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authorAndi Kleen <ak@linux.intel.com>2015-06-24 16:56:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-24 17:49:41 -0700
commite0de78dfb4655752897d123a8cce6ecab4175dc9 (patch)
tree47a221a7054d0ff08895bb8aad55ff7940d2efe9 /mm/memory-failure.c
parent1ed58b6051b67e5cfe9e465fb60bf7d5f55e0a64 (diff)
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mm, hwpoison: add comment describing when to add new cases
Here's another comment fix for hwpoison. It describes the "guiding principle" on when to add new memory error recovery code. Signed-off-by: Andi Kleen <ak@linux.intel.com> Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory-failure.c')
-rw-r--r--mm/memory-failure.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 501820c..dfa9dd7 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -20,6 +20,14 @@
* 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.
+ *
+ * It can be very tempting to add handling for obscure cases here.
+ * In general any code for handling new cases should only be added iff:
+ * - You know how to test it.
+ * - You have a test that can be added to mce-test
+ * https://git.kernel.org/cgit/utils/cpu/mce/mce-test.git/
+ * - The case actually shows up as a frequent (top 10) page state in
+ * tools/vm/page-types when running a real workload.
*
* There are several operations here with exponential complexity because
* of unsuitable VM data structures. For example the operation to map back
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