Commit 878b0c45 authored by Peter Xu's avatar Peter Xu Committed by Andrew Morton
Browse files

mm/gup: handle hugetlb for no_page_table() 

no_page_table() is not yet used for hugetlb code paths.  Make it prepared.

The major difference here is hugetlb will return -EFAULT as long as page
cache does not exist, even if VM_SHARED.  See hugetlb_follow_page_mask().

Pass "address" into no_page_table() too, as hugetlb will need it.

Link: https://lkml.kernel.org/r/20240327152332.950956-9-peterx@redhat.com


Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@infradead.org>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Tested-by: default avatarRyan Roberts <ryan.roberts@arm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Jones <andrew.jones@linux.dev>
Cc: Aneesh Kumar K.V (IBM) <aneesh.kumar@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f3c94c62

mm/gup.c

+26 −18
Original line number Diff line number Diff line
@@ -501,19 +501,27 @@ static inline void mm_set_has_pinned_flag(unsigned long *mm_flags) 


#ifdef CONFIG_MMU

static struct page *no_page_table(struct vm_area_struct *vma,

		unsigned int flags)

				  unsigned int flags, unsigned long address)

{

	if (!(flags & FOLL_DUMP))

		return NULL;



	/*

	 * When core dumping an enormous anonymous area that nobody

	 * has touched so far, we don't want to allocate unnecessary pages or

	 * When core dumping, we don't want to allocate unnecessary pages or

	 * page tables.  Return error instead of NULL to skip handle_mm_fault,

	 * then get_dump_page() will return NULL to leave a hole in the dump.

	 * But we can only make this optimization where a hole would surely

	 * be zero-filled if handle_mm_fault() actually did handle it.

	 */

	if ((flags & FOLL_DUMP) &&

			(vma_is_anonymous(vma) || !vma->vm_ops->fault))

	if (is_vm_hugetlb_page(vma)) {

		struct hstate *h = hstate_vma(vma);



		if (!hugetlbfs_pagecache_present(h, vma, address))

			return ERR_PTR(-EFAULT);

	} else if ((vma_is_anonymous(vma) || !vma->vm_ops->fault)) {

		return ERR_PTR(-EFAULT);

	}



	return NULL;

}
@@ -593,7 +601,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, 


	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);

	if (!ptep)

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	pte = ptep_get(ptep);

	if (!pte_present(pte))

		goto no_page;
@@ -685,7 +693,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, 
	pte_unmap_unlock(ptep, ptl);

	if (!pte_none(pte))

		return NULL;

	return no_page_table(vma, flags);

	return no_page_table(vma, flags, address);

}



static struct page *follow_pmd_mask(struct vm_area_struct *vma,
@@ -701,27 +709,27 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, 
	pmd = pmd_offset(pudp, address);

	pmdval = pmdp_get_lockless(pmd);

	if (pmd_none(pmdval))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	if (!pmd_present(pmdval))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	if (pmd_devmap(pmdval)) {

		ptl = pmd_lock(mm, pmd);

		page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);

		spin_unlock(ptl);

		if (page)

			return page;

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	}

	if (likely(!pmd_trans_huge(pmdval)))

		return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);



	if (pmd_protnone(pmdval) && !gup_can_follow_protnone(vma, flags))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);



	ptl = pmd_lock(mm, pmd);

	if (unlikely(!pmd_present(*pmd))) {

		spin_unlock(ptl);

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	}

	if (unlikely(!pmd_trans_huge(*pmd))) {

		spin_unlock(ptl);
@@ -752,17 +760,17 @@ static struct page *follow_pud_mask(struct vm_area_struct *vma, 


	pud = pud_offset(p4dp, address);

	if (pud_none(*pud))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	if (pud_devmap(*pud)) {

		ptl = pud_lock(mm, pud);

		page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap);

		spin_unlock(ptl);

		if (page)

			return page;

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	}

	if (unlikely(pud_bad(*pud)))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);



	return follow_pmd_mask(vma, address, pud, flags, ctx);

}
@@ -777,10 +785,10 @@ static struct page *follow_p4d_mask(struct vm_area_struct *vma, 
	p4dp = p4d_offset(pgdp, address);

	p4d = READ_ONCE(*p4dp);

	if (!p4d_present(p4d))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);

	BUILD_BUG_ON(p4d_leaf(p4d));

	if (unlikely(p4d_bad(p4d)))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);



	return follow_pud_mask(vma, address, p4dp, flags, ctx);

}
@@ -830,7 +838,7 @@ static struct page *follow_page_mask(struct vm_area_struct *vma, 
	pgd = pgd_offset(mm, address);



	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))

		return no_page_table(vma, flags);

		return no_page_table(vma, flags, address);



	return follow_p4d_mask(vma, address, pgd, flags, ctx);

}