On Mon, Mar 08, 2021 at 07:58:11AM -0800, Minchan Kim wrote: > On Mon, Mar 08, 2021 at 04:42:43PM +0100, Michal Hocko wrote: > > On Mon 08-03-21 15:13:35, David Hildenbrand wrote: > > > On 08.03.21 15:11, Michal Hocko wrote: > > > > On Mon 08-03-21 14:22:12, David Hildenbrand wrote: > > > > > On 08.03.21 13:49, Michal Hocko wrote: > > > > [...] > > > > > > Earlier in the discussion I have suggested dynamic debugging facility. > > > > > > Documentation/admin-guide/dynamic-debug-howto.rst. Have you tried to > > > > > > look into that direction? > > > > > > > > > > Did you see the previous mail this is based on: > > > > > > > > > > https://lkml.kernel.org/r/YEEUq8ZRn4WyYWVx@xxxxxxxxxx > > > > > > > > > > I agree that "nofail" is misleading. Rather something like > > > > > "dump_on_failure", just a better name :) > > > > > > > > Yeah, I have read through the email thread. I just do not get why we > > > > cannot make it pr_debug() and add -DDYNAMIC_DEBUG_MODULE for > > > > page_alloc.c (I haven't checked whether that is possible for built in > > > > compile units, maybe it is not but from a quick seems it should). > > > > > > > > I really do not like this to be a part of the API. alloc_contig_range is > > > > > > Which API? > > > > Any level of the alloc_contig_range api because I strongly suspect that > > once there is something on the lower levels there will be a push to have > > it in the directly consumed api as well. Besides that I think this is > > just a wrong way to approach the problem. > > > > > It does not affect alloc_contig_range() itself, it's used > > > internally only. Sure, we could simply pr_debug() for each and every > > > migration failure. As long as it's default-disabled, sure. > > > > > > I do agree that we should look into properly including this into the dynamic > > > debugging ifrastructure. > > > > Yeah, unless we learn this is not feasible for some reason, which I do > > not see right now, then let's just make it pr_debug with the runtime > > control. > > What do you see the problem? It's the dynamic debugging facility > to enable only when admin want to use it. Otherwise, it's nop > unless is't not enabled. Furthermore, it doesn't need to invent > custom dump_page implementation(including dump_page_owner) by > chaning pr_debug. > Could you clarify your requirement? > > https://lore.kernel.org/linux-mm/YEEUq8ZRn4WyYWVx@xxxxxxxxxx/ > > Since David agreed to drop nofail option in the API, I will > keep the URL patch. I posted formal patch with Ccing dynamic debug maintainer. https://lore.kernel.org/linux-mm/20210308202047.1903802-1-minchan@xxxxxxxxxx/ Let's discuss stuff related to dynamic debug there.
