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path: root/drivers/staging/android/ashmem.c
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Diffstat (limited to 'drivers/staging/android/ashmem.c')
-rw-r--r--drivers/staging/android/ashmem.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 9481c0b23386..22cae548df49 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -100,6 +100,15 @@ static DEFINE_MUTEX(ashmem_mutex);
static struct kmem_cache *ashmem_area_cachep __read_mostly;
static struct kmem_cache *ashmem_range_cachep __read_mostly;
+/*
+ * A separate lockdep class for the backing shmem inodes to resolve the lockdep
+ * warning about the race between kswapd taking fs_reclaim before inode_lock
+ * and write syscall taking inode_lock and then fs_reclaim.
+ * Note that such race is impossible because ashmem does not support write
+ * syscalls operating on the backing shmem.
+ */
+static struct lock_class_key backing_shmem_inode_class;
+
static inline unsigned long range_size(struct ashmem_range *range)
{
return range->pgend - range->pgstart + 1;
@@ -406,6 +415,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
if (!asma->file) {
char *name = ASHMEM_NAME_DEF;
struct file *vmfile;
+ struct inode *inode;
if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
name = asma->name;
@@ -417,6 +427,8 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
goto out;
}
vmfile->f_mode |= FMODE_LSEEK;
+ inode = file_inode(vmfile);
+ lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
asma->file = vmfile;
/*
* override mmap operation of the vmfile so that it can't be