From: Matthew Wilcox <willy@infradead.org>
To: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, songmuchun@bytedance.com,
mike.kravetz@oracle.com, jhubbard@nvidia.com
Subject: Re: [PATCH 4/9] mm/rmap: change hugepage_add_new_anon_rmap to take in a folio
Date: Fri, 20 Jan 2023 21:17:14 +0000 [thread overview]
Message-ID: <Y8sE2l7EvBPnTCab@casper.infradead.org> (raw)
In-Reply-To: <9c276d01-379f-9bd7-0a7a-6a831b7b4571@oracle.com>
On Fri, Jan 20, 2023 at 12:45:38PM -0800, Sidhartha Kumar wrote:
> > > @@ -6176,6 +6186,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
> > > spinlock_t *ptl;
> > > int ret = -ENOMEM;
> > > struct page *page;
> > > + struct folio *folio = NULL;
> > > int writable;
> > > bool page_in_pagecache = false;
> > > @@ -6251,12 +6262,15 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
> > > *pagep = NULL;
> > > }
> > > + if (page)
> > > + folio = page_folio(page);
> > > +
> > > /*
> > > - * The memory barrier inside __SetPageUptodate makes sure that
> > > + * The memory barrier inside __folio_mark_uptodate makes sure that
> > > * preceding stores to the page contents become visible before
> > > * the set_pte_at() write.
> > > */
> > > - __SetPageUptodate(page);
> > > + __folio_mark_uptodate(folio);
> >
>
> Hi Matthew,
>
> In the snippet:
>
> page = alloc_huge_page(dst_vma, dst_addr, 0);
> if (IS_ERR(page)) {
> put_page(*pagep);
> ret = -ENOMEM;
> *pagep = NULL;
> goto out;
> }
> copy_user_huge_page(page, *pagep, dst_addr, dst_vma,
> pages_per_huge_page(h));
>
> I thought the IS_ERR() call does not handle the NULL case and is a check for
> high memory addresses, and copy_user_huge_page() path does not seem to
> handle the NULL case as well but alloc_huge_page() can possibly return NULL
> so I was unsure about how to handle the folio conversion.
I'm not sure how alloc_huge_page() can return NULL. It seems like it
returns ERR_PTR(-ENOSPC) or ERR_PTR(-ENOMEM) if it cannot allocate memory?
next prev parent reply other threads:[~2023-01-20 21:17 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-19 21:14 [PATCH 0/9] convert hugetlb fault functions to folios Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 1/9] mm/hugetlb: convert hugetlb_install_page " Sidhartha Kumar
2023-01-20 23:21 ` Mike Kravetz
2023-01-19 21:14 ` [PATCH 2/9] mm/hugetlb: convert hugetlbfs_pagecache_present() " Sidhartha Kumar
2023-01-20 5:43 ` Matthew Wilcox
2023-01-20 23:40 ` Mike Kravetz
2023-01-19 21:14 ` [PATCH 3/9] mm/hugetlb: convert putback_active_hugepage to take in a folio Sidhartha Kumar
2023-01-20 5:48 ` Matthew Wilcox
2023-01-20 23:47 ` Mike Kravetz
2023-01-19 21:14 ` [PATCH 4/9] mm/rmap: change hugepage_add_new_anon_rmap " Sidhartha Kumar
2023-01-20 6:00 ` Matthew Wilcox
2023-01-20 20:45 ` Sidhartha Kumar
2023-01-20 21:17 ` Matthew Wilcox [this message]
2023-01-20 22:05 ` Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 5/9] mm/hugetlb: convert alloc_huge_page to alloc_hugetlb_folio Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 6/9] mm/hugetlb: convert restore_reserve_on_error to take in a folio Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 7/9] mm/hugetlb: convert hugetlb_add_to_page_cache " Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 8/9] mm/hugetlb: convert hugetlb_wp() " Sidhartha Kumar
2023-01-24 15:23 ` Gerald Schaefer
2023-01-24 18:38 ` Sidhartha Kumar
2023-01-19 21:14 ` [PATCH 9/9] Documentation/mm: update hugetlbfs documentation to mention alloc_hugetlb_folio Sidhartha Kumar
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