From: James Houghton <jthoughton@google.com>
To: Peter Xu <peterx@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Muchun Song <songmuchun@bytedance.com>,
David Hildenbrand <david@redhat.com>,
David Rientjes <rientjes@google.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Mina Almasry <almasrymina@google.com>,
"Zach O'Keefe" <zokeefe@google.com>,
Manish Mishra <manish.mishra@nutanix.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Miaohe Lin <linmiaohe@huawei.com>, Yang Shi <shy828301@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 34/46] hugetlb: userfaultfd: when using MADV_SPLIT, round addresses to PAGE_SIZE
Date: Tue, 10 Jan 2023 09:50:59 -0500 [thread overview]
Message-ID: <CADrL8HXbTzX8T-S57mUQ8ggJ=DGMcQAxJapiQCFndqjPNLV=-Q@mail.gmail.com> (raw)
In-Reply-To: <Y7g6ihsCTIC765CO@x1n>
On Fri, Jan 6, 2023 at 10:13 AM Peter Xu <peterx@redhat.com> wrote:
>
> On Thu, Jan 05, 2023 at 10:18:32AM +0000, James Houghton wrote:
> > MADV_SPLIT enables HugeTLB HGM which allows for UFFDIO_CONTINUE in
> > PAGE_SIZE chunks. If a huge-page-aligned address were to be provided,
> > userspace would be completely unable to take advantage of HGM. That
> > would then require userspace to know to provide
> > UFFD_FEATURE_EXACT_ADDRESS.
> >
> > This patch would make it harder to make a mistake. Instead of requiring
> > userspace to provide UFFD_FEATURE_EXACT_ADDRESS, always provide a usable
> > address.
> >
> > Signed-off-by: James Houghton <jthoughton@google.com>
> > ---
> > mm/hugetlb.c | 31 +++++++++++++++----------------
> > 1 file changed, 15 insertions(+), 16 deletions(-)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 5af6db52f34e..5b6215e03fe1 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -5936,28 +5936,27 @@ static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma,
> > unsigned long addr,
> > unsigned long reason)
> > {
> > + u32 hash;
> > + struct vm_fault vmf;
> > +
> > /*
> > * Don't use the hpage-aligned address if the user has explicitly
> > * enabled HGM.
> > */
> > if (hugetlb_hgm_advised(vma) && reason == VM_UFFD_MINOR)
> > - haddr = address & PAGE_MASK;
> > -
> > - u32 hash;
> > - struct vm_fault vmf = {
> > - .vma = vma,
> > - .address = haddr,
> > - .real_address = addr,
> > - .flags = flags,
> > + haddr = addr & PAGE_MASK;
> >
> > - /*
> > - * Hard to debug if it ends up being
> > - * used by a callee that assumes
> > - * something about the other
> > - * uninitialized fields... same as in
> > - * memory.c
> > - */
> > - };
> > + vmf.vma = vma;
> > + vmf.address = haddr;
> > + vmf.real_address = addr;
> > + vmf.flags = flags;
>
> Const fields here:
>
> mm/hugetlb.c: In function ‘hugetlb_handle_userfault’:
> mm/hugetlb.c:5961:17: error: assignment of member ‘vma’ in read-only object
> 5961 | vmf.vma = vma;
> | ^
> mm/hugetlb.c:5962:21: error: assignment of member ‘address’ in read-only object
> 5962 | vmf.address = haddr;
> | ^
> mm/hugetlb.c:5963:26: error: assignment of member ‘real_address’ in read-only object
> 5963 | vmf.real_address = addr;
Thanks Peter for this and your other findings. Not sure why my
compiler (clang) let me do this. :/ Will send a v2 soon with this +
the other problems fixed.
next prev parent reply other threads:[~2023-01-10 14:51 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-05 10:17 [PATCH 00/46] Based on latest mm-unstable (85b44c25cd1e) James Houghton
2023-01-05 10:17 ` [PATCH 01/46] hugetlb: don't set PageUptodate for UFFDIO_CONTINUE James Houghton
2023-01-05 10:18 ` [PATCH 02/46] hugetlb: remove mk_huge_pte; it is unused James Houghton
2023-01-05 10:18 ` [PATCH 03/46] hugetlb: remove redundant pte_mkhuge in migration path James Houghton
2023-01-05 10:18 ` [PATCH 04/46] hugetlb: only adjust address ranges when VMAs want PMD sharing James Houghton
2023-01-05 10:18 ` [PATCH 05/46] hugetlb: add CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING James Houghton
2023-01-05 10:18 ` [PATCH 06/46] mm: add VM_HUGETLB_HGM VMA flag James Houghton
2023-01-05 10:18 ` [PATCH 07/46] hugetlb: rename __vma_shareable_flags_pmd to __vma_has_hugetlb_vma_lock James Houghton
2023-01-05 10:18 ` [PATCH 08/46] hugetlb: add HugeTLB HGM enablement helpers James Houghton
2023-01-05 10:18 ` [PATCH 09/46] mm: add MADV_SPLIT to enable HugeTLB HGM James Houghton
2023-01-05 15:05 ` kernel test robot
2023-01-05 15:29 ` David Hildenbrand
2023-01-10 0:01 ` Zach O'Keefe
2023-01-05 10:18 ` [PATCH 10/46] hugetlb: make huge_pte_lockptr take an explicit shift argument James Houghton
2023-01-05 10:18 ` [PATCH 11/46] hugetlb: add hugetlb_pte to track HugeTLB page table entries James Houghton
2023-01-05 16:06 ` kernel test robot
2023-01-05 10:18 ` [PATCH 12/46] hugetlb: add hugetlb_alloc_pmd and hugetlb_alloc_pte James Houghton
2023-01-05 10:18 ` [PATCH 13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step James Houghton
2023-01-05 16:57 ` kernel test robot
2023-01-05 18:58 ` kernel test robot
2023-01-11 21:51 ` Peter Xu
2023-01-12 13:38 ` James Houghton
2023-01-05 10:18 ` [PATCH 14/46] hugetlb: add make_huge_pte_with_shift James Houghton
2023-01-05 10:18 ` [PATCH 15/46] hugetlb: make default arch_make_huge_pte understand small mappings James Houghton
2023-01-05 10:18 ` [PATCH 16/46] hugetlbfs: do a full walk to check if vma maps a page James Houghton
2023-01-05 10:18 ` [PATCH 17/46] hugetlb: make unmapping compatible with high-granularity mappings James Houghton
2023-01-05 10:18 ` [PATCH 18/46] hugetlb: add HGM support for hugetlb_change_protection James Houghton
2023-01-05 10:18 ` [PATCH 19/46] hugetlb: add HGM support for follow_hugetlb_page James Houghton
2023-01-05 22:26 ` Peter Xu
2023-01-12 18:02 ` Peter Xu
2023-01-12 18:06 ` James Houghton
2023-01-05 10:18 ` [PATCH 20/46] hugetlb: add HGM support for hugetlb_follow_page_mask James Houghton
2023-01-05 10:18 ` [PATCH 21/46] hugetlb: use struct hugetlb_pte for walk_hugetlb_range James Houghton
2023-01-05 22:42 ` Peter Xu
2023-01-11 22:58 ` Peter Xu
2023-01-12 14:06 ` James Houghton
2023-01-12 15:29 ` Peter Xu
2023-01-12 16:45 ` James Houghton
2023-01-12 16:55 ` James Houghton
2023-01-12 20:27 ` Peter Xu
2023-01-12 21:17 ` James Houghton
2023-01-12 21:33 ` Peter Xu
2023-01-16 10:17 ` David Hildenbrand
2023-01-17 23:11 ` James Houghton
2023-01-18 9:43 ` David Hildenbrand
2023-01-18 15:35 ` Peter Xu
2023-01-18 16:39 ` James Houghton
2023-01-18 18:21 ` David Hildenbrand
2023-01-18 19:28 ` Mike Kravetz
2023-01-19 16:57 ` James Houghton
2023-01-19 17:31 ` Mike Kravetz
2023-01-19 19:42 ` James Houghton
2023-01-19 20:53 ` Peter Xu
2023-01-19 22:45 ` James Houghton
2023-01-19 22:00 ` Mike Kravetz
2023-01-19 22:23 ` Peter Xu
2023-01-19 22:35 ` James Houghton
2023-01-19 23:07 ` Peter Xu
2023-01-19 23:26 ` James Houghton
2023-01-20 17:23 ` Peter Xu
2023-01-19 23:44 ` Mike Kravetz
2023-01-23 15:19 ` Peter Xu
2023-01-23 17:49 ` Mike Kravetz
2023-01-26 16:58 ` James Houghton
2023-01-26 20:30 ` Peter Xu
2023-01-27 21:02 ` James Houghton
2023-01-30 17:29 ` Peter Xu
2023-01-30 18:38 ` James Houghton
2023-01-30 21:14 ` Peter Xu
2023-02-01 0:24 ` James Houghton
2023-02-01 1:24 ` Peter Xu
2023-02-01 15:45 ` James Houghton
2023-02-01 15:56 ` David Hildenbrand
2023-02-01 17:58 ` James Houghton
2023-02-01 18:01 ` David Hildenbrand
2023-02-01 16:22 ` Peter Xu
2023-02-01 21:32 ` James Houghton
2023-02-01 21:51 ` Peter Xu
2023-02-02 0:24 ` James Houghton
2023-02-07 16:30 ` James Houghton
2023-02-07 22:46 ` James Houghton
2023-02-07 23:13 ` Peter Xu
2023-02-08 0:26 ` James Houghton
2023-02-08 16:16 ` Peter Xu
2023-02-09 16:43 ` James Houghton
2023-02-09 19:10 ` Peter Xu
2023-02-09 19:49 ` James Houghton
2023-02-09 20:22 ` Peter Xu
2023-01-18 17:08 ` David Hildenbrand
2023-01-05 10:18 ` [PATCH 22/46] mm: rmap: provide pte_order in page_vma_mapped_walk James Houghton
2023-01-05 10:18 ` [PATCH 23/46] mm: rmap: make page_vma_mapped_walk callers use pte_order James Houghton
2023-01-05 10:18 ` [PATCH 24/46] rmap: update hugetlb lock comment for HGM James Houghton
2023-01-05 10:18 ` [PATCH 25/46] hugetlb: update page_vma_mapped to do high-granularity walks James Houghton
2023-01-05 10:18 ` [PATCH 26/46] hugetlb: add HGM support for copy_hugetlb_page_range James Houghton
2023-01-05 10:18 ` [PATCH 27/46] hugetlb: add HGM support for move_hugetlb_page_tables James Houghton
2023-01-05 10:18 ` [PATCH 28/46] hugetlb: add HGM support for hugetlb_fault and hugetlb_no_page James Houghton
2023-01-05 10:18 ` [PATCH 29/46] rmap: in try_to_{migrate,unmap}_one, check head page for page flags James Houghton
2023-01-05 10:18 ` [PATCH 30/46] hugetlb: add high-granularity migration support James Houghton
2023-01-05 10:18 ` [PATCH 31/46] hugetlb: sort hstates in hugetlb_init_hstates James Houghton
2023-01-05 10:18 ` [PATCH 32/46] hugetlb: add for_each_hgm_shift James Houghton
2023-01-05 10:18 ` [PATCH 33/46] hugetlb: userfaultfd: add support for high-granularity UFFDIO_CONTINUE James Houghton
2023-01-05 10:18 ` [PATCH 34/46] hugetlb: userfaultfd: when using MADV_SPLIT, round addresses to PAGE_SIZE James Houghton
2023-01-06 15:13 ` Peter Xu
2023-01-10 14:50 ` James Houghton [this message]
2023-01-05 10:18 ` [PATCH 35/46] hugetlb: add MADV_COLLAPSE for hugetlb James Houghton
2023-01-10 20:04 ` James Houghton
2023-01-17 21:06 ` Peter Xu
2023-01-17 21:38 ` James Houghton
2023-01-17 21:54 ` Peter Xu
2023-01-19 22:37 ` Peter Xu
2023-01-19 23:06 ` James Houghton
2023-01-05 10:18 ` [PATCH 36/46] hugetlb: remove huge_pte_lock and huge_pte_lockptr James Houghton
2023-01-05 10:18 ` [PATCH 37/46] hugetlb: replace make_huge_pte with make_huge_pte_with_shift James Houghton
2023-01-05 10:18 ` [PATCH 38/46] mm: smaps: add stats for HugeTLB mapping size James Houghton
2023-01-05 10:18 ` [PATCH 39/46] hugetlb: x86: enable high-granularity mapping James Houghton
2023-01-12 20:07 ` James Houghton
2023-01-05 10:18 ` [PATCH 40/46] docs: hugetlb: update hugetlb and userfaultfd admin-guides with HGM info James Houghton
2023-01-05 10:18 ` [PATCH 41/46] docs: proc: include information about HugeTLB HGM James Houghton
2023-01-05 10:18 ` [PATCH 42/46] selftests/vm: add HugeTLB HGM to userfaultfd selftest James Houghton
2023-01-05 10:18 ` [PATCH 43/46] selftests/kvm: add HugeTLB HGM to KVM demand paging selftest James Houghton
2023-01-05 10:18 ` [PATCH 44/46] selftests/vm: add anon and shared hugetlb to migration test James Houghton
2023-01-05 10:18 ` [PATCH 45/46] selftests/vm: add hugetlb HGM test to migration selftest James Houghton
2023-01-05 10:18 ` [PATCH 46/46] selftests/vm: add HGM UFFDIO_CONTINUE and hwpoison tests James Houghton
2023-01-05 10:47 ` [PATCH 00/46] Based on latest mm-unstable (85b44c25cd1e) David Hildenbrand
2023-01-09 19:53 ` Mike Kravetz
2023-01-10 15:47 ` David Hildenbrand
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