Messages in this thread | | | Date | Thu, 18 Aug 2022 09:36:09 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] page_ext: move up page_ext_init() to catch early page allocation if DEFERRED_STRUCT_PAGE_INIT is n |
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On Mon 15-08-22 20:09:54, lizhe.67@bytedance.com wrote: > From: Li Zhe <lizhe.67@bytedance.com> > > In 'commit 2f1ee0913ce5 ("Revert "mm: use early_pfn_to_nid in page_ext_init"")', > we call page_ext_init() after page_alloc_init_late() to avoid some panic > problem. It seems that we cannot track early page allocations in current > kernel even if page structure has been initialized early. > > This patch move up page_ext_init() to catch early page allocations when > DEFERRED_STRUCT_PAGE_INIT is n. After this patch, we only need to turn > DEFERRED_STRUCT_PAGE_INIT to n then we are able to analyze the early page > allocations. This is useful especially when we find that the free memory > value is not the same right after different kernel booting.
is this actually useful in practice? I mean who is going to disable DEFERRED_STRUCT_PAGE_INIT and recompile the kernel for debugging early allocations?
I do see how debugging those early allocations might be useful but that would require a boot time option to be practical IMHO. Would it make sense to add a early_page_ext parameter which would essentially disable the deferred ipage initialization. That should be quite trivial to achieve (just hook into defer_init AFAICS). -- Michal Hocko SUSE Labs
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