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huge pagecache: extend mremap pmd rmap lockout to files 

Whatever huge pagecache implementation we go with, file rmap locking
must be added to anon rmap locking, when mremap's move_page_tables()
finds a pmd_trans_huge pmd entry: a simple change, let's do it now.

Factor out take_rmap_locks() and drop_rmap_locks() to handle the locking
for make move_ptes() and move_page_tables(), and delete the
VM_BUG_ON_VMA which rejected vm_file and required anon_vma.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2016-05-19 17:12:57 -07:00 committed by Linus Torvalds
parent bf8616d5fa
commit 1d069b7dd5
1 changed files with 22 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
mm/mremap.c
View File

@ -70,6 +70,22 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
return pmd;
}
static void take_rmap_locks(struct vm_area_struct *vma)
{
if (vma->vm_file)
i_mmap_lock_write(vma->vm_file->f_mapping);
if (vma->anon_vma)
anon_vma_lock_write(vma->anon_vma);
}
static void drop_rmap_locks(struct vm_area_struct *vma)
{
if (vma->anon_vma)
anon_vma_unlock_write(vma->anon_vma);
if (vma->vm_file)
i_mmap_unlock_write(vma->vm_file->f_mapping);
}
static pte_t move_soft_dirty_pte(pte_t pte)
{
/*
@ -90,8 +106,6 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
struct vm_area_struct *new_vma, pmd_t *new_pmd,
unsigned long new_addr, bool need_rmap_locks)
{
struct address_space *mapping = NULL;
struct anon_vma *anon_vma = NULL;
struct mm_struct *mm = vma->vm_mm;
pte_t *old_pte, *new_pte, pte;
spinlock_t *old_ptl, *new_ptl;
@ -114,16 +128,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
* serialize access to individual ptes, but only rmap traversal
* order guarantees that we won't miss both the old and new ptes).
*/
if (need_rmap_locks) {
if (vma->vm_file) {
mapping = vma->vm_file->f_mapping;
i_mmap_lock_write(mapping);
}
if (vma->anon_vma) {
anon_vma = vma->anon_vma;
anon_vma_lock_write(anon_vma);
}
}
if (need_rmap_locks)
take_rmap_locks(vma);
/*
* We don't have to worry about the ordering of src and dst
@ -151,10 +157,8 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
spin_unlock(new_ptl);
pte_unmap(new_pte - 1);
pte_unmap_unlock(old_pte - 1, old_ptl);
if (anon_vma)
anon_vma_unlock_write(anon_vma);
if (mapping)
i_mmap_unlock_write(mapping);
if (need_rmap_locks)
drop_rmap_locks(vma);
}
#define LATENCY_LIMIT (64 * PAGE_SIZE)
@ -193,15 +197,13 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
if (pmd_trans_huge(*old_pmd)) {
if (extent == HPAGE_PMD_SIZE) {
bool moved;
VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma,
vma);
/* See comment in move_ptes() */
if (need_rmap_locks)
anon_vma_lock_write(vma->anon_vma);
take_rmap_locks(vma);
moved = move_huge_pmd(vma, old_addr, new_addr,
old_end, old_pmd, new_pmd);
if (need_rmap_locks)
anon_vma_unlock_write(vma->anon_vma);
drop_rmap_locks(vma);
if (moved) {
need_flush = true;
continue;