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authorDavidlohr Bueso <dave@stgolabs.net>2014-12-12 16:54:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-13 12:42:45 -0800
commitc8c06efa8b552608493b7066c234cfa82c47fcea (patch)
tree7e206c669149766fb5a77a3ef85cdd4fac63be78 /mm/mmap.c
parent83cde9e8ba95d180eaefefe834958fbf7008cf39 (diff)
downloadlinux-c8c06efa8b552608493b7066c234cfa82c47fcea.tar.gz
mm: convert i_mmap_mutex to rwsem
The i_mmap_mutex is a close cousin of the anon vma lock, both protecting similar data, one for file backed pages and the other for anon memory. To this end, this lock can also be a rwsem. In addition, there are some important opportunities to share the lock when there are no tree modifications. This conversion is straightforward. For now, all users take the write lock. [sfr@canb.auug.org.au: update fremap.c] Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name> Acked-by: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
-rw-r--r--mm/mmap.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index ecd6ecf4877..0d84b2f86f3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -232,7 +232,7 @@ error:
}
/*
- * Requires inode->i_mapping->i_mmap_mutex
+ * Requires inode->i_mapping->i_mmap_rwsem
*/
static void __remove_shared_vm_struct(struct vm_area_struct *vma,
struct file *file, struct address_space *mapping)
@@ -2791,7 +2791,7 @@ void exit_mmap(struct mm_struct *mm)
/* Insert vm structure into process list sorted by address
* and into the inode's i_mmap tree. If vm_file is non-NULL
- * then i_mmap_mutex is taken here.
+ * then i_mmap_rwsem is taken here.
*/
int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
{
@@ -3086,7 +3086,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
*/
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
BUG();
- mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
+ down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
}
}
@@ -3113,7 +3113,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
* vma in this mm is backed by the same anon_vma or address_space.
*
* We can take all the locks in random order because the VM code
- * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never
+ * taking i_mmap_rwsem or anon_vma->rwsem outside the mmap_sem never
* takes more than one of them in a row. Secondly we're protected
* against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
*