From: Oleg Nesterov <oleg@redhat.com>
To: Song Liu <songliubraving@fb.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, matthew.wilcox@oracle.com,
kirill.shutemov@linux.intel.com, kernel-team@fb.com,
william.kucharski@oracle.com, srikar@linux.vnet.ibm.com
Subject: Re: [PATCH v12 5/6] khugepaged: enable collapse pmd for pte-mapped THP
Date: Thu, 8 Aug 2019 18:33:03 +0200 [thread overview]
Message-ID: <20190808163303.GB7934@redhat.com> (raw)
In-Reply-To: <20190807233729.3899352-6-songliubraving@fb.com>
On 08/07, Song Liu wrote:
>
> +void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
> +{
> + unsigned long haddr = addr & HPAGE_PMD_MASK;
> + struct vm_area_struct *vma = find_vma(mm, haddr);
> + struct page *hpage = NULL;
> + pmd_t *pmd, _pmd;
> + spinlock_t *ptl;
> + int count = 0;
> + int i;
> +
> + if (!vma || !vma->vm_file ||
> + vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE)
> + return;
> +
> + /*
> + * This vm_flags may not have VM_HUGEPAGE if the page was not
> + * collapsed by this mm. But we can still collapse if the page is
> + * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()
> + * will not fail the vma for missing VM_HUGEPAGE
> + */
> + if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE))
> + return;
> +
> + pmd = mm_find_pmd(mm, haddr);
OK, I do not see anything really wrong...
a couple of questions below.
> + for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) {
> + pte_t *pte = pte_offset_map(pmd, addr);
> + struct page *page;
> +
> + if (pte_none(*pte))
> + continue;
> +
> + page = vm_normal_page(vma, addr, *pte);
> +
> + if (!page || !PageCompound(page))
> + return;
> +
> + if (!hpage) {
> + hpage = compound_head(page);
OK,
> + if (hpage->mapping != vma->vm_file->f_mapping)
> + return;
is it really possible? May be WARN_ON(hpage->mapping != vm_file->f_mapping)
makes more sense ?
> + if (hpage + i != page)
> + return;
ditto.
Oleg.
next prev parent reply other threads:[~2019-08-08 16:33 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 23:37 [PATCH v12 0/6] THP aware uprobe Song Liu
2019-08-07 23:37 ` [PATCH v12 1/6] mm: move memcmp_pages() and pages_identical() Song Liu
2019-08-07 23:37 ` [PATCH v12 2/6] uprobe: use original page when all uprobes are removed Song Liu
2019-08-07 23:37 ` [PATCH v12 3/6] mm, thp: introduce FOLL_SPLIT_PMD Song Liu
2019-08-08 16:37 ` Oleg Nesterov
2019-08-08 17:16 ` Song Liu
2019-08-09 16:35 ` Oleg Nesterov
2019-08-09 16:50 ` Song Liu
2019-08-07 23:37 ` [PATCH v12 4/6] uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT Song Liu
2019-08-07 23:37 ` [PATCH v12 5/6] khugepaged: enable collapse pmd for pte-mapped THP Song Liu
2019-08-08 16:33 ` Oleg Nesterov [this message]
2019-08-08 17:05 ` Song Liu
2019-08-09 15:24 ` Oleg Nesterov
2019-08-09 16:30 ` Song Liu
2019-08-09 18:01 ` Song Liu
2019-08-12 12:11 ` Kirill A. Shutemov
2019-08-12 13:22 ` Oleg Nesterov
2019-08-12 14:40 ` Kirill A. Shutemov
2019-08-12 21:04 ` Song Liu
2019-08-13 14:44 ` Song Liu
2019-08-15 10:16 ` Oleg Nesterov
2019-08-15 16:27 ` Song Liu
2019-08-13 13:30 ` Oleg Nesterov
2019-08-13 14:05 ` Oleg Nesterov
2019-08-13 15:05 ` Kirill A. Shutemov
2019-08-13 16:24 ` Oleg Nesterov
2019-08-16 14:54 ` Kirill A. Shutemov
2019-08-12 13:06 ` Oleg Nesterov
2019-08-12 14:36 ` Song Liu
2019-08-07 23:37 ` [PATCH v12 6/6] uprobe: collapse THP pmd after removing all uprobes Song Liu
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