From: Andi Kleen Date: Wed, 24 Jun 2015 23:56:02 +0000 (-0700) Subject: mm, hwpoison: add comment describing when to add new cases X-Git-Tag: v5.15~15582^2~60 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=e0de78dfb4655752897d123a8cce6ecab4175dc9;p=mirror_ubuntu-kernels.git 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 Acked-by: Naoya Horiguchi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 501820c815b3..dfa9dd7f1aea 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