On Mon, Oct 21, 2019 at 11:40:39AM +0200, David Hildenbrand wrote: > I explored somewhere already why this code was added: > > > commit 31d3d3484f9bd263925ecaa341500ac2df3a5d9b > Author: Wu Fengguang <fengguang.wu@xxxxxxxxx> > Date: Wed Dec 16 12:19:59 2009 +0100 > > HWPOISON: limit hwpoison injector to known page types > > __memory_failure()'s workflow is > > set PG_hwpoison > //... > unset PG_hwpoison if didn't pass hwpoison filter > > That could kill unrelated process if it happens to page fault on the > page with the (temporary) PG_hwpoison. The race should be big enough to > appear in stress tests. > > Fix it by grabbing the page and checking filter at inject time. This > also avoids the very noisy "Injecting memory failure..." messages. > > - we don't touch madvise() based injection, because the filters are > generally not necessary for it. > - if we want to apply the filters to h/w aided injection, we'd better to > rearrange the logic in __memory_failure() instead of this patch. > > AK: fix documentation, use drain all, cleanups > > > You should justify why it is okay to do rip that code out now. > It's not just duplicate checks. > > Was the documented race fixed? > Will we fix the race within memory_failure() later? > Don't we care? > > Also, you should add that this fixes the access of uninitialized memmaps > now and makes the interface work correctly with devmem. Thanks for bringuing this up David. I guess I was carried away. Since I have to do another re-spin to re-work a couple of things, I will work on this as well. -- Oscar Salvador SUSE L3
