[PATCH] mm: rmap with inner ptlock
rmap's page_check_address descend without page_table_lock. First just
pte_offset_map in case there's no pte present worth locking for, then take
page_table_lock for the full check, and pass ptl back to caller in the same
style as pte_offset_map_lock. __xip_unmap, page_referenced_one and
try_to_unmap_one use pte_unmap_unlock. try_to_unmap_cluster also.
page_check_address reformatted to avoid progressive indentation. No use is
made of its one error code, return NULL when it fails.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 4e74ad6..9cf687e 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -174,6 +174,7 @@
unsigned long address;
pte_t *pte;
pte_t pteval;
+ spinlock_t *ptl;
struct page *page;
spin_lock(&mapping->i_mmap_lock);
@@ -183,20 +184,15 @@
((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
page = ZERO_PAGE(address);
- /*
- * We need the page_table_lock to protect us from page faults,
- * munmap, fork, etc...
- */
- pte = page_check_address(page, mm, address);
- if (!IS_ERR(pte)) {
+ pte = page_check_address(page, mm, address, &ptl);
+ if (pte) {
/* Nuke the page table entry. */
flush_cache_page(vma, address, pte_pfn(*pte));
pteval = ptep_clear_flush(vma, address, pte);
page_remove_rmap(page);
dec_mm_counter(mm, file_rss);
BUG_ON(pte_dirty(pteval));
- pte_unmap(pte);
- spin_unlock(&mm->page_table_lock);
+ pte_unmap_unlock(pte, ptl);
page_cache_release(page);
}
}