From: Nadav Amit <nadav.amit@gmail.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Linux-MM <linux-mm@kvack.org>,
kernel list <linux-kernel@vger.kernel.org>,
Naoya Horiguchi <naoya.horiguchi@linux.dev>,
David Hildenbrand <david@redhat.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Mina Almasry <almasrymina@google.com>,
Peter Xu <peterx@redhat.com>, Rik van Riel <riel@surriel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Wei Chen <harperchen1110@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v8 1/2] hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing
Date: Thu, 10 Nov 2022 14:22:33 -0800 [thread overview]
Message-ID: <05FB2C99-9141-4F2A-8664-31CA5587B310@gmail.com> (raw)
In-Reply-To: <Y21xlgG6sxP6q5K9@monkey>
On Nov 10, 2022, at 1:48 PM, Mike Kravetz <mike.kravetz@oracle.com> wrote:
>>> void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
>>> unsigned long end, struct page *ref_page,
>>> zap_flags_t zap_flags)
>>> {
>>> + struct mmu_notifier_range range;
>>> struct mmu_gather tlb;
>>>
>>> + mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, vma->vm_mm,
>>> + start, end);
>>> + adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end);
>>> tlb_gather_mmu(&tlb, vma->vm_mm);
>>> +
>>> __unmap_hugepage_range(&tlb, vma, start, end, ref_page, zap_flags);
>>
>> Is there a reason for not using range.start and range.end?
>
> After calling adjust_range_if_pmd_sharing_possible, range.start - range.end
> could be much greater than the range we actually want to unmap. The range
> gets adjusted to account for pmd sharing if that is POSSIBLE. It does not
> know for sure if we will actually 'unshare a pmd'.
>
> I suppose adjust_range_if_pmd_sharing_possible could be modified to actually
> check if unmapping will result in unsharing, but it does not do that today.
Thanks for the explanation. It’s probably me, but I am still not sure that I
understand the the different between __unmap_hugepage_range() using (start,
end) and __zap_page_range_single() using (address, range.end). Perhaps it
worth a comment in the code?
But anyhow… shouldn’t unmap_hugepage_range() call
mmu_notifier_invalidate_range_start()?
next prev parent reply other threads:[~2022-11-10 22:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 1:19 [PATCH v8 0/2] hugetlb MADV_DONTNEED fix and zap_page_range cleanup Mike Kravetz
2022-11-08 1:19 ` [PATCH v8 1/2] hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing Mike Kravetz
2022-11-10 20:56 ` Peter Xu
2022-11-10 21:55 ` Mike Kravetz
2022-11-10 20:59 ` Nadav Amit
2022-11-10 21:48 ` Mike Kravetz
2022-11-10 22:07 ` Peter Xu
2022-11-10 22:22 ` Nadav Amit [this message]
2022-11-10 22:31 ` Mike Kravetz
2022-11-10 21:07 ` Peter Xu
2022-11-08 1:19 ` [PATCH v8 2/2] mm: remove zap_page_range and change callers to use zap_vma_range Mike Kravetz
2022-11-10 21:09 ` Nadav Amit
2022-11-10 21:27 ` Peter Xu
2022-11-10 22:02 ` Nadav Amit
2022-11-10 22:17 ` Mike Kravetz
2022-11-10 19:46 ` [PATCH v8 0/2] hugetlb MADV_DONTNEED fix and zap_page_range cleanup Mike Kravetz
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