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Date: Mon, 23 Mar 2020 17:01:03 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Mike Kravetz <mike.kravetz@...cle.com>
Cc: Linux-MM <linux-mm@...ck.org>,
open list <linux-kernel@...r.kernel.org>,
linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
linux-doc@...r.kernel.org,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ibm.com>,
"David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Jonathan Corbet <corbet@....net>,
Longpeng <longpeng2@...wei.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 3/4] hugetlbfs: remove hugetlb_add_hstate() warning for
existing hstate
On Wed, Mar 18, 2020 at 3:07 PM Mike Kravetz <mike.kravetz@...cle.com> wrote:
>
> The routine hugetlb_add_hstate prints a warning if the hstate already
> exists. This was originally done as part of kernel command line
> parsing. If 'hugepagesz=' was specified more than once, the warning
> pr_warn("hugepagesz= specified twice, ignoring\n");
> would be printed.
>
> Some architectures want to enable all huge page sizes. They would
> call hugetlb_add_hstate for all supported sizes. However, this was
> done after command line processing and as a result hstates could have
> already been created for some sizes. To make sure no warning were
> printed, there would often be code like:
> if (!size_to_hstate(size)
> hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT)
>
> The only time we want to print the warning is as the result of command
> line processing. So, remove the warning from hugetlb_add_hstate and
> add it to the single arch independent routine processing "hugepagesz=".
> After this, calls to size_to_hstate() in arch specific code can be
> removed and hugetlb_add_hstate can be called without worrying about
> warning messages.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
> ---
> arch/arm64/mm/hugetlbpage.c | 16 ++++------------
> arch/powerpc/mm/hugetlbpage.c | 3 +--
> arch/riscv/mm/hugetlbpage.c | 2 +-
> arch/sparc/mm/init_64.c | 19 ++++---------------
> arch/x86/mm/hugetlbpage.c | 2 +-
> mm/hugetlb.c | 10 +++++++---
> 6 files changed, 18 insertions(+), 34 deletions(-)
>
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 4aa9534a45d7..050809e6f0a9 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -441,22 +441,14 @@ void huge_ptep_clear_flush(struct vm_area_struct *vma,
> clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
> }
>
> -static void __init add_huge_page_size(unsigned long size)
> -{
> - if (size_to_hstate(size))
> - return;
> -
> - hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> -}
> -
> static int __init hugetlbpage_init(void)
> {
> #ifdef CONFIG_ARM64_4K_PAGES
> - add_huge_page_size(PUD_SIZE);
> + hugetlb_add_hstate(ilog2(PUD_SIZE) - PAGE_SHIFT);
> #endif
> - add_huge_page_size(CONT_PMD_SIZE);
> - add_huge_page_size(PMD_SIZE);
> - add_huge_page_size(CONT_PTE_SIZE);
> + hugetlb_add_hstate(ilog2(CONT_PMD_SIZE) - PAGE_SHIFT);
> + hugetlb_add_hstate(ilog2(PMD_SIZE) - PAGE_SHIFT);
> + hugetlb_add_hstate(ilog2(CONT_PTE_SIZE) - PAGE_SHIFT);
>
> return 0;
> }
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 166960ba1236..f46464ba6fb4 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -584,8 +584,7 @@ static int __init add_huge_page_size(unsigned long long size)
> if (!arch_hugetlb_valid_size(size))
> return -EINVAL;
>
> - if (!size_to_hstate(size))
> - hugetlb_add_hstate(shift - PAGE_SHIFT);
> + hugetlb_add_hstate(shift - PAGE_SHIFT);
> return 0;
> }
>
> diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
> index bdf89d7eb714..beaa91941db8 100644
> --- a/arch/riscv/mm/hugetlbpage.c
> +++ b/arch/riscv/mm/hugetlbpage.c
> @@ -26,7 +26,7 @@ bool __init arch_hugetlb_valid_size(unsigned long long size)
> static __init int gigantic_pages_init(void)
> {
> /* With CONTIG_ALLOC, we can allocate gigantic pages at runtime */
> - if (IS_ENABLED(CONFIG_64BIT) && !size_to_hstate(1UL << PUD_SHIFT))
> + if (IS_ENABLED(CONFIG_64BIT))
> hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> return 0;
> }
> diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
> index 5c29203fd460..8f619edc8f8c 100644
> --- a/arch/sparc/mm/init_64.c
> +++ b/arch/sparc/mm/init_64.c
> @@ -325,23 +325,12 @@ static void __update_mmu_tsb_insert(struct mm_struct *mm, unsigned long tsb_inde
> }
>
> #ifdef CONFIG_HUGETLB_PAGE
> -static void __init add_huge_page_size(unsigned long size)
> -{
> - unsigned int order;
> -
> - if (size_to_hstate(size))
> - return;
> -
> - order = ilog2(size) - PAGE_SHIFT;
> - hugetlb_add_hstate(order);
> -}
> -
> static int __init hugetlbpage_init(void)
> {
> - add_huge_page_size(1UL << HPAGE_64K_SHIFT);
> - add_huge_page_size(1UL << HPAGE_SHIFT);
> - add_huge_page_size(1UL << HPAGE_256MB_SHIFT);
> - add_huge_page_size(1UL << HPAGE_2GB_SHIFT);
> + hugetlb_add_hstate(HPAGE_64K_SHIFT - PAGE_SHIFT);
> + hugetlb_add_hstate(HPAGE_SHIFT - PAGE_SHIFT);
> + hugetlb_add_hstate(HPAGE_256MB_SHIFT - PAGE_SHIFT);
> + hugetlb_add_hstate(HPAGE_2GB_SHIFT - PAGE_SHIFT);
>
> return 0;
> }
> diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
> index dd3ed09f6c23..8a3f586e1217 100644
> --- a/arch/x86/mm/hugetlbpage.c
> +++ b/arch/x86/mm/hugetlbpage.c
> @@ -195,7 +195,7 @@ bool __init arch_hugetlb_valid_size(unsigned long long size)
> static __init int gigantic_pages_init(void)
> {
> /* With compaction or CMA we can allocate gigantic pages at runtime */
> - if (boot_cpu_has(X86_FEATURE_GBPAGES) && !size_to_hstate(1UL << PUD_SHIFT))
> + if (boot_cpu_has(X86_FEATURE_GBPAGES))
> hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> return 0;
> }
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index cd4ec07080fb..cc85b4f156ca 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -3116,8 +3116,7 @@ static int __init hugetlb_init(void)
> }
>
> default_hstate_size = HPAGE_SIZE;
> - if (!size_to_hstate(default_hstate_size))
> - hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
> + hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
> }
> default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
> if (default_hstate_max_huge_pages) {
> @@ -3155,7 +3154,6 @@ void __init hugetlb_add_hstate(unsigned int order)
> unsigned long i;
>
> if (size_to_hstate(PAGE_SIZE << order)) {
> - pr_warn("hugepagesz= specified twice, ignoring\n");
> return;
> }
> BUG_ON(hugetlb_max_hstate >= HUGE_MAX_HSTATE);
> @@ -3231,6 +3229,12 @@ static int __init hugepagesz_setup(char *s)
> return 0;
> }
>
> + if (size_to_hstate(size)) {
> + pr_warn("HugeTLB: hugepagesz %s specified twice, ignoring\n",
> + saved_s);
> + return 0;
> + }
> +
Not too familiar with the code but I'm a bit confused by this print.
AFAICT this prints the warning when hugepagesz= refers to a hugepage
that is already added via hugetlb_add_hstate, but there is a default
hstate added here without the user specifying hugepagesz, no? Does
that mean the warning prints if you specify this size? Maybe then
clarify the message like:
'HugeTLB: hugepage size already supported: xxxxx' or
'HugeTLB: hugepage size xxxx specified twice or is default size, ignoring.'
Or don't print anything if it's the default size.
> hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> return 1;
> }
> --
> 2.24.1
>
>
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