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authorAndi Kleen <ak@linux.intel.com>2010-09-27 23:09:51 +0200
committerAndi Kleen <ak@linux.intel.com>2010-10-08 09:33:00 +0200
commit1c80b990a3411733890eff10817e388d5e25e2dd (patch)
treece5db3902697e04c78ef3a486a6d16a331a89d6c /mm/memory-failure.c
parent6b0cd00bc396daf5c2dcf17a8d82055335341f46 (diff)
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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>
Diffstat (limited to 'mm/memory-failure.c')
-rw-r--r--mm/memory-failure.c31
1 files changed, 18 insertions, 13 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 757f6b0accf..eebb9d8efae 100644
--- a/mm/memory-failure.c
+++ b/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 @@ static int hwpoison_filter_dev(struct page *p)
return 0;
/*
- * page_mapping() does not accept slab page
+ * page_mapping() does not accept slab pages.
*/
if (PageSlab(p))
return -EINVAL;