mm: strictly nested kmap_atomic()

Ensure kmap_atomic() usage is strictly nested

Signed-off-by: Peter Zijlstra <[e-mail]>
Reviewed-by: Rik van Riel <[e-mail]>
Acked-by: Chris Metcalf <[e-mail]>
Cc: David Howells <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: David Miller <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

crypto/async_tx/async_memcpy.c

···
 
 		memcpy(dest_buf, src_buf, len);
 
-		kunmap_atomic(dest_buf, KM_USER0);
 		kunmap_atomic(src_buf, KM_USER1);
+		kunmap_atomic(dest_buf, KM_USER0);
 
 		async_tx_sync_epilog(submit);
 	}

crypto/blkcipher.c

···
 		memcpy(walk->dst.virt.addr, walk->page, n);
 		blkcipher_unmap_dst(walk);
 	} else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
-		blkcipher_unmap_src(walk);
 		if (walk->flags & BLKCIPHER_WALK_DIFF)
 			blkcipher_unmap_dst(walk);
+		blkcipher_unmap_src(walk);
 	}
 
 	scatterwalk_advance(&walk->in, n);

drivers/block/loop.c

···
 	else
 		memcpy(raw_buf, loop_buf, size);
 
-	kunmap_atomic(raw_buf, KM_USER0);
 	kunmap_atomic(loop_buf, KM_USER1);
+	kunmap_atomic(raw_buf, KM_USER0);
 	cond_resched();
 	return 0;
 }
···
 	for (i = 0; i < size; i++)
 		*out++ = *in++ ^ key[(i & 511) % keysize];
 
-	kunmap_atomic(raw_buf, KM_USER0);
 	kunmap_atomic(loop_buf, KM_USER1);
+	kunmap_atomic(raw_buf, KM_USER0);
 	cond_resched();
 	return 0;
 }

include/linux/highmem.h

···
 	vfrom = kmap_atomic(from, KM_USER0);
 	vto = kmap_atomic(to, KM_USER1);
 	copy_user_page(vto, vfrom, vaddr, to);
-	kunmap_atomic(vfrom, KM_USER0);
 	kunmap_atomic(vto, KM_USER1);
+	kunmap_atomic(vfrom, KM_USER0);
 }
 
 #endif
···
 	vfrom = kmap_atomic(from, KM_USER0);
 	vto = kmap_atomic(to, KM_USER1);
 	copy_page(vto, vfrom);
-	kunmap_atomic(vfrom, KM_USER0);
 	kunmap_atomic(vto, KM_USER1);
+	kunmap_atomic(vfrom, KM_USER0);
 }
 
 #endif /* _LINUX_HIGHMEM_H */

kernel/power/snapshot.c

···
 		src = kmap_atomic(s_page, KM_USER0);
 		dst = kmap_atomic(d_page, KM_USER1);
 		do_copy_page(dst, src);
-		kunmap_atomic(src, KM_USER0);
 		kunmap_atomic(dst, KM_USER1);
+		kunmap_atomic(src, KM_USER0);
 	} else {
 		if (PageHighMem(d_page)) {
 			/* Page pointed to by src may contain some kernel
···
 	memcpy(buf, kaddr1, PAGE_SIZE);
 	memcpy(kaddr1, kaddr2, PAGE_SIZE);
 	memcpy(kaddr2, buf, PAGE_SIZE);
-	kunmap_atomic(kaddr1, KM_USER0);
 	kunmap_atomic(kaddr2, KM_USER1);
+	kunmap_atomic(kaddr1, KM_USER0);
 }
 
 /**