[PATCH] mm: unmap_vmas with inner ptlock
Remove the page_table_lock from around the calls to unmap_vmas, and replace
the pte_offset_map in zap_pte_range by pte_offset_map_lock: all callers are
now safe to descend without page_table_lock.
Don't attempt fancy locking for hugepages, just take page_table_lock in
unmap_hugepage_range. Which makes zap_hugepage_range, and the hugetlb test in
zap_page_range, redundant: unmap_vmas calls unmap_hugepage_range anyway. Nor
does unmap_vmas have much use for its mm arg now.
The tlb_start_vma and tlb_end_vma in unmap_page_range are now called without
page_table_lock: if they're implemented at all, they typically come down to
flush_cache_range (usually done outside page_table_lock) and flush_tlb_range
(which we already audited for the mprotect case).
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/mmap.c b/mm/mmap.c
index fa35323..5ecc2cf 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1673,9 +1673,7 @@
lru_add_drain();
tlb = tlb_gather_mmu(mm, 0);
update_hiwater_rss(mm);
- spin_lock(&mm->page_table_lock);
- unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted, NULL);
- spin_unlock(&mm->page_table_lock);
+ unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
next? next->vm_start: 0);
@@ -1958,9 +1956,7 @@
tlb = tlb_gather_mmu(mm, 1);
/* Don't update_hiwater_rss(mm) here, do_exit already did */
/* Use -1 here to ensure all VMAs in the mm are unmapped */
- spin_lock(&mm->page_table_lock);
- end = unmap_vmas(&tlb, mm, vma, 0, -1, &nr_accounted, NULL);
- spin_unlock(&mm->page_table_lock);
+ end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
vm_unacct_memory(nr_accounted);
free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
tlb_finish_mmu(tlb, 0, end);