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Date: Thu, 18 Jun 2020 15:04:46 -0700 Message-Id: <20200618220446.20284-1-arjunroy.kdev@gmail.com> X-Mailer: git-send-email 2.27.0.111.gc72c7da667-goog MIME-Version: 1.0 X-Rspamd-Queue-Id: D4B3A1819B12A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Arjun Roy Calls to pte_offset_map() in vm_insert_pages() are erroneously not matched with a call to pte_unmap(). This would cause problems on architectures where that is not a no-op. This patch does away with the non-traditional locking in the existing code, and instead uses pte_offset_map_lock/unlock() as usual, incrementing PTE as necessary. The PTE pointer is kept within bounds since we clamp it with PTRS_PER_PTE. Fixes: 8cd3984d81d5 ("mm/memory.c: add vm_insert_pages()") Signed-off-by: Arjun Roy Acked-by: David Rientjes --- mm/memory.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index fd5350cce71a..9f44a7af8dbc 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1498,7 +1498,7 @@ static int insert_page(struct vm_area_struct *vma, = unsigned long addr, } =20 #ifdef pte_index -static int insert_page_in_batch_locked(struct mm_struct *mm, pmd_t *pmd, +static int insert_page_in_batch_locked(struct mm_struct *mm, pte_t *pte, unsigned long addr, struct page *page, pgprot_t prot) { int err; @@ -1506,8 +1506,9 @@ static int insert_page_in_batch_locked(struct mm_st= ruct *mm, pmd_t *pmd, if (!page_count(page)) return -EINVAL; err =3D validate_page_before_insert(page); - return err ? err : insert_page_into_pte_locked( - mm, pte_offset_map(pmd, addr), addr, page, prot); + if (err) + return err; + return insert_page_into_pte_locked(mm, pte, addr, page, prot); } =20 /* insert_pages() amortizes the cost of spinlock operations @@ -1517,7 +1518,8 @@ static int insert_pages(struct vm_area_struct *vma,= unsigned long addr, struct page **pages, unsigned long *num, pgprot_t prot) { pmd_t *pmd =3D NULL; - spinlock_t *pte_lock =3D NULL; + pte_t *start_pte, *pte; + spinlock_t *pte_lock; struct mm_struct *const mm =3D vma->vm_mm; unsigned long curr_page_idx =3D 0; unsigned long remaining_pages_total =3D *num; @@ -1536,18 +1538,17 @@ static int insert_pages(struct vm_area_struct *vm= a, unsigned long addr, ret =3D -ENOMEM; if (pte_alloc(mm, pmd)) goto out; - pte_lock =3D pte_lockptr(mm, pmd); =20 while (pages_to_write_in_pmd) { int pte_idx =3D 0; const int batch_size =3D min_t(int, pages_to_write_in_pmd, 8); =20 - spin_lock(pte_lock); - for (; pte_idx < batch_size; ++pte_idx) { - int err =3D insert_page_in_batch_locked(mm, pmd, + start_pte =3D pte_offset_map_lock(mm, pmd, addr, &pte_lock); + for (pte =3D start_pte; pte_idx < batch_size; ++pte, ++pte_idx) { + int err =3D insert_page_in_batch_locked(mm, pte, addr, pages[curr_page_idx], prot); if (unlikely(err)) { - spin_unlock(pte_lock); + pte_unmap_unlock(start_pte, pte_lock); ret =3D err; remaining_pages_total -=3D pte_idx; goto out; @@ -1555,7 +1556,7 @@ static int insert_pages(struct vm_area_struct *vma,= unsigned long addr, addr +=3D PAGE_SIZE; ++curr_page_idx; } - spin_unlock(pte_lock); + pte_unmap_unlock(start_pte, pte_lock); pages_to_write_in_pmd -=3D batch_size; remaining_pages_total -=3D batch_size; } --=20 2.27.0.111.gc72c7da667-goog