Commit d850fa72 authored by Hugh Dickins's avatar Hugh Dickins Committed by Andrew Morton
Browse files

mm/swapoff: allow pte_offset_map[_lock]() to fail 

Adjust unuse_pte() and unuse_pte_range() to allow pte_offset_map_lock()
and pte_offset_map() failure; remove pmd_none_or_trans_huge_or_clear_bad()
from unuse_pmd_range() now that pte_offset_map() does all that itself.

Link: https://lkml.kernel.org/r/c4d831-13c3-9dfd-70c2-64514ad951fd@google.com


Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 179d3e4f

mm/swapfile.c

+20 −18
Original line number Diff line number Diff line
@@ -1757,7 +1757,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, 
		hwposioned = true;



	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {

	if (unlikely(!pte || !pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {

		ret = 0;

		goto out;

	}
@@ -1810,6 +1810,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, 
	set_pte_at(vma->vm_mm, addr, pte, new_pte);

	swap_free(entry);

out:

	if (pte)

		pte_unmap_unlock(pte, ptl);

	if (page != swapcache) {

		unlock_page(page);
@@ -1822,17 +1823,22 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
			unsigned long addr, unsigned long end,

			unsigned int type)

{

	swp_entry_t entry;

	pte_t *pte;

	pte_t *pte = NULL;

	struct swap_info_struct *si;

	int ret = 0;



	si = swap_info[type];

	pte = pte_offset_map(pmd, addr);

	do {

		struct folio *folio;

		unsigned long offset;

		unsigned char swp_count;

		swp_entry_t entry;

		int ret;



		if (!pte++) {

			pte = pte_offset_map(pmd, addr);

			if (!pte)

				break;

		}



		if (!is_swap_pte(*pte))

			continue;
@@ -1843,6 +1849,8 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 


		offset = swp_offset(entry);

		pte_unmap(pte);

		pte = NULL;



		folio = swap_cache_get_folio(entry, vma, addr);

		if (!folio) {

			struct page *page;
@@ -1861,8 +1869,7 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
		if (!folio) {

			swp_count = READ_ONCE(si->swap_map[offset]);

			if (swp_count == 0 || swp_count == SWAP_MAP_BAD)

				goto try_next;



				continue;

			return -ENOMEM;

		}
@@ -1872,20 +1879,17 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
		if (ret < 0) {

			folio_unlock(folio);

			folio_put(folio);

			goto out;

			return ret;

		}



		folio_free_swap(folio);

		folio_unlock(folio);

		folio_put(folio);

try_next:

		pte = pte_offset_map(pmd, addr);

	} while (pte++, addr += PAGE_SIZE, addr != end);

	pte_unmap(pte - 1);

	} while (addr += PAGE_SIZE, addr != end);



	ret = 0;

out:

	return ret;

	if (pte)

		pte_unmap(pte);

	return 0;

}



static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
@@ -1900,8 +1904,6 @@ static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, 
	do {

		cond_resched();

		next = pmd_addr_end(addr, end);

		if (pmd_none_or_trans_huge_or_clear_bad(pmd))

			continue;

		ret = unuse_pte_range(vma, pmd, addr, next, type);

		if (ret)

			return ret;