[to-be-updated] hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb.patch removed from -mm tree

[to-be-updated] hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb.patch removed from -mm tree

[akpm]

The patch titled
     Subject: hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb
has been removed from the -mm tree.  Its filename was
     hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb.patch

This patch was dropped because an updated version will be merged

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb

i_mmap_mutex lock was added in unmap_single_vma by 502717f4e ("hugetlb:
fix linked list corruption in unmap_hugepage_range()") but we don't use
page->lru in unmap_hugepage_range any more.  Also the lock was taken
higher up in the stack in some code path.  That would result in deadlock.

unmap_mapping_range (i_mmap_mutex)
 -> unmap_mapping_range_tree
    -> unmap_mapping_range_vma
       -> zap_page_range_single
         -> unmap_single_vma
	      -> unmap_hugepage_range (i_mmap_mutex)

For shared pagetable support for huge pages, since pagetable pages are ref
counted we don't need any lock during huge_pmd_unshare.  We do take
i_mmap_mutex in huge_pmd_share while walking the vma_prio_tree in mapping.
(39dde65c9940c97f ("shared page table for hugetlb page")).

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff -puN mm/memory.c~hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb mm/memory.c
--- a/mm/memory.c~hugetlb-avoid-taking-i_mmap_mutex-in-unmap_single_vma-for-hugetlb
+++ a/mm/memory.c
@@ -1328,11 +1328,8 @@ static void unmap_single_vma(struct mmu_
 			 * Since no pte has actually been setup, it is
 			 * safe to do nothing in this case.
 			 */
-			if (vma->vm_file) {
-				mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
+			if (vma->vm_file)
 				__unmap_hugepage_range(tlb, vma, start, end, NULL);
-				mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
-			}
 		} else
 			unmap_page_range(tlb, vma, start, end, details);
 	}
_

Patches currently in -mm which might be from aneesh.kumar@linux.vnet.ibm.com are

linux-next.patch
hugetlb-simplify-migrate_huge_page.patch
hugetlb-simplify-migrate_huge_page-fix.patch
memcg-add-hugetlb-extension.patch
memcg-add-hugetlb-extension-fix.patch
memcg-add-hugetlb-extension-fix-fix.patch
hugetlb-add-charge-uncharge-calls-for-hugetlb-alloc-free.patch
memcg-track-resource-index-in-cftype-private.patch
hugetlbfs-add-memcg-control-files-for-hugetlbfs.patch
hugetlbfs-add-memcg-control-files-for-hugetlbfs-use-scnprintf-instead-of-sprintf.patch
hugetlbfs-add-memcg-control-files-for-hugetlbfs-use-scnprintf-instead-of-sprintf-fix.patch
hugetlbfs-add-memcg-control-files-for-hugetlbfs-add-failcnt-support-for-hugetlb-extension.patch
hugetlbfs-add-a-list-for-tracking-in-use-hugetlb-pages.patch
memcg-move-hugetlb-resource-count-to-parent-cgroup-on-memcg-removal.patch
memcg-move-hugetlb-resource-count-to-parent-cgroup-on-memcg-removal-fix.patch
memcg-move-hugetlb-resource-count-to-parent-cgroup-on-memcg-removal-fix-fix.patch
hugetlb-migrate-memcg-info-from-oldpage-to-new-page-during-migration.patch
hugetlb-migrate-memcg-info-from-oldpage-to-new-page-during-migration-fix.patch
hugetlb-migrate-memcg-info-from-oldpage-to-new-page-during-migration-fix-2.patch
memcg-add-memory-controller-documentation-for-hugetlb-management.patch
memcg-fix-error-code-in-hugetlb_force_memcg_empty.patch
memcg-fix-error-code-in-hugetlb_force_memcg_empty-v2.patch
memcg-fix-error-code-in-hugetlb_force_memcg_empty-v2-checkpatch-fixes.patch
memcg-use-res_counter_uncharge_until-in-mem_cgroup_move_hugetlb_parent.patch
memcg-move-charges-to-root-cgroup-if-use_hierarchy=0-in-mem_cgroup_move_hugetlb_parent.patch