From: Zong Li <zongbox@gmail.com>
To: Steven Price <steven.price@arm.com>
Cc: linux-mm@kvack.org, "Andy Lutomirski" <luto@kernel.org>,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Ingo Molnar" <mingo@redhat.com>,
"James Morse" <james.morse@arm.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Will Deacon" <will@kernel.org>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
linux-arm-kernel@lists.infradead.org,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"Mark Rutland" <Mark.Rutland@arm.com>,
"Liang, Kan" <kan.liang@linux.intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>
Subject: Re: [PATCH v12 12/22] mm: pagewalk: Allow walking without vma
Date: Thu, 24 Oct 2019 21:05:41 +0800 [thread overview]
Message-ID: <CA+ZOyaiE2w686TmWWPT6tzu1MR3Fkm805k2hY1_VMfAnAwQPuQ@mail.gmail.com> (raw)
In-Reply-To: <20191018101248.33727-13-steven.price@arm.com>
Steven Price <steven.price@arm.com> 於 2019年10月19日 週六 下午4:12寫道：
>
> Since 48684a65b4e3: "mm: pagewalk: fix misbehavior of walk_page_range
> for vma(VM_PFNMAP)", page_table_walk() will report any kernel area as
> a hole, because it lacks a vma.
>
> This means each arch has re-implemented page table walking when needed,
> for example in the per-arch ptdump walker.
>
> Remove the requirement to have a vma except when trying to split huge
> pages.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> mm/pagewalk.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index fc4d98a3a5a0..4139e9163aee 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -38,7 +38,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
> do {
> again:
> next = pmd_addr_end(addr, end);
> - if (pmd_none(*pmd) || !walk->vma) {
> + if (pmd_none(*pmd)) {
> if (ops->pte_hole)
> err = ops->pte_hole(addr, next, walk);
> if (err)
> @@ -61,9 +61,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
> if (!ops->pte_entry)
> continue;
>
> - split_huge_pmd(walk->vma, pmd, addr);
> - if (pmd_trans_unstable(pmd))
> - goto again;
> + if (walk->vma) {
> + split_huge_pmd(walk->vma, pmd, addr);
> + if (pmd_trans_unstable(pmd))
> + goto again;
> + } else if (pmd_leaf(*pmd)) {
> + continue;
> + }
> +
> err = walk_pte_range(pmd, addr, next, walk);
> if (err)
> break;
> @@ -84,7 +89,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
> do {
> again:
> next = pud_addr_end(addr, end);
> - if (pud_none(*pud) || !walk->vma) {
> + if (pud_none(*pud)) {
> if (ops->pte_hole)
> err = ops->pte_hole(addr, next, walk);
> if (err)
> @@ -98,9 +103,13 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
> break;
> }
>
> - split_huge_pud(walk->vma, pud, addr);
> - if (pud_none(*pud))
> - goto again;
> + if (walk->vma) {
> + split_huge_pud(walk->vma, pud, addr);
> + if (pud_none(*pud))
> + goto again;
> + } else if (pud_leaf(*pud)) {
> + continue;
> + }
>
> if (ops->pmd_entry || ops->pte_entry)
> err = walk_pmd_range(pud, addr, next, walk);
> --
> 2.20.1
>
It's good to me.
Tested-by: Zong Li <zong.li@sifive.com>
next prev parent reply other threads:[~2019-10-24 13:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191018101248.33727-1-steven.price@arm.com>
[not found] ` <20191018101248.33727-8-steven.price@arm.com>
2019-10-18 15:57 ` [PATCH v12 07/22] riscv: mm: Add p?d_leaf() definitions Christoph Hellwig
[not found] ` <20191018101248.33727-13-steven.price@arm.com>
2019-10-24 13:05 ` Zong Li [this message]
[not found] ` <20191018101248.33727-14-steven.price@arm.com>
2019-10-24 13:06 ` [PATCH v12 13/22] mm: pagewalk: Add test_p?d callbacks Zong Li
[not found] ` <20191018101248.33727-12-steven.price@arm.com>
2019-10-24 13:06 ` [PATCH v12 11/22] mm: pagewalk: Add p4d_entry() and pgd_entry() Zong Li
[not found] ` <20191018101248.33727-15-steven.price@arm.com>
2019-10-24 13:07 ` [PATCH v12 14/22] mm: pagewalk: Add 'depth' parameter to pte_hole Zong Li
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