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Date: Mon, 23 Mar 2020 17:23:15 -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 Mon, Mar 23, 2020 at 5:17 PM Mike Kravetz <mike.kravetz@...cle.com> wrote:
>
> On 3/23/20 5:01 PM, Mina Almasry wrote:
> > 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?
>
> Correct.
>
> > Does
> > that mean the warning prints if you specify this size?
>
> The code which adds the default hstate (in hugetlb_init) runs after this
> code which is reading/processing command line options. So, the case you
> are concerned with will not happen.
>
> Thanks for taking a look,
> --
> Mike Kravetz
>
> > '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
Acked-By: Mina Almasry <almasrymina@...gle.com>
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