mm: strictly nested kmap_atomic()

Ensure kmap_atomic() usage is strictly nested
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

crypto/async_tx/async_memcpy.c

@@ -83,8 +83,8 @@ async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
 
 		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

@@ -89,9 +89,9 @@ static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
 		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

@@ -101,8 +101,8 @@ static int transfer_none(struct loop_device *lo, int cmd,
 	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;
 }
@@ -130,8 +130,8 @@ static int transfer_xor(struct loop_device *lo, int cmd,
 	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

@@ -201,8 +201,8 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
 	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
@@ -214,8 +214,8 @@ static inline void copy_highpage(struct page *to, struct page *from)
 	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

@@ -984,8 +984,8 @@ static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 		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
@@ -2273,8 +2273,8 @@ swap_two_pages_data(struct page *p1, struct page *p2, void *buf)
 	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);
 }
 
 /**