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mm/memory.c: properly pte_offset_map_lock/unlock in vm_insert_pages() 

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.

Link: http://lkml.kernel.org/r/20200618220446.20284-1-arjunroy.kdev@gmail.com
Fixes: 8cd3984d81 ("mm/memory.c: add vm_insert_pages()")
Signed-off-by: Arjun Roy <arjunroy@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Arjun Roy 2020-06-25 20:30:01 -07:00 committed by Linus Torvalds
parent 243bce09c9
commit 7f70c2a68a
1 changed files with 11 additions and 10 deletions
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21
mm/memory.c
View File

@ -1498,7 +1498,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
}
#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_struct *mm, pmd_t *pmd,
if (!page_count(page))
return -EINVAL;
err = 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);
}
/* 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 = NULL;
spinlock_t *pte_lock = NULL;
pte_t *start_pte, *pte;
spinlock_t *pte_lock;
struct mm_struct *const mm = vma->vm_mm;
unsigned long curr_page_idx = 0;
unsigned long remaining_pages_total = *num;
@ -1536,18 +1538,17 @@ static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
ret = -ENOMEM;
if (pte_alloc(mm, pmd))
goto out;
pte_lock = pte_lockptr(mm, pmd);
while (pages_to_write_in_pmd) {
int pte_idx = 0;
const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
spin_lock(pte_lock);
for (; pte_idx < batch_size; ++pte_idx) {
int err = insert_page_in_batch_locked(mm, pmd,
start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
int err = 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 = err;
remaining_pages_total -= pte_idx;
goto out;
@ -1555,7 +1556,7 @@ static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
addr += PAGE_SIZE;
++curr_page_idx;
}
spin_unlock(pte_lock);
pte_unmap_unlock(start_pte, pte_lock);
pages_to_write_in_pmd -= batch_size;
remaining_pages_total -= batch_size;
}