On Thu 03-01-19 17:22:29, Qian Cai wrote: > On 1/3/19 3:22 PM, Michal Hocko wrote: > > On Thu 03-01-19 14:53:47, Qian Cai wrote: > >> On 1/3/19 2:07 PM, Michal Hocko wrote> So can we make the revert with an > >> explanation that the patch was wrong? > >>> If we want to make hacks to catch more objects to be tracked then it > >>> would be great to have some numbers in hands. > >> > >> Well, those numbers are subject to change depends on future start_kernel() > >> order. Right now, there are many functions could be caught earlier by page owner. > >> > >> kmemleak_init(); > > [...] > >> sched_init_smp(); > > > > The kernel source dump will not tell us much of course. A ball park > > number whether we are talking about dozen, hundreds or thousands of > > allocations would tell us something at least, doesn't it. > > > > Handwaving that it might help us some is not particurarly useful. We are > > already losing some allocations already. Does it matter? Well, that > > depends, sometimes we do want to catch an owner of particular page and > > it is sad to find nothing. But how many times have you or somebody else > > encountered that in practice. That is exactly a useful information to > > judge an ugly ifdefery in the code. See my point? > > Here is the number without DEFERRED_STRUCT_PAGE_INIT. > > == page_ext_init() after page_alloc_init_late() == > Node 0, zone DMA: page owner found early allocated 0 pages > Node 0, zone DMA32: page owner found early allocated 7009 pages > Node 0, zone Normal: page owner found early allocated 85827 pages > Node 4, zone Normal: page owner found early allocated 75063 pages > > == page_ext_init() before kmemleak_init() == > Node 0, zone DMA: page owner found early allocated 0 pages > Node 0, zone DMA32: page owner found early allocated 6654 pages > Node 0, zone Normal: page owner found early allocated 41907 pages > Node 4, zone Normal: page owner found early allocated 41356 pages > > So, it told us that it will miss tens of thousands of early page allocation call > sites. This is an answer for the first part of the question (how much). The second is _do_we_care_? -- Michal Hocko SUSE Labs
