13/21] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-07-28 13:41 ` Anshuman Khandual
2019-07-29 12:34 ` Steven Price [this message]
2019-07-22 15:42 ` [PATCH v9 14/21] x86: mm: Don't display pages which aren't present in debugfs Steven Price
2019-07-22 15:42 ` [PATCH v9 15/21] x86: mm: Point to struct seq_file from struct pg_state Steven Price
2019-07-22 15:42 ` [PATCH v9 16/21] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-07-22 15:42 ` [PATCH v9 17/21] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-07-22 15:42 ` [PATCH v9 18/21] x86: mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-07-22 15:42 ` [PATCH v9 19/21] mm: Add generic ptdump Steven Price
2019-07-23 9:57 ` Mark Rutland
2019-07-24 16:36 ` Steven Price
2019-07-29 2:59 ` Anshuman Khandual
2019-07-29 13:56 ` Steven Price
2019-07-22 15:42 ` [PATCH v9 20/21] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-07-22 15:42 ` [PATCH v9 21/21] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-07-23 6:39 ` [PATCH v9 00/21] Generic page walk and ptdump Anshuman Khandual
2019-07-24 13:35 ` Steven Price
2019-07-25 9:09 ` Anshuman Khandual
2019-07-25 9:30 ` Will Deacon
2019-07-26 6:03 ` Anshuman Khandual
2019-07-25 10:15 ` Steven Price
2019-07-23 10:16 ` Mark Rutland
2019-07-24 13:35 ` Steven Price
2019-07-24 13:57 ` Thomas Gleixner
2019-07-24 14:07 ` Mark Rutland
2019-07-24 14:18 ` Steven Price
2019-07-24 14:37 ` Thomas Gleixner
2019-07-28 11:20 ` Anshuman Khandual
2019-07-29 11:32 ` Steven Price
2019-07-31 9:27 ` Sven Schnelle
2019-07-31 11:18 ` Steven Price
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