HWPOISON: Improve comments in memory-failure.c

Clean up and improve the overview comment in memory-failure.c Tidy some grammar issues in other comments. Signed-off-by: Andi Kleen <ak@linux.intel.com>

HWPOISON: Improve comments in memory-failure.c
Clean up and improve the overview comment in memory-failure.c Tidy some grammar issues in other comments. Signed-off-by: Andi Kleen <ak@linux.intel.com>
Andi Kleen
1 parent 6b0cd00bc3
Showing 1 changed file with 18 additions and 13 deletions Side-by-side Diff
mm/memory-failure.c
@@ -7,21 +7,26 @@
  * Free Software Foundation.
  *
  * High level machine check handler. Handles pages reported by the
- * hardware as being corrupted usually due to a 2bit ECC memory or cache
+ * hardware as being corrupted usually due to a multi-bit ECC memory or cache
  * failure.
+ * 
+ * In addition there is a "soft offline" entry point that allows stop using
+ * not-yet-corrupted-by-suspicious pages without killing anything.
  *
  * Handles page cache pages in various states.	The tricky part
- * here is that we can access any page asynchronous to other VM
- * users, because memory failures could happen anytime and anywhere,
- * possibly violating some of their assumptions. This is why this code
- * has to be extremely careful. Generally it tries to use normal locking
- * rules, as in get the standard locks, even if that means the
- * error handling takes potentially a long time.
- *
- * The operation to map back from RMAP chains to processes has to walk
- * the complete process list and has non linear complexity with the number
- * mappings. In short it can be quite slow. But since memory corruptions
- * are rare we hope to get away with this.
+ * here is that we can access any page asynchronously in respect to 
+ * other VM users, because memory failures could happen anytime and 
+ * anywhere. This could violate some of their assumptions. This is why 
+ * this code has to be extremely careful. Generally it tries to use 
+ * normal locking rules, as in get the standard locks, even if that means 
+ * the error handling takes potentially a long time.
+ * 
+ * There are several operations here with exponential complexity because
+ * of unsuitable VM data structures. For example the operation to map back 
+ * from RMAP chains to processes has to walk the complete process list and 
+ * has non linear complexity with the number. But since memory corruptions
+ * are rare we hope to get away with this. This avoids impacting the core 
+ * VM.
  */
  
 /*
@@ -78,7 +83,7 @@
 		return 0;
  
 	/*
-	 * page_mapping() does not accept slab page
+	 * page_mapping() does not accept slab pages.
 	 */
 	if (PageSlab(p))
 		return -EINVAL;
...	...	@@ -7,21 +7,26 @@
7	7	* Free Software Foundation.
8	8	*
9	9	* High level machine check handler. Handles pages reported by the
10		- * hardware as being corrupted usually due to a 2bit ECC memory or cache
	10	+ * hardware as being corrupted usually due to a multi-bit ECC memory or cache
11	11	* failure.
	12	+ *
	13	+ * In addition there is a "soft offline" entry point that allows stop using
	14	+ * not-yet-corrupted-by-suspicious pages without killing anything.
12	15	*
13	16	* Handles page cache pages in various states. The tricky part
14		- * here is that we can access any page asynchronous to other VM
15		- * users, because memory failures could happen anytime and anywhere,
16		- * possibly violating some of their assumptions. This is why this code
17		- * has to be extremely careful. Generally it tries to use normal locking
18		- * rules, as in get the standard locks, even if that means the
19		- * error handling takes potentially a long time.
20		- *
21		- * The operation to map back from RMAP chains to processes has to walk
22		- * the complete process list and has non linear complexity with the number
23		- * mappings. In short it can be quite slow. But since memory corruptions
24		- * are rare we hope to get away with this.
	17	+ * here is that we can access any page asynchronously in respect to
	18	+ * other VM users, because memory failures could happen anytime and
	19	+ * anywhere. This could violate some of their assumptions. This is why
	20	+ * this code has to be extremely careful. Generally it tries to use
	21	+ * normal locking rules, as in get the standard locks, even if that means
	22	+ * the error handling takes potentially a long time.
	23	+ *
	24	+ * There are several operations here with exponential complexity because
	25	+ * of unsuitable VM data structures. For example the operation to map back
	26	+ * from RMAP chains to processes has to walk the complete process list and
	27	+ * has non linear complexity with the number. But since memory corruptions
	28	+ * are rare we hope to get away with this. This avoids impacting the core
	29	+ * VM.
25	30	*/
26	31
27	32	/*
...	...	@@ -78,7 +83,7 @@
78	83	return 0;
79	84
80	85	/*
81		- * page_mapping() does not accept slab page
	86	+ * page_mapping() does not accept slab pages.
82	87	*/
83	88	if (PageSlab(p))
84	89	return -EINVAL;