From: Mike Kravetz <mike.kravetz@oracle.com>
To: Baolin Wang <baolin.wang@linux.alibaba.com>,
akpm@linux-foundation.org, catalin.marinas@arm.com,
will@kernel.org
Cc: tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com,
deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org,
paulus@samba.org, hca@linux.ibm.com, gor@linux.ibm.com,
agordeev@linux.ibm.com, borntraeger@linux.ibm.com,
svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org,
davem@davemloft.net, arnd@arndb.de,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration
Date: Thu, 5 May 2022 16:53:35 -0700 [thread overview]
Message-ID: <5cab0eca-9630-a7c6-4f5d-5cb45ff82c83@oracle.com> (raw)
In-Reply-To: <11b92502b3df0e0bba6a1dc71476d79cab6c79ba.1651216964.git.baolin.wang@linux.alibaba.com>
On 4/29/22 01:14, Baolin Wang wrote:
> On some architectures (like ARM64), it can support CONT-PTE/PMD size
> hugetlb, which means it can support not only PMD/PUD size hugetlb:
> 2M and 1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page
> size specified.
<snip>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 6fdd198..7cf2408 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1924,13 +1924,15 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
> break;
> }
> }
> +
> + /* Nuke the hugetlb page table entry */
> + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte);
> } else {
> flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
> + /* Nuke the page table entry. */
> + pteval = ptep_clear_flush(vma, address, pvmw.pte);
> }
>
On arm64 with CONT-PTE/PMD the returned pteval will have dirty or young set
if ANY of the PTE/PMDs had dirty or young set.
> - /* Nuke the page table entry. */
> - pteval = ptep_clear_flush(vma, address, pvmw.pte);
> -
> /* Set the dirty flag on the folio now the pte is gone. */
> if (pte_dirty(pteval))
> folio_mark_dirty(folio);
> @@ -2015,7 +2017,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
> pte_t swp_pte;
>
> if (arch_unmap_one(mm, vma, address, pteval) < 0) {
> - set_pte_at(mm, address, pvmw.pte, pteval);
> + if (folio_test_hugetlb(folio))
> + set_huge_pte_at(mm, address, pvmw.pte, pteval);
And, we will use that pteval for ALL the PTE/PMDs here. So, we would set
the dirty or young bit in ALL PTE/PMDs.
Could that cause any issues? May be more of a question for the arm64 people.
--
Mike Kravetz
next prev parent reply other threads:[~2022-05-05 23:54 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 8:14 [PATCH 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
2022-04-29 8:14 ` [PATCH 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
2022-05-05 23:15 ` Mike Kravetz
2022-05-06 3:02 ` Baolin Wang
2022-04-29 8:14 ` [PATCH 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
2022-05-05 23:53 ` Mike Kravetz [this message]
2022-05-06 3:39 ` Baolin Wang
2022-05-06 17:56 ` Mike Kravetz
2022-05-07 2:33 ` Baolin Wang
2022-05-08 9:19 ` Baolin Wang
2022-04-29 8:14 ` [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Baolin Wang
2022-04-29 20:02 ` Gerald Schaefer
2022-04-30 3:22 ` Baolin Wang
2022-05-02 14:02 ` Gerald Schaefer
2022-05-03 2:19 ` Baolin Wang
2022-05-03 10:03 ` Gerald Schaefer
2022-05-03 13:33 ` Baolin Wang
2022-05-06 19:07 ` Mike Kravetz
2022-05-09 16:41 ` Peter Xu
2022-05-10 1:28 ` Baolin Wang
2022-05-06 18:55 ` Mike Kravetz
2022-05-07 1:32 ` Baolin Wang
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