From: Mike Kravetz <mike.kravetz@oracle.com>
To: "manish.mishra" <manish.mishra@nutanix.com>
Cc: James Houghton <jthoughton@google.com>,
Muchun Song <songmuchun@bytedance.com>,
Peter Xu <peterx@redhat.com>,
David Hildenbrand <david@redhat.com>,
David Rientjes <rientjes@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Mina Almasry <almasrymina@google.com>, Jue Wang <juew@google.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 11/26] hugetlb: add hugetlb_walk_to to do PT walks
Date: Thu, 7 Jul 2022 16:03:44 -0700 [thread overview]
Message-ID: <YsdmUJcRoLDEHvNK@monkey> (raw)
In-Reply-To: <ac95fce2-b095-62ff-7f87-d803572e39f0@nutanix.com>
On 06/27/22 18:37, manish.mishra wrote:
>
> On 24/06/22 11:06 pm, James Houghton wrote:
> > This adds it for architectures that use GENERAL_HUGETLB, including x86.
I expect this will be used in arch independent code and there will need to
be at least a stub for all architectures?
> >
> > Signed-off-by: James Houghton <jthoughton@google.com>
> > ---
> > include/linux/hugetlb.h | 2 ++
> > mm/hugetlb.c | 45 +++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 47 insertions(+)
> >
> > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> > index e7a6b944d0cc..605aa19d8572 100644
> > --- a/include/linux/hugetlb.h
> > +++ b/include/linux/hugetlb.h
> > @@ -258,6 +258,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
> > unsigned long addr, unsigned long sz);
> > pte_t *huge_pte_offset(struct mm_struct *mm,
> > unsigned long addr, unsigned long sz);
> > +int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
> > + unsigned long addr, unsigned long sz, bool stop_at_none);
> > int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
> > unsigned long *addr, pte_t *ptep);
> > void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 557b0afdb503..3ec2a921ee6f 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -6981,6 +6981,51 @@ pte_t *huge_pte_offset(struct mm_struct *mm,
> > return (pte_t *)pmd;
> > }
>
>
> not strong feeling but this name looks confusing to me as it does
>
> not only walk over page-tables but can also alloc.
>
Somewhat agree. With this we have:
- huge_pte_offset to walk/lookup a pte
- huge_pte_alloc to allocate ptes
- hugetlb_walk_to which does some/all of both
Do not see anything obviously wrong with the routine, but future
direction would be to combine/clean up these routines with similar
purpose.
--
Mike Kravetz
> > +int hugetlb_walk_to(struct mm_struct *mm, struct hugetlb_pte *hpte,
> > + unsigned long addr, unsigned long sz, bool stop_at_none)
> > +{
> > + pte_t *ptep;
> > +
> > + if (!hpte->ptep) {
> > + pgd_t *pgd = pgd_offset(mm, addr);
> > +
> > + if (!pgd)
> > + return -ENOMEM;
> > + ptep = (pte_t *)p4d_alloc(mm, pgd, addr);
> > + if (!ptep)
> > + return -ENOMEM;
> > + hugetlb_pte_populate(hpte, ptep, P4D_SHIFT);
> > + }
> > +
> > + while (hugetlb_pte_size(hpte) > sz &&
> > + !hugetlb_pte_present_leaf(hpte) &&
> > + !(stop_at_none && hugetlb_pte_none(hpte))) {
>
> Should this ordering of if-else condition be in reverse, i mean it will look
>
> more natural and possibly less condition checks as we go from top to bottom.
>
> > + if (hpte->shift == PMD_SHIFT) {
> > + ptep = pte_alloc_map(mm, (pmd_t *)hpte->ptep, addr);
> > + if (!ptep)
> > + return -ENOMEM;
> > + hpte->shift = PAGE_SHIFT;
> > + hpte->ptep = ptep;
> > + } else if (hpte->shift == PUD_SHIFT) {
> > + ptep = (pte_t *)pmd_alloc(mm, (pud_t *)hpte->ptep,
> > + addr);
> > + if (!ptep)
> > + return -ENOMEM;
> > + hpte->shift = PMD_SHIFT;
> > + hpte->ptep = ptep;
> > + } else if (hpte->shift == P4D_SHIFT) {
> > + ptep = (pte_t *)pud_alloc(mm, (p4d_t *)hpte->ptep,
> > + addr);
> > + if (!ptep)
> > + return -ENOMEM;
> > + hpte->shift = PUD_SHIFT;
> > + hpte->ptep = ptep;
> > + } else
> > + BUG();
> > + }
> > + return 0;
> > +}
> > +
> > #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
> > #ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
next prev parent reply other threads:[~2022-07-07 23:03 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 17:36 [RFC PATCH 00/26] hugetlb: Introduce HugeTLB high-granularity mapping James Houghton
2022-06-24 17:36 ` [RFC PATCH 01/26] hugetlb: make hstate accessor functions const James Houghton
2022-06-24 18:43 ` Mina Almasry
[not found] ` <e55f90f5-ba14-5d6e-8f8f-abf731b9095e@nutanix.com>
2022-06-27 12:09 ` manish.mishra
2022-06-28 17:08 ` James Houghton
2022-06-29 6:18 ` Muchun Song
2022-06-24 17:36 ` [RFC PATCH 02/26] hugetlb: sort hstates in hugetlb_init_hstates James Houghton
2022-06-24 18:51 ` Mina Almasry
2022-06-27 12:08 ` manish.mishra
2022-06-28 15:35 ` James Houghton
2022-06-27 18:42 ` Mike Kravetz
2022-06-28 15:40 ` James Houghton
2022-06-29 6:39 ` Muchun Song
2022-06-29 21:06 ` Mike Kravetz
2022-06-29 21:13 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 03/26] hugetlb: add make_huge_pte_with_shift James Houghton
2022-06-24 19:01 ` Mina Almasry
2022-06-27 12:13 ` manish.mishra
2022-06-24 17:36 ` [RFC PATCH 04/26] hugetlb: make huge_pte_lockptr take an explicit shift argument James Houghton
2022-06-27 12:26 ` manish.mishra
2022-06-27 20:51 ` Mike Kravetz
2022-06-28 15:29 ` James Houghton
2022-06-29 6:09 ` Muchun Song
2022-06-29 21:03 ` Mike Kravetz
2022-06-29 21:39 ` James Houghton
2022-06-29 22:24 ` Mike Kravetz
2022-06-30 9:35 ` Muchun Song
2022-06-30 16:23 ` James Houghton
2022-06-30 17:40 ` Mike Kravetz
2022-07-01 3:32 ` Muchun Song
2022-06-24 17:36 ` [RFC PATCH 05/26] hugetlb: add CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING James Houghton
2022-06-27 12:28 ` manish.mishra
2022-06-28 20:03 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 06/26] mm: make free_p?d_range functions public James Houghton
2022-06-27 12:31 ` manish.mishra
2022-06-28 20:35 ` Mike Kravetz
2022-07-12 20:52 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 07/26] hugetlb: add hugetlb_pte to track HugeTLB page table entries James Houghton
2022-06-27 12:47 ` manish.mishra
2022-06-29 16:28 ` James Houghton
2022-06-28 20:25 ` Mina Almasry
2022-06-29 16:42 ` James Houghton
2022-06-28 20:44 ` Mike Kravetz
2022-06-29 16:24 ` James Houghton
2022-07-11 23:32 ` Mike Kravetz
2022-07-12 9:42 ` Dr. David Alan Gilbert
2022-07-12 17:51 ` Mike Kravetz
2022-07-15 16:35 ` Peter Xu
2022-07-15 21:52 ` Axel Rasmussen
2022-07-15 23:03 ` Peter Xu
2022-09-08 17:38 ` Peter Xu
2022-09-08 17:54 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 08/26] hugetlb: add hugetlb_free_range to free PT structures James Houghton
2022-06-27 12:52 ` manish.mishra
2022-06-28 20:27 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 09/26] hugetlb: add hugetlb_hgm_enabled James Houghton
2022-06-27 12:55 ` manish.mishra
2022-06-28 20:33 ` Mina Almasry
2022-09-08 18:07 ` Peter Xu
2022-09-08 18:13 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 10/26] hugetlb: add for_each_hgm_shift James Houghton
2022-06-27 13:01 ` manish.mishra
2022-06-28 21:58 ` Mina Almasry
2022-07-07 21:39 ` Mike Kravetz
2022-07-08 15:52 ` James Houghton
2022-07-09 21:55 ` Mina Almasry
2022-06-24 17:36 ` [RFC PATCH 11/26] hugetlb: add hugetlb_walk_to to do PT walks James Houghton
2022-06-27 13:07 ` manish.mishra
2022-07-07 23:03 ` Mike Kravetz [this message]
2022-09-08 18:20 ` Peter Xu
2022-06-24 17:36 ` [RFC PATCH 12/26] hugetlb: add HugeTLB splitting functionality James Houghton
2022-06-27 13:50 ` manish.mishra
2022-06-29 16:10 ` James Houghton
2022-06-29 14:33 ` manish.mishra
2022-06-29 16:20 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 13/26] hugetlb: add huge_pte_alloc_high_granularity James Houghton
2022-06-29 14:11 ` manish.mishra
2022-06-24 17:36 ` [RFC PATCH 14/26] hugetlb: add HGM support for hugetlb_fault and hugetlb_no_page James Houghton
2022-06-29 14:40 ` manish.mishra
2022-06-29 15:56 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 15/26] hugetlb: make unmapping compatible with high-granularity mappings James Houghton
2022-07-19 10:19 ` manish.mishra
2022-07-19 15:58 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 16/26] hugetlb: make hugetlb_change_protection compatible with HGM James Houghton
2022-06-24 17:36 ` [RFC PATCH 17/26] hugetlb: update follow_hugetlb_page to support HGM James Houghton
2022-07-19 10:48 ` manish.mishra
2022-07-19 16:19 ` James Houghton
2022-06-24 17:36 ` [RFC PATCH 18/26] hugetlb: use struct hugetlb_pte for walk_hugetlb_range James Houghton
2022-06-24 17:36 ` [RFC PATCH 19/26] hugetlb: add HGM support for copy_hugetlb_page_range James Houghton
2022-07-11 23:41 ` Mike Kravetz
2022-07-12 17:19 ` James Houghton
2022-07-12 18:06 ` Mike Kravetz
2022-07-15 21:39 ` Axel Rasmussen
2022-06-24 17:36 ` [RFC PATCH 20/26] hugetlb: add support for high-granularity UFFDIO_CONTINUE James Houghton
2022-07-15 16:21 ` Peter Xu
2022-07-15 16:58 ` James Houghton
2022-07-15 17:20 ` Peter Xu
2022-07-20 20:58 ` James Houghton
2022-07-21 19:09 ` Peter Xu
2022-07-21 19:44 ` James Houghton
2022-07-21 19:53 ` Peter Xu
2022-06-24 17:36 ` [RFC PATCH 21/26] hugetlb: add hugetlb_collapse James Houghton
2022-06-24 17:36 ` [RFC PATCH 22/26] madvise: add uapi for HugeTLB HGM collapse: MADV_COLLAPSE James Houghton
2022-06-24 17:36 ` [RFC PATCH 23/26] userfaultfd: add UFFD_FEATURE_MINOR_HUGETLBFS_HGM James Houghton
2022-06-24 17:36 ` [RFC PATCH 24/26] arm64/hugetlb: add support for high-granularity mappings James Houghton
2022-06-24 17:36 ` [RFC PATCH 25/26] selftests: add HugeTLB HGM to userfaultfd selftest James Houghton
2022-06-24 17:36 ` [RFC PATCH 26/26] selftests: add HugeTLB HGM to KVM demand paging selftest James Houghton
2022-06-24 18:29 ` [RFC PATCH 00/26] hugetlb: Introduce HugeTLB high-granularity mapping Matthew Wilcox
2022-06-27 16:36 ` James Houghton
2022-06-27 17:56 ` Dr. David Alan Gilbert
2022-06-27 20:31 ` James Houghton
2022-06-28 0:04 ` Nadav Amit
2022-06-30 19:21 ` Peter Xu
2022-07-01 5:54 ` Nadav Amit
2022-06-28 8:20 ` Dr. David Alan Gilbert
2022-06-30 16:09 ` Peter Xu
2022-06-24 18:41 ` Mina Almasry
2022-06-27 16:27 ` James Houghton
2022-06-28 14:17 ` Muchun Song
2022-06-28 17:26 ` Mina Almasry
2022-06-28 17:56 ` Dr. David Alan Gilbert
2022-06-29 18:31 ` James Houghton
2022-06-29 20:39 ` Axel Rasmussen
2022-06-24 18:47 ` Matthew Wilcox
2022-06-27 16:48 ` James Houghton
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